Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

264 files changed, 17414 insertions, 0 deletions

diff --git a/l10n-cy/mail/all-l10n.js b/l10n-cy/mail/all-l10n.js
new file mode 100644
index 0000000000..6e0520e894
--- /dev/null
+++ b/l10n-cy/mail/all-l10n.js
@@ -0,0 +1,8 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#filter substitution
+
+pref("general.useragent.locale", "@AB_CD@");
+pref("spellchecker.dictionary", "@AB_CD@");
diff --git a/l10n-cy/mail/branding/thunderbird/brand.dtd b/l10n-cy/mail/branding/thunderbird/brand.dtd
new file mode 100644
index 0000000000..a809c8a566
--- /dev/null
+++ b/l10n-cy/mail/branding/thunderbird/brand.dtd
@@ -0,0 +1,13 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!ENTITY  brandShortName        "Thunderbird">
+<!ENTITY  brandShorterName      "Thunderbird">
+<!ENTITY  brandFullName         "Mozilla Thunderbird">
+<!-- LOCALIZATION NOTE (brandProductName):
+   This brand name can be used in messages where the product name needs to
+   remain unchanged across different versions (Daily, Beta, etc.). -->
+<!ENTITY  brandProductName      "Thunderbird">
+<!ENTITY  vendorShortName       "Mozilla">
+<!ENTITY  trademarkInfo.part1   "Mae Mozilla Thunderbird a logos Thunderbird yn
+                                  nodau masnachu'r Mozilla Foundation.">
diff --git a/l10n-cy/mail/branding/thunderbird/brand.ftl b/l10n-cy/mail/branding/thunderbird/brand.ftl
new file mode 100644
index 0000000000..2026ae846e
--- /dev/null
+++ b/l10n-cy/mail/branding/thunderbird/brand.ftl
@@ -0,0 +1,22 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Thunderbird Brand
+##
+## Thunderbird must be treated as a brand, and kept in English.
+## It cannot be:
+## - Transliterated.
+## - Translated.
+##
+## Reference: https://www.mozilla.org/styleguide/communications/translation/
+
+-brand-shorter-name = Thunderbird
+-brand-short-name = Thunderbird
+-brand-full-name = Mozilla Thunderbird
+# This brand name can be used in messages where the product name needs to
+# remain unchanged across different versions (Daily, Beta, etc.).
+-brand-product-name = Thunderbird
+-vendor-short-name = Mozilla
+trademarkInfo = Nodau masnachu'r Mozilla Foundation yw Thunderbird a logos Thunderbird.
diff --git a/l10n-cy/mail/branding/thunderbird/brand.properties b/l10n-cy/mail/branding/thunderbird/brand.properties
new file mode 100644
index 0000000000..9dd5011219
--- /dev/null
+++ b/l10n-cy/mail/branding/thunderbird/brand.properties
@@ -0,0 +1,7 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+brandShortName=Thunderbird
+brandShorterName=Thunderbird
+brandFullName=Mozilla Thunderbird
+vendorShortName=Mozilla
diff --git a/l10n-cy/mail/browser/appExtensionFields.ftl b/l10n-cy/mail/browser/appExtensionFields.ftl
new file mode 100644
index 0000000000..e3e9d2afdc
--- /dev/null
+++ b/l10n-cy/mail/browser/appExtensionFields.ftl
@@ -0,0 +1,16 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Theme names and descriptions used in the Themes panel in about:addons
+
+# "Auto" is short for automatic. It can be localized without limitations.
+extension-default-theme-name-auto = Thema'r system — awto
+extension-default-theme-description = Dilynwch osodiadau'r system weithredu am fotymau, dewislenni a ffenestri.
+
+extension-thunderbird-compact-light-name = Golau
+extension-thunderbird-compact-light-description = Thema gyda chynllun lliw golau.
+
+extension-thunderbird-compact-dark-name = Tywyll
+extension-thunderbird-compact-dark-description = Thema sydd â chynllun lliw tywyll.
diff --git a/l10n-cy/mail/browser/branding/brandings.ftl b/l10n-cy/mail/browser/branding/brandings.ftl
new file mode 100644
index 0000000000..9ada8da73a
--- /dev/null
+++ b/l10n-cy/mail/browser/branding/brandings.ftl
@@ -0,0 +1,18 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## The following feature names must be treated as a brand.
+##
+## They cannot be:
+## - Transliterated.
+## - Translated.
+##
+## Declension should be avoided where possible, leaving the original
+## brand unaltered in prominent UI positions.
+##
+## For further details, consult:
+## https://mozilla-l10n.github.io/styleguides/mozilla_general/#brands-copyright-and-trademark
+
+-profiler-brand-name = Firefox Profiler
diff --git a/l10n-cy/mail/chrome/communicator/utilityOverlay.dtd b/l10n-cy/mail/chrome/communicator/utilityOverlay.dtd
new file mode 100644
index 0000000000..71646a9845
--- /dev/null
+++ b/l10n-cy/mail/chrome/communicator/utilityOverlay.dtd
@@ -0,0 +1,43 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- LOCALIZATION NOTE : FILE This file contains the global menu items -->
+
+<!ENTITY fileMenu.label          "Ffeil">
+<!ENTITY fileMenu.accesskey        "F">
+<!ENTITY newMenu.label            "Newydd">
+<!ENTITY newMenu.accesskey          "N">
+
+<!ENTITY editMenu.label          "Golygu">
+<!ENTITY editMenu.accesskey        "G">
+<!ENTITY undoCmd.label            "Dadwneud">
+<!ENTITY undoCmd.accesskey          "u">
+<!ENTITY redoCmd.label            "Ailwneud">
+<!ENTITY redoCmd.accesskey          "A">
+<!ENTITY deleteCmd.label          "Dileu">
+<!ENTITY deleteCmd.accesskey        "D">
+
+<!ENTITY customizeCmd.label "Cyfaddasu">
+<!ENTITY customizeCmd.accesskey "f">
+
+<!ENTITY viewMenu.label          "Golwg">
+<!ENTITY viewMenu.accesskey        "l">
+<!ENTITY viewToolbarsMenu.label        "Barrau Offer">
+<!ENTITY viewToolbarsMenu.accesskey      "B">
+<!ENTITY showTaskbarCmd.label          "Bar Statws">
+<!ENTITY showTaskbarCmd.accesskey        "S">
+
+<!ENTITY closeCmd.label      "Cau">
+<!ENTITY closeCmd.key      "W">
+<!ENTITY closeCmd.accesskey    "u">
+
+<!ENTITY quitApplicationCmd.label  "Gadael">
+<!ENTITY quitApplicationCmd.key    "Q">
+<!ENTITY quitApplicationCmd.accesskey  "G">
+
+<!ENTITY quitApplicationCmdUnix.label  "Gadael">
+<!ENTITY quitApplicationCmdUnix.accesskey  "G">
+
+<!ENTITY quitApplicationCmdMac.label  "Gadael &brandShortName;">
+<!ENTITY quitApplicationCmdMac.accesskey  "G">
diff --git a/l10n-cy/mail/chrome/messenger-mapi/mapi.properties b/l10n-cy/mail/chrome/messenger-mapi/mapi.properties
new file mode 100644
index 0000000000..b85c9e9a31
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-mapi/mapi.properties
@@ -0,0 +1,36 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Mail Integration Dialog
+dialogTitle=%S
+dialogText=Hoffech chi ddefnyddio %S fel eich rhaglen e-bost arferol?\u0020
+newsDialogText=Hoffech chi ddefnyddio %S fel eich rhaglen newyddion arferol?
+feedDialogText=Hoffech chi ddefnyddio %S fel eich casglwr llif arferol?
+checkboxText=Peidio dangos y deialog eto
+setDefaultMail=Nid yw %S wedi'i osod fel eich rhaglen e-bost rhagosodedig.  Hoffech chi ei gwneud yn rhaglen e-bost rhagosodedig?
+setDefaultNews=Nid yw %S wedi'i osod fel eich rhaglen newyddion rhagosodedig.  Hoffech chi ei gwneud yn rhaglen newyddion rhagosodedig?
+setDefaultFeed=Nid yw %S wedi ei osod fel eich rhaglen casglwr llif rhagosodedig.  Hoffech chi ei gwneud yn rhaglen casglwr llif rhagosodedig?
+alreadyDefaultMail=Mae %S eisoes wedi'i gosod fel eich rhaglen e-bost rhagosodedig.
+alreadyDefaultNews=Mae %S eisoes wedi'i gosod fel eich rhaglen newyddion rhagosodedig.
+alreadyDefaultFeed=Mae %S eisoes wedi'i gosod fel eich rhaglen casglwr llif rhagosodedig.
+
+# MAPI Messages
+loginText=Rhowch gyfrinair ar gyfer %S:
+loginTextwithName=Rhowch eich enw defnyddiwr a chyfrinair\u0020
+loginTitle=%S
+PasswordTitle=%S
+
+# MAPI Error Messages
+errorMessage=Nid oedd modd gosod %S fel y rhaglen e-bost rhagosodedig am nad oedd modd diweddaru allwedd yn y gofrestrfa. Gwiriwch gyda'ch gweinyddwr system fod gennych fynediad ysgrifennu i'r gofrestrfa ac yna ceisiwch eto.
+errorMessageNews=Nid oedd modd gosod %S fel y rhaglen newyddion rhagosodedig am nad oedd modd diweddaru allwedd yn y gofrestrfa. Gwiriwch gyda'ch gweinyddwr system fod gennych fynediad ysgrifennu i'r gofrestrfa ac yna ceisiwch eto.
+errorMessageTitle=%S
+
+# MAPI Security Messages
+mapiBlindSendWarning=Mae rhaglen arall yn ceisio anfon e-bost gan ddefnyddio eich proffil defnyddiwr. Ydych chi'n siŵr eich bod eisiau anfon e-bost?
+mapiBlindSendDontShowAgain=Rhybuddio pan fydd rhaglen arall yn ceisio anfon e-bost oddi wrthyf i
+
+#Default Mail Display String
+# localization note, %S is the vendor name
+defaultMailDisplayTitle=%S
+
diff --git a/l10n-cy/mail/chrome/messenger-newsblog/am-newsblog.dtd b/l10n-cy/mail/chrome/messenger-newsblog/am-newsblog.dtd
new file mode 100644
index 0000000000..f1167fa481
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-newsblog/am-newsblog.dtd
@@ -0,0 +1,14 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY biffAll.label                 "Galluogi diweddariad i bob llif">
+<!ENTITY biffAll.accesskey             "G">
+
+<!ENTITY newFeedSettings.label         "Y Gosodiadau Rhagosodedig i Lif Newydd">
+
+<!ENTITY manageSubscriptions.label     "Rheoli Tanysgrifiadau…">
+<!ENTITY manageSubscriptions.accesskey "T">
+
+<!ENTITY feedWindowTitle.label         "Dewin Cyfrif Llif">
+<!ENTITY feeds.accountName             "Blogiau a Llif Newyddion">
diff --git a/l10n-cy/mail/chrome/messenger-newsblog/feed-subscriptions.dtd b/l10n-cy/mail/chrome/messenger-newsblog/feed-subscriptions.dtd
new file mode 100644
index 0000000000..6f3a640ef9
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-newsblog/feed-subscriptions.dtd
@@ -0,0 +1,55 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- Subscription Dialog -->
+<!ENTITY feedSubscriptions.label     "Tanysgrifiad Llif">
+<!ENTITY learnMore.label             "Dysgu rhagor am Llif">
+
+<!ENTITY feedTitle.label             "Teitl:">
+<!ENTITY feedTitle.accesskey         "T">
+
+<!ENTITY feedLocation.label          "URL Llif:">
+<!ENTITY feedLocation.accesskey      "L">
+<!ENTITY feedLocation2.placeholder   "Rhowch URL llif dilys">
+<!ENTITY locationValidate.label      "Dilysu">
+<!ENTITY validateText.label          "Gwirio dilysiad ac estyn url dilys.">
+
+<!ENTITY feedFolder.label            "Cadw erthyglau yn:">
+<!ENTITY feedFolder.accesskey        "e">
+
+<!-- Account Settings and Subscription Dialog -->
+<!ENTITY biffStart.label             "Gwirio am erthyglau newydd bob ">
+<!ENTITY biffStart.accesskey         "e">
+<!ENTITY biffMinutes.label           "munud">
+<!ENTITY biffMinutes.accesskey       "m">
+<!ENTITY biffDays.label              "diwrnod">
+<!ENTITY biffDays.accesskey          "d">
+<!ENTITY recommendedUnits.label      "Argymhelliad y cyhoeddwr:">
+
+<!ENTITY quickMode.label             "Dangos crynodeb erthygl yn lle llwytho tudalen gwe">
+<!ENTITY quickMode.accesskey         "c">
+
+<!ENTITY autotagEnable.label         "Creu tagiau'n awtomatig o enwau &lt;categorïau&gt; llif">
+<!ENTITY autotagEnable.accesskey     "a">
+<!ENTITY autotagUsePrefix.label      "Rhagosod tagiau gyda:">
+<!ENTITY autotagUsePrefix.accesskey  "R">
+<!ENTITY autoTagPrefix.placeholder   "Rhoi rhagosodiad tag">
+
+<!-- Subscription Dialog -->
+<!ENTITY button.addFeed.label        "Ychwanegu">
+<!ENTITY button.addFeed.accesskey    "Y">
+<!ENTITY button.verifyFeed.label     "Dilysu">
+<!ENTITY button.verifyFeed.accesskey "D">
+<!ENTITY button.updateFeed.label     "Diweddaru">
+<!ENTITY button.updateFeed.accesskey "D">
+<!ENTITY button.removeFeed.label     "Tynnu">
+<!ENTITY button.removeFeed.accesskey "T">
+<!ENTITY button.importOPML.label     "Mewnforio">
+<!ENTITY button.importOPML.accesskey "M">
+<!ENTITY button.exportOPML.label     "Allforio">
+<!ENTITY button.exportOPML.accesskey "A">
+<!ENTITY button.exportOPML.tooltip   "Allforiwch Llif gyda strwythur ffolderi; ctrl clic neu ctrl enter i allforio Llif fel rhestr">
+
+<!ENTITY cmd.close.commandKey        "w">
+<!ENTITY button.close.label          "Cau">
diff --git a/l10n-cy/mail/chrome/messenger-newsblog/newsblog.properties b/l10n-cy/mail/chrome/messenger-newsblog/newsblog.properties
new file mode 100644
index 0000000000..a3968ad0cd
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-newsblog/newsblog.properties
@@ -0,0 +1,93 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+subscribe-validating-feed=Dilysu'r llif…
+subscribe-cancelSubscription=Ydych chi'n siŵr eich bod am ddileu tanysgrifio i'r llif cyfredol?
+subscribe-cancelSubscriptionTitle=Tanysgrifio i Lif…
+subscribe-feedAlreadySubscribed=Mae gennych eisoes danysgrifiad i'r llif hwn.
+subscribe-errorOpeningFile=Methu agor y ffeil.
+subscribe-feedAdded=Wedi ychwanegu llif.
+subscribe-feedUpdated=Llif wedi ei ddiweddaru.
+subscribe-feedMoved=Tanysgrifiad llif wedi'i symud.
+subscribe-feedCopied=Wedi copïo tanysgrifiad llif.
+subscribe-feedRemoved=Dad-danysgrifio llif.
+subscribe-feedNotValid=Nid yw URL y llif yn ddilys.
+subscribe-feedVerified=Mae'r URL llif wedi ei ddilysu.
+subscribe-networkError=Nid oedd modd canfod URL y Llif. Gwiriwch yr enw a cheisio eto.
+subscribe-noAuthError=Nid yw'r URL llif wedi ei awdurdodi.
+subscribe-loading=Llwytho, arhoswch…
+
+subscribe-OPMLImportTitle=Dewis ffeil OPML i'w mewnforio
+## LOCALIZATION NOTE(subscribe-OPMLExportTitleList):
+## %S is the name of the feed account folder name.
+subscribe-OPMLExportTitleList=Allforio %S fel ffeil OPML- Rhestr Llif
+## LOCALIZATION NOTE(subscribe-OPMLExportTitleStruct):
+## %S is the name of the feed account folder name.
+subscribe-OPMLExportTitleStruct=Allforio %S fel ffeil OPML- Llif gyda strwythur ffolderi
+## LOCALIZATION NOTE(subscribe-OPMLExportFileDialogTitle):
+## %1$S is the brandShortName, %2$S is the name of the feed account folder name.
+subscribe-OPMLExportFileDialogTitle=%1$S Allforio OPML - %2$S
+## LOCALIZATION NOTE(subscribe-OPMLExportDefaultFileName):
+## %1$S is the brandShortName (Thunderbird for example), %2$S is the account name.
+## The default extension (.opml) is added here as it is not automatically appended in the file picker on MacOS.
+subscribe-OPMLExportDefaultFileName=My%1$SFeeds-%2$S.opml
+## LOCALIZATION NOTE(subscribe-OPMLImportInvalidFile): %S is the name of the OPML file the user tried to import.
+subscribe-OPMLImportInvalidFile=Nid yw ffeil %S i weld yn ffeil OPML dilys.
+## LOCALIZATION NOTE(subscribe-OPMLImportFeedCount): Semi-colon list of plural forms.
+## See: http://developer.mozilla.org/en/docs/Localization_and_Plurals
+## #1 is the count of new imported entries.
+subscribe-OPMLImportFeedCount=Heb fewnforio llifau newydd.;Mewnforiwyd #1 llif newydd.;Mewnforiwyd #1 llif newydd.;Mewnforiwyd #1 llif newydd.;Mewnforiwyd #1 llif newydd.;Mewnforiwyd #1 llif newydd.
+## LOCALIZATION NOTE(subscribe-OPMLImportUniqueFeeds): Semi-colon list of plural forms.
+## #1 is the count of new imported entries
+subscribe-OPMLImportUniqueFeeds=Mewnforiwyd #1 llif newydd nad ydych wedi tanysgrifio iddynt hyd yn hyn;Mewnforiwyd #1 llif newydd nad ydych wedi tanysgrifio iddynt hyd yn hyn
+## LOCALIZATION NOTE(subscribe-OPMLImportFoundFeeds):
+## #1 is total number of elements found in the file
+subscribe-OPMLImportFoundFeeds=(allan o #1 enghraifft a gafwyd);(allan o #1 enghraifft a gafwyd)
+## LOCALIZATION NOTE(subscribe-OPMLImportStatus):
+## This is the concatenation of the two strings defined above to compose 1 sentence.
+## %1$S = subscribe-OPMLImportUniqueFeeds
+## %2$S = subscribe-OPMLImportFoundFeeds
+subscribe-OPMLImportStatus=%1$S %2$S.
+
+subscribe-OPMLExportOPMLFilesFilterText=Ffeiliau OPML
+## LOCALIZATION NOTE(subscribe-OPMLExportDone): %S is the export file name.
+subscribe-OPMLExportDone=Mae llif o'r cyfrif hwn wedi eu hallforio i %S.
+
+subscribe-confirmFeedDeletionTitle=Tynnu Llif
+## LOCALIZATION NOTE(subscribe-confirmFeedDeletion): %S is the name of the feed the user wants to unsubscribe from.
+subscribe-confirmFeedDeletion=Ydych chi'n siŵr eich bod am ddad-danysgrifio o lif : \n %S?
+
+## LOCALIZATION NOTE(subscribe-gettingFeedItems):
+##  - The first %S is the number of articles processed so far;
+##  - The second %S is the total number of items
+subscribe-gettingFeedItems=Llwytho i lawr erthyglau llif (%S of %S)…
+
+newsblog-noNewArticlesForFeed=Nid oes erthyglau newydd i'r llif hwn.
+## LOCALIZATION NOTE(newsblog-networkError): %S is the feed URL
+newsblog-networkError=Nid oedd modd canfod %S. Gwiriwch yr enw a cheisio eto.
+## LOCALIZATION NOTE(newsblog-feedNotValid): %S is the feed URL
+newsblog-feedNotValid=Nid yw %S yn llif ddilys.
+## LOCALIZATION NOTE(newsblog-badCertError): %S is the feed URL host
+newsblog-badCertError=Mae %S yn defnyddio tystysgrif diogelwch annilys.
+## LOCALIZATION NOTE(newsblog-noAuthError): %S is the feed URL
+newsblog-noAuthError=Nid yw %S wedi ei awdurdodi.
+newsblog-getNewMsgsCheck=Gwirio'r llif am eitemau newydd…
+
+## LOCALIZATION NOTE(feeds-accountname): This string should be the same as feeds.accountName in am-newsblog.dtd
+feeds-accountname=Blogiau a Llif Newyddion
+
+## LOCALIZATION NOTE(externalAttachmentMsg): Content in the MIME part for external link attachments.
+externalAttachmentMsg=Mae'r atodiad MIME hwn wedi ei gadw ar wahân o'r neges.
+
+## Import wizard.
+ImportFeedsCreateNewListItem=* Cyfrif Newydd *
+ImportFeedsNewAccount=Creu a mewnforio i gyfrif Llif newydd
+ImportFeedsExistingAccount=Mewnforio i gyfrif Llif cyfredol
+## LOCALIZATION NOTE(ImportFeedsDone):
+##  - The first %S is the import file name;
+##  - The second %S is the value of either ImportFeedsNew or ImportFeedsExisting;
+##  - The third %S is the feed account name.
+ImportFeedsNew=newydd
+ImportFeedsExisting=cyfredol
+ImportFeedsDone=Mae mewnforio tanysgrifiadau llif wedi o ffeil %1$S i gyfrif %2$S '%3$S' wedi ei gwblhau.
diff --git a/l10n-cy/mail/chrome/messenger-region/region.properties b/l10n-cy/mail/chrome/messenger-region/region.properties
new file mode 100644
index 0000000000..c1882eb25b
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-region/region.properties
@@ -0,0 +1,29 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# To make mapit buttons to disappear in the addressbook, specify empty string.  For example:
+# mail.addr_book.mapit_url.format=
+# The mail.addr_book.mapit_url.format should start with the URL of the mapping
+# service and then the query part with placeholders to be subsituted from values
+# from the addressbook contact's address.
+# Available placeholders are:
+# @A1 == address, part 1
+# @A2 == address, part 2
+# @CI == city
+# @ST == state
+# @ZI == zip code
+# @CO == country
+# Default map service:
+mail.addr_book.mapit_url.format=https://maps.google.com/maps?q=@A1%20@A2%20@CI%20@ST%20@ZI%20@CO
+# List of available map services (up to 5 can be defined here):
+mail.addr_book.mapit_url.1.name=Google Maps
+mail.addr_book.mapit_url.1.format=https://maps.google.com/maps?q=@A1%20@A2%20@CI%20@ST%20@ZI%20@CO
+mail.addr_book.mapit_url.2.name=OpenStreetMap
+mail.addr_book.mapit_url.2.format=https://nominatim.openstreetmap.org/search.php?polygon=1&q=@A1%2C@A2%2C@CI%2C@ST%2C@ZI%2C@CO
+
+mailnews.messageid_browser.url=http://groups.google.com/search?as_umsgid=%mid
+
+# Recognize non-standard versions of "Re:" in subjects from localized versions of MS Outlook et al.
+# Specify a comma-separated list without spaces. For example: mailnews.localizedRe=AW,SV
+mailnews.localizedRe=
diff --git a/l10n-cy/mail/chrome/messenger-smime/certFetchingStatus.dtd b/l10n-cy/mail/chrome/messenger-smime/certFetchingStatus.dtd
new file mode 100644
index 0000000000..6ab452d224
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-smime/certFetchingStatus.dtd
@@ -0,0 +1,10 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE shown while obtaining certificates from a directory -->
+
+
+<!ENTITY title.label "Llwytho Tystysgrifau i Lawr">
+<!ENTITY info.message "Chwilio'r cyfeiriadur am dystysgrifau derbynwyr. Gall hyn gymryd ychydig o funudau.">
+<!ENTITY stop.label "Atal y Chwilio">
diff --git a/l10n-cy/mail/chrome/messenger-smime/msgCompSMIMEOverlay.dtd b/l10n-cy/mail/chrome/messenger-smime/msgCompSMIMEOverlay.dtd
new file mode 100644
index 0000000000..020a713182
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-smime/msgCompSMIMEOverlay.dtd
@@ -0,0 +1,16 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE msgCompSMIMEOverlay.dtd UI for s/mime hooks in message composition -->
+
+<!-- not yet used
+<!ENTITY menu_securityEncryptOptional.label "Allow Encryption">
+<!ENTITY menu_securityEncryptOptional.accesskey "w">
+-->
+
+<!ENTITY menu_techPGP.label "OpenPGP">
+<!ENTITY menu_techPGP.accesskey "O">
+<!ENTITY menu_techSMIME.label "S/MIME">
+<!ENTITY menu_techSMIME.accesskey "S">
+
diff --git a/l10n-cy/mail/chrome/messenger-smime/msgCompSecurityInfo.dtd b/l10n-cy/mail/chrome/messenger-smime/msgCompSecurityInfo.dtd
new file mode 100644
index 0000000000..3c1dbc4285
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-smime/msgCompSecurityInfo.dtd
@@ -0,0 +1,19 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE msgCompSecurityInfo.dtd UI for viewing security status when composing a message -->
+
+
+<!ENTITY title.label "Diogelwch Neges">
+<!ENTITY subject.plaintextWarning "Sylw: Nid yw llinellau pwnc neges e-bost byth yn cael eu hamgryptio.">
+<!ENTITY status.heading "Bydd cynnwys eich neges yn cael ei hanfon fel a ganlyn:">
+<!ENTITY status.signed "Llofnod ddigidol:">
+<!ENTITY status.encrypted "Amgryptiad:">
+<!ENTITY status.certificates "Tystysgrifau:">
+<!ENTITY view.label "Golwg">
+<!ENTITY view.accesskey "l">
+<!ENTITY tree.recipient "Derbynnydd">
+<!ENTITY tree.status "Statws">
+<!ENTITY tree.issuedDate "Cyhoeddwyd">
+<!ENTITY tree.expiresDate "Daw i Ben">
diff --git a/l10n-cy/mail/chrome/messenger-smime/msgCompSecurityInfo.properties b/l10n-cy/mail/chrome/messenger-smime/msgCompSecurityInfo.properties
new file mode 100644
index 0000000000..e9e6e5b19e
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-smime/msgCompSecurityInfo.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+StatusNotFound=Heb Ganfod
+StatusValid=Dilys
+StatusExpired=Daeth i Ben
+StatusUntrusted=Dim Ymddiriedaeth
+StatusRevoked=Diddymwyd
+StatusInvalid=Annilys
+StatusYes=Iawn
+StatusNo=Na
+StatusNotPossible=Ddim yn bosib
diff --git a/l10n-cy/mail/chrome/messenger-smime/msgReadSMIMEOverlay.properties b/l10n-cy/mail/chrome/messenger-smime/msgReadSMIMEOverlay.properties
new file mode 100644
index 0000000000..90b8248152
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-smime/msgReadSMIMEOverlay.properties
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+ImapOnDemand=Mae'r neges hon wedi ei llofnodi'n ddigidol, ond nid yw ei holl atodiadau wedi eu llwytho i lawr eto. Felly nid oes modd dilysu'r llofnod. Cliciwch Iawn i lwytho i lawr y neges gyflawn a dilysu'r llofnod.
+#
+#NOTE To translater, anything between %..% and <..> should not be translated.
+# the former will be replaced by java script, and the latter is HTML formatting.
+#
+CantDecryptTitle=Nid yw %brand% yn gallu dadgryptio'r neges hon
+CantDecryptBody=Mae'r anfonwr wedi amgryptio'r neges hon gan ddefnyddio un o'ch tystysgrifau digidol, er hynny, nid yw %brand% yn gallu dod o hyn i'r dystysgrif a'r allwedd breifat cyfatebol. <br> Atebion posib: <br><ul><li>Os oes gennych gerdyn clyfar, rhowch hwnnw i fewn. <li>Os ydych yn defnyddio peiriant newydd neu yn defnyddio proffil newydd %brand% , bydd angen i chi adfer eich tystysgrif a'ch allwedd breifat o gopi wrth gefn. Mae copïau wrth gefn o dystysgrifau yn gorffen gyda ".p12".</ul>\u0020
diff --git a/l10n-cy/mail/chrome/messenger-smime/msgReadSecurityInfo.dtd b/l10n-cy/mail/chrome/messenger-smime/msgReadSecurityInfo.dtd
new file mode 100644
index 0000000000..26c71b0c26
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-smime/msgReadSecurityInfo.dtd
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE msgReadSecurityInfo.dtd UI for viewing security status when reading a received message -->
+
+<!ENTITY status.label "Diogelwch Neges">
+<!ENTITY signatureCert.label "Gweld Llofneo Tystysgrif">
+<!ENTITY encryptionCert.label "Gweld Tystysgrif Amgryptio">
+
+<!ENTITY signer.name "Llofnod gan:">
+<!ENTITY recipient.name "Amgryptio ar gyfer:">
+<!ENTITY email.address "Cyfeiriad e-bost:">
+<!ENTITY issuer.name "Tystysgrif wedi'i ryddhau gan:">
+
+<!-- LOCALIZATION NOTE(SMIME.label): This a name for a technical standard. You should not translate it, but if applicable, you may write it using localized characters. -->
+<!ENTITY SMIME.label "S/MIME">
diff --git a/l10n-cy/mail/chrome/messenger-smime/msgSecurityInfo.properties b/l10n-cy/mail/chrome/messenger-smime/msgSecurityInfo.properties
new file mode 100644
index 0000000000..7b45babf57
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger-smime/msgSecurityInfo.properties
@@ -0,0 +1,36 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+## Signature Information strings
+SINoneLabel=Nid oes gan y Neges Dystysgrif Ddigidol
+SINone=Nid yw'r neges yn cynnwys llofnod digidol yr anfonwr. Mae absenoldeb y llofnod digidol yn golygu bod modd i'r neges ddod gan rywun sy'n cogio mai ei gyfeiriad e-bost yw hwn. Mae hefyd yn bosibl fod y neges wedi cael ei newid wrth deithio ar draws y rhwydwaith. Er hynny, mae'n annhebygol fod yr un o'r ddau wedi digwydd.
+SIValidLabel=Mae'r Neges wedi'i Llofnodi
+SIValid=Mae'r neges yn cynnwys llofnod digidol dilys. Nid yw'r neges wedi'i newid ers iddi gael ei hanfon.
+SIInvalidLabel=Nid yw'r Llofnod Digidol yn Ddilys
+SIInvalidHeader=Mae'r neges yn cynnwys llofnod digidol, ond mae'r llofnod yn annilys.
+SIContentAltered=Nid yw'r llofnod yn cydweddu'n union â chynnwys y neges. Mae'n ymddangos fod y neges wedi'i newid ar ôl i'r anfonwr ei llofnod. Peidiwch ag ymddiried yn nilysrwydd y neges cyn gwirio ei gynnwys gyda'r anfonwr.
+SIExpired=Mae'n ymddangos bod y dystysgrif gafodd ei defnyddio i lofnodi'r neges wedi dod i ben. Gwnewch yn siŵr bod cloc eich cyfrifiadur wedi'i osod yn gywir.
+SIRevoked=Mae'r dystysgrif sydd wedi ei defnyddio i lofnodi'r neges wedi'i ddiddymu. Peidiwch ag ymddiried yn nilysrwydd y neges nes i chi wirio'r cynnwys gyda'r anfonwr.
+SINotYetValid=Nid yw'r dystysgrif sydd wedi'i defnyddio i lofnodi'r neges yn ymddangos yn ddilys. Gwnewch yn siŵr fod eich cloc wedi ei osod yn gywir.
+SIUnknownCA=Mae'r dystysgrif gafodd ei defnyddio i lofnodi'r neges wedi'i chyhoeddi gan awdurdod tystysgrif anhysbys.
+SIUntrustedCA=Mae'r dystysgrif gafodd ei defnyddio i lofnodi'r neges wedi'i chyhoeddi gan awdurdod tystysgrif nad ydych yn ymddiried ynddo i gyhoeddi'r math yma o dystysgrif.
+SIExpiredCA=Mae'r dystysgrif rydych yn ei defnyddio i lofnodi'r neges wedi'i chyhoeddi gan awdurdod tystysgrif mae eu tystysgrif wedi dod i ben. Gwnewch yn siŵr fod cloc eich cyfrifiadur wedi ei osod yn gywir.
+SIRevokedCA=Mae'r dystysgrif a ddefnyddiwyd i lofnodi'r neges wedi'i chyhoeddi gan awdurdod tystysgrif y mae ei dystysgrif ei hun wedi ei ddiddymu. Peidiwch ag ymddiried yn nilysrwydd y neges cyn gwirio ei gynnwys gyda'r anfonwr.
+SINotYetValidCA=Cafodd y dystysgrif a ddefnyddiwyd i lofnodi'r neges ei chyhoeddi gan awdurdod tystysgrif nad yw eu tystysgrif eto'n ddilys. Gwnewch yn siŵr fod eich cloc wedi'i osod yn gywir.
+SIInvalidCipher=Mae'r neges wedi'i llofnodi gan ddefnyddio cryfder amgryptio nad yw'r fersiwn hwn o'ch meddalwedd yn ei gynnal.
+SIClueless=Mae anawsterau anhysbys i'r llofnod digidol hwn. Peidiwch ag ymddiried yn nilysrwydd y neges nes i chi wirio ei chynnwys gyda'r anfonwr.
+SIPartiallyValidLabel=Neges wedi'i llofnodi
+SIPartiallyValidHeader=Er bod y llofnod digidol yn ddilys, mae'n anhysbys os yw'r anfonwr a'r llofnod yr un.
+SIHeaderMismatch=Mae'r cyfeiriad e-bost nodwyd yn nhystysgrif y llofnodwr yn wahanol i'r cyfeiriad e-bost a ddefnyddiwyd i anfon y neges. Edrychwch ar fanylion y dystysgrif llofnod i weld pwy wnaeth lofnodi'r neges.
+SICertWithoutAddress=Nid yw'r dystysgrif a ddefnyddiwyd i lofnodi'r neges yn cynnwys cyfeiriad e-bost. Edrychwch ar fanylion y dystysgrif llofnod i weld pwy wnaeth ei llofnodi.
+
+## Encryption Information strings
+EINoneLabel2=Nid yw'r Neges wedi'i Hamgryptio
+EINone=Nid yw'r neges hon wedi'i hamgryptio cyn ei hanfon. Mae modd i eraill weld negeseuon sy'n cael eu hanfon ar draws y rhyngrwyd ac sydd heb eu hamgryptio.
+EIValidLabel=Mae'r Neges wedi'i Hamgryptio
+EIValid=Cafodd y neges ei hamgryptio cyn ei hanfon atoch. Mae amgryptio'n ei gwneud yn anodd iawn i bobl eraill edrych ar wybodaeth wrth iddo deithio ar draws y rhwydwaith.
+EIInvalidLabel=Nid Oes Modd Dadgryptio'r Neges
+EIInvalidHeader=Mae'r neges wedi'i hamgryptio cyn ei hanfon atoch, ond nid oes modd ei dadgryptio.
+EIContentAltered=Mae'n ymddangos bod cynnwys y neges wedi'i newid yn ystod y trosglwyddiad.
+EIClueless=Mae yna anawsterau anhysbys gyda'r neges wedi'i hamgryptio.
diff --git a/l10n-cy/mail/chrome/messenger/AccountManager.dtd b/l10n-cy/mail/chrome/messenger/AccountManager.dtd
new file mode 100644
index 0000000000..0e8df605f3
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/AccountManager.dtd
@@ -0,0 +1,25 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- extracted from AccountManager.xhtml -->
+
+<!ENTITY accountManagerTitle.label "Gosodiadau'r Cyfrif">
+<!ENTITY  accountManagerCloseButton.label "Cau">
+
+<!ENTITY accountActionsButton.label "Gweithredoedd Cyfrif">
+<!ENTITY accountActionsButton.accesskey "G">
+<!ENTITY addMailAccountButton.label "Ychwanegu Cyfrif E-bost…">
+<!ENTITY addMailAccountButton.accesskey "E">
+<!ENTITY addIMAccountButton.label "Ychwanegu Cyfrif Sgwrsio…">
+<!ENTITY addIMAccountButton.accesskey "S">
+<!ENTITY addFeedAccountButton.label "Ychwanegu Cyfrif Llif…">
+<!ENTITY addFeedAccountButton.accesskey "L">
+<!ENTITY setDefaultButton.label "Gosod fel y Rhagosodiad">
+<!ENTITY setDefaultButton.accesskey "R">
+<!ENTITY removeButton.label "Tynnu Cyfrif">
+<!ENTITY removeButton.accesskey "T">
+
+<!ENTITY addonsButton.label "Estyniadau a Themâu">
+
+<!-- AccountManager.xhtml -->
diff --git a/l10n-cy/mail/chrome/messenger/AccountWizard.dtd b/l10n-cy/mail/chrome/messenger/AccountWizard.dtd
new file mode 100644
index 0000000000..5f53834437
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/AccountWizard.dtd
@@ -0,0 +1,55 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- Entities for AccountWizard -->
+
+<!ENTITY windowTitle.label "Dewin Cyfrif">
+<!ENTITY accountWizard.size "width: 40em; height: 38em;">
+
+<!-- Entities for Account Type page -->
+
+<!-- Entities for Identity page -->
+
+<!ENTITY identityTitle.label "Hunaniaeth">
+<!ENTITY identityDesc.label "Mae gan bob cyfrif enw, sef y wybodaeth sy'n eich enwi i eraill sy'n derbyn negeseuon gennych.">
+
+<!-- LOCALIZATION NOTE (fullnameDesc.label) : do not translate two of "&quot;" in below line -->
+<!ENTITY fullnameDesc.label "Rhowch yr enw yr hoffech iddo ymddangos ym maes &quot;Oddi wrth&quot; y negeseuon fyddwch yn eu hanfon">
+<!-- LOCALIZATION NOTE (fullnameExample.label) : use following directions for below line
+  1, do not translate two of "&quot;"
+  2, Use localized full name instead of "John Smith"
+-->
+<!ENTITY fullnameExample.label "(er enghraifft., &quot;John Jones&quot;).">
+<!ENTITY fullnameLabel.label "Eich Enw:">
+<!ENTITY fullnameLabel.accesskey "E">
+
+<!ENTITY emailLabel.label "Cyfeiriad E-bost:">
+<!ENTITY emailLabel.accesskey "b">
+
+<!-- Entities for Incoming Server page -->
+
+<!ENTITY incomingTitle.label "Gwybodaeth Gweinydd Derbyn">
+<!ENTITY incomingUsername.label "Enw Defnyddiwr:">
+<!-- LOCALIZATION NOTE (newsServerNameDesc.label) : Do not translate "NNTP" or the "&quot;" entities in below line -->
+<!ENTITY newsServerNameDesc.label "Rhowch enw eich gweinydd newyddion (NNTP). (e.e., &quot;news.esiampl.net&quot;).">
+<!ENTITY newsServerLabel.label "Gweinydd Grŵp Newyddion:">
+<!ENTITY newsServerLabel.accesskey "G">
+
+<!-- Entities for Outgoing Server page -->
+
+<!-- Entities for Account name page -->
+
+<!ENTITY accnameTitle.label "Enw Cyfrif">
+<!-- LOCALIZATION NOTE (accnameDesc.label) : do not translate any "&quot;" in below line -->
+<!ENTITY accnameDesc.label "Rhowch yr enw yr hoffech gyfeirio at y cyfrif. (e.e. &quot;Cyfrif Gwaith&quot;, &quot;Cyfrif Cartref&quot; neu &quot;Cyfrif Newyddion&quot;).">
+<!ENTITY accnameLabel.label "Enw Cyfrif:">
+<!ENTITY accnameLabel.accesskey "E">
+
+<!-- Entities for Done (Congratulations) page -->
+
+<!ENTITY completionTitle.label "Llongyfarchiadau!">
+<!ENTITY completionText.label "Rydych wedi rhoi'r holl wybodaeth angenrheidiol ar gyfer creu'r cyfrif.">
+<!ENTITY newsServerNamePrefix.label "Enw Gweinydd Grwpiau Newyddion (NNTP):">
+<!ENTITY clickFinish.label "Cliciwch Gorffen i gadw'r gosodiadau a gadael y Dewin Cyfrif.">
+<!ENTITY clickFinish.labelMac "Cliciwch Gorffen i gadw'r gosodiadau a gadael y Dewin Cyfrif.">
diff --git a/l10n-cy/mail/chrome/messenger/CustomHeaders.dtd b/l10n-cy/mail/chrome/messenger/CustomHeaders.dtd
new file mode 100644
index 0000000000..f2167621cc
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/CustomHeaders.dtd
@@ -0,0 +1,11 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY window.title "Cyfaddasu Penynnau">
+<!ENTITY addButton.label "Ychwanegu">
+<!ENTITY addButton.accesskey "a">
+<!ENTITY removeButton.label "Tynnu">
+<!ENTITY removeButton.accesskey "T">
+<!ENTITY newMsgHeader.label "Pennyn neges newydd:">
+<!ENTITY newMsgHeader.accesskey "P">
diff --git a/l10n-cy/mail/chrome/messenger/FilterEditor.dtd b/l10n-cy/mail/chrome/messenger/FilterEditor.dtd
new file mode 100644
index 0000000000..0e5c8c92a7
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/FilterEditor.dtd
@@ -0,0 +1,67 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY window.title "Rheolau Hidlo">
+<!ENTITY filterName.label "Enw'r hidl:">
+<!ENTITY filterName.accesskey "E">
+
+<!ENTITY junk.label "Sbam">
+<!ENTITY notJunk.label "Nid Sbam">
+
+<!ENTITY lowestPriorityCmd.label "Isaf">
+<!ENTITY lowPriorityCmd.label "Isel">
+<!ENTITY normalPriorityCmd.label "Arferol">
+<!ENTITY highPriorityCmd.label "Uchel">
+<!ENTITY highestPriorityCmd.label "Uchaf">
+
+<!ENTITY contextDesc.label "Gosod yr hidl pan yn:">
+<!ENTITY contextIncomingMail.label "Estyn E-bost Newydd:">
+<!ENTITY contextIncomingMail.accesskey "E">
+<!ENTITY contextManual.label "Rhedeg â Llaw">
+<!ENTITY contextManual.accesskey "L">
+<!ENTITY contextBeforeCls.label "Hidlo cyn Dynodi fel Sbam">
+<!ENTITY contextAfterCls.label "Hidlo ar ôl Dynodi fel Sbam">
+<!ENTITY contextOutgoing.label "Ar ôl Anfon">
+<!ENTITY contextOutgoing.accesskey "n">
+<!ENTITY contextArchive.label "Archifo">
+<!ENTITY contextArchive.accesskey "A">
+
+<!ENTITY contextPeriodic.accesskey "e">
+
+<!ENTITY filterActionDesc.label "Gwneud hyn:">
+<!ENTITY filterActionDesc.accesskey "G">
+
+<!ENTITY filterActionOrderWarning.label "Sylw: Bydd gweithredoedd hidlo'n cael eu rhedeg mewn trefn gwahanol.">
+<!ENTITY filterActionOrder.label "Gw. trefn weithredu">
+
+<!-- New Style Filter Rule Actions -->
+<!ENTITY moveMessage.label "Symud Neges i">
+<!ENTITY copyMessage.label "Copïo Neges i">
+<!ENTITY forwardTo.label "Anfon Neges Ymlaen i">
+<!ENTITY replyWithTemplate.label "Ateb gyda Thempled">
+<!ENTITY markMessageRead.label "Marcio wedi Darllen">
+<!ENTITY markMessageUnread.label "Marcio Heb ei Ddarllen">
+<!ENTITY markMessageStarred.label "Ychwanegu Seren">
+<!ENTITY setPriority.label "Gosod Blaenoriaeth i">
+<!ENTITY addTag.label "Tagio Neges">
+<!ENTITY setJunkScore.label "Gosod Statws Sbam i">
+<!ENTITY deleteMessage.label "Dileu Neges">
+<!ENTITY deleteFromPOP.label "Dileu o'r Gweinydd POP">
+<!ENTITY fetchFromPOP.label "Estyn o'r Gweinydd POP">
+<!ENTITY ignoreThread.label "Anwybyddu'r Edefyn">
+<!ENTITY ignoreSubthread.label "Anwybyddu'r Is-edefyn">
+<!ENTITY watchThread.label "Gwylio'r Edefyn">
+<!ENTITY stopExecution.label "Atal Gweithredu'r Hidl">
+
+<!ENTITY addAction.tooltip "Ychwanegu gweithred newydd">
+<!ENTITY removeAction.tooltip "Tynnu'r weithred hon">
+
+<!-- LOCALIZATION NOTE
+     The values below are used to control the widths of the filter action widgets.
+     Change the values only when the localized strings in the popup menus
+     are truncated in the widgets.
+  -->
+<!-- Flex Attribute: https://developer.mozilla.org/docs/XUL/Attribute/flex -->
+<!ENTITY filterActionTypeFlexValue "1">
+<!ENTITY filterActionTargetFlexValue "4">
diff --git a/l10n-cy/mail/chrome/messenger/FilterListDialog.dtd b/l10n-cy/mail/chrome/messenger/FilterListDialog.dtd
new file mode 100644
index 0000000000..781665cd40
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/FilterListDialog.dtd
@@ -0,0 +1,41 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY window.title "Hidlau Negeseuon">
+<!ENTITY nameColumn.label "Enw Hidl">
+<!ENTITY activeColumn.label "Galluogwyd">
+<!ENTITY newButton.label "Newydd…">
+<!ENTITY newButton.accesskey "N">
+<!ENTITY newButton.popupCopy.label "Copïo…">
+<!ENTITY newButton.popupCopy.accesskey "C">
+<!ENTITY editButton.label "Golygu…">
+<!ENTITY editButton.accesskey "G">
+<!ENTITY deleteButton.label "Dileu">
+<!ENTITY deleteButton.accesskey "D">
+<!ENTITY reorderTopButton "Symud i'r Brig">
+<!ENTITY reorderTopButton.accessKey "B">
+<!ENTITY reorderTopButton.toolTip "Ad-drefnu'r hidl fel ei fod yn gweithredu cyn pob un arall">
+<!ENTITY reorderUpButton.label "Symud i Fyny">
+<!ENTITY reorderUpButton.accesskey "F">
+<!ENTITY reorderDownButton.label "Symud i Lawr">
+<!ENTITY reorderDownButton.accesskey "L">
+<!ENTITY reorderBottomButton "Symud i'r Gwaelod">
+<!ENTITY reorderBottomButton.accessKey "w">
+<!ENTITY reorderBottomButton.toolTip "Ad-drefnu'r hidl fel ei fod yn gweithredu ar ôl pob un arall">
+<!ENTITY filterHeader.label "Bydd hidlau sydd wedi'u galluogi yn rhedeg yn awtomatig yn ôl y drefn â nodir isod.">
+<!ENTITY filtersForPrefix.label "Hidlau ar gyfer:">
+<!ENTITY filtersForPrefix.accesskey "H">
+<!ENTITY viewLogButton.label "Cofnod Hidl">
+<!ENTITY viewLogButton.accesskey "C">
+<!ENTITY runFilters.label "Rhedeg Nawr">
+<!ENTITY runFilters.accesskey "R">
+<!ENTITY stopFilters.label "Atal">
+<!ENTITY stopFilters.accesskey "A">
+<!ENTITY folderPickerPrefix.label "Rhedeg yr hidl(au) ar:">
+<!ENTITY folderPickerPrefix.accesskey "R">
+<!ENTITY helpButton.label "Cymorth">
+<!ENTITY helpButton.accesskey "y">
+<!ENTITY closeCmd.key "W"> 
+<!ENTITY searchBox.emptyText "Chwilio yn ôl enw…">
+
diff --git a/l10n-cy/mail/chrome/messenger/SearchDialog.dtd b/l10n-cy/mail/chrome/messenger/SearchDialog.dtd
new file mode 100644
index 0000000000..c575b26463
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/SearchDialog.dtd
@@ -0,0 +1,41 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- for SearchDialog.xul -->
+
+<!ENTITY searchHeading.label         "Chwilio am negeseuon yn:">
+<!ENTITY searchHeading.accesskey     "h">
+<!ENTITY searchSubfolders.label      "Chwilio is-ffolderi">
+<!ENTITY searchSubfolders.accesskey  "w">
+<!ENTITY searchOnServer.label        "Rhedeg chwilio ar weinydd">
+<!ENTITY searchOnServer.accesskey    "R">
+<!ENTITY resetButton.label           "Clirio">
+<!ENTITY resetButton.accesskey       "C">
+<!ENTITY openButton.label            "Agor">
+<!ENTITY openButton.accesskey        "A">
+<!ENTITY deleteButton.label          "Dileu">
+<!ENTITY deleteButton.accesskey      "D">
+<!ENTITY searchDialogTitle.label     "Chwilio drwy'r Negeseuon">
+<!ENTITY results.label               "Canlyniadau">
+<!ENTITY moveButton.label            "Symud I">
+<!ENTITY moveButton.accesskey        "I">
+<!ENTITY closeCmd.key                "W"> 
+<!ENTITY openInFolder.label          "Agor yn Ffolder">
+<!ENTITY openInFolder.accesskey      "A">
+<!ENTITY saveAsVFButton.label        "Cadw fel Ffolder Chwilio">
+<!ENTITY saveAsVFButton.accesskey    "a">
+<!-- for ABSearchDialog.xul -->
+
+<!ENTITY abSearchHeading.label       "Chwilio yn:">
+<!ENTITY abSearchHeading.accesskey   "h">
+<!ENTITY propertiesButton.label      "Priodweddau">
+<!ENTITY propertiesButton.accesskey  "P">
+<!ENTITY composeButton.label         "Ysgrifennu">
+<!ENTITY composeButton.accesskey     "Y">
+<!ENTITY deleteCardButton.label      "Dileu">
+<!ENTITY deleteCardButton.accesskey  "D">
+<!ENTITY abSearchDialogTitle.label   "Chwilio Uwch drwy'r Llyfr Cyfeiriadau">
+<!-- Thread Pane -->
+
+<!-- Thread Pane Tooltips -->
+
diff --git a/l10n-cy/mail/chrome/messenger/aboutDialog.dtd b/l10n-cy/mail/chrome/messenger/aboutDialog.dtd
new file mode 100644
index 0000000000..bb7d182fa3
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/aboutDialog.dtd
@@ -0,0 +1,116 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY aboutDialog.title          "Ynghylch &brandFullName;">
+
+<!-- LOCALIZATION NOTE (update.*):
+# These strings are also used in the update pane of preferences.
+# See about:preferences#advanced.
+-->
+<!-- LOCALIZATION NOTE (update.checkForUpdatesButton.*, update.updateButton.*):
+# Only one button is present at a time.
+# The button when displayed is located directly under the Thunderbird version in
+# the about dialog.
+-->
+<!ENTITY update.checkForUpdatesButton.label       "Gwirio am Ddiweddariadau">
+<!ENTITY update.checkForUpdatesButton.accesskey   "D">
+<!ENTITY update.updateButton.label3               "Ailgychwyn i ddiweddaru &brandShorterName;">
+<!ENTITY update.updateButton.accesskey            "A">
+
+
+<!-- LOCALIZATION NOTE (warningDesc.version): This is a warning about the experimental nature of Nightly builds. It is only shown in this version. -->
+<!ENTITY warningDesc.version        "Mae &brandShortName; yn arbrofol a gall fod yn ansad.">
+<!-- LOCALIZATION NOTE (warningDesc.telemetryDesc): This is a notification that Nightly builds automatically send Telemetry data back to Mozilla. It is only shown in this version. "It" refers to brandShortName. -->
+<!ENTITY warningDesc.telemetryDesc  "Mae'n anfon gwybodaeth yn awtomatig am berfformiad, caledwedd, defnydd a chyfaddasu nôl i &vendorShortName; i helpu i wneud &brandShortName; yn well.">
+
+<!-- LOCALIZATION NOTE (community.exp.*) This paragraph is shown in "experimental" builds, i.e. Nightly builds, instead of the other "community.*" strings below. -->
+<!ENTITY community.exp.start        "">
+<!-- LOCALIZATION NOTE (community.exp.mozillaLink): This is a link title that links to https://www.mozilla.org/. -->
+<!ENTITY community.exp.mozillaLink  "Mae &vendorShortName;">
+<!ENTITY community.exp.middle       " yn ">
+<!-- LOCALIZATION NOTE (community.exp.creditslink): This is a link title that links to about:credits. -->
+<!ENTITY community.exp.creditsLink  "gymuned fyd-eang">
+<!ENTITY community.exp.end          " sy'n cydweithio i gadw'r We yn agored, cyhoeddus ac ar gael i bawb.">
+
+<!ENTITY community.start2           "Cynlluniwyd &brandShortName; gan ">
+<!-- LOCALIZATION NOTE (community.mozillaLink): This is a link title that links to https://www.mozilla.org/. -->
+<!ENTITY community.mozillaLink      "&vendorShortName;">
+<!ENTITY community.middle2          ", a ">
+<!-- LOCALIZATION NOTE (community.creditsLink): This is a link title that links to about:credits. -->
+<!ENTITY community.creditsLink      "chymuned fyd-eang">
+<!ENTITY community.end3             " sy'n cydweithio i gadw'r We yn agored, cyhoeddus ac ar gael i bawb.">
+
+<!ENTITY helpus.start               "Hoffech chi helpu? ">
+<!-- LOCALIZATION NOTE (helpus.donateLink): This is a link title that links to the thunderbird donation page -->
+<!ENTITY helpus.donateLink          "Gwnewch gyfraniad">
+<!ENTITY helpus.middle              " neu ">
+<!-- LOCALIZATION NOTE (helpus.getInvolvedLink): This is a link title that links to https://www.thunderbird.net/get-involved/. -->
+<!ENTITY helpus.getInvolvedLink     "beth am ymuno â ni!">
+<!ENTITY helpus.end                 "">
+
+<!ENTITY releaseNotes.link          "Nodiadau ryddhau">
+
+<!-- LOCALIZATION NOTE (bottomLinks.license): This is a link title that links to about:license. -->
+<!ENTITY bottomLinks.license        "Manylion Trwyddedu">
+
+<!-- LOCALIZATION NOTE (bottomLinks.rights): This is a link title that links to about:rights. -->
+<!ENTITY bottomLinks.rights         "Hawliau'r Defnyddiwr">
+
+<!-- LOCALIZATION NOTE (bottomLinks.privacy): This is a link title that links to https://www.mozilla.org/legal/privacy/. -->
+<!ENTITY bottomLinks.privacy        "Polisi Preifatrwydd">
+
+<!-- LOCALIZATION NOTE (update.checkingForUpdates): try to make the localized text short (see bug 596813 for screenshots). -->
+<!ENTITY update.checkingForUpdates  "Gwirio am ddiweddariadau…">
+<!-- LOCALIZATION NOTE (update.noUpdatesFound): try to make the localized text short (see bug 596813 for screenshots). -->
+<!ENTITY update.noUpdatesFound      "Mae &brandShortName; yn gyfredol">
+<!-- LOCALIZATION NOTE (update.adminDisabled): try to make the localized text short (see bug 596813 for screenshots). -->
+<!ENTITY update.adminDisabled       "Mae'r diweddariad wedi'i analluogi gan eich gweinyddwr">
+<!-- LOCALIZATION NOTE (update.otherInstanceHandlingUpdates): try to make the localized text short -->
+<!ENTITY update.otherInstanceHandlingUpdates "Mae &brandShortName; yn cael ei ddiweddaru gan enghraifft arall">
+
+<!-- LOCALIZATION NOTE (update.failed.start,update.failed.linkText,update.failed.end):
+     update.failed.start, update.failed.linkText, and update.failed.end all go into
+     one line with linkText being wrapped in an anchor that links to a site to download
+     the latest version of Firefox (e.g. https://www.firefox.com). As this is all in
+     one line, try to make the localized text short (see bug 596813 for screenshots). -->
+<!ENTITY update.failed.start        "Methodd y diweddaru. ">
+<!ENTITY update.failed.linkText     "Llwytho'r fersiwn diweddaraf i lawr">
+<!ENTITY update.failed.end          "">
+
+<!-- LOCALIZATION NOTE (update.manual.start,update.manual.end): update.manual.start and update.manual.end
+     all go into one line and have an anchor in between with text that is the same as the link to a site
+     to download the latest version of Firefox (e.g. https://www.firefox.com). As this is all in one line,
+     try to make the localized text short (see bug 596813 for screenshots). -->
+<!ENTITY update.manual.start        "Llwytho i lawr ">
+<!ENTITY update.manual.linkText     "y fersiwn diweddaraf">
+<!ENTITY update.manual.end          "">
+
+<!-- LOCALIZATION NOTE (update.unsupported.start,update.unsupported.linkText,update.unsupported.end):
+     update.unsupported.start, update.unsupported.linkText, and
+     update.unsupported.end all go into one line with linkText being wrapped in
+     an anchor that links to a site to provide additional information regarding
+     why the system is no longer supported. As this is all in one line, try to
+     make the localized text short (see bug 843497 for screenshots). -->
+<!ENTITY update.unsupported.start    "Nid oes modd i chi ddiweddaru'r system hwn ymhellach. ">
+<!ENTITY update.unsupported.linkText "Dysgu rhagor">
+<!ENTITY update.unsupported.end      "">
+
+<!-- LOCALIZATION NOTE (update.downloading.start,update.downloading.end): update.downloading.start and
+     update.downloading.end all go into one line, with the amount downloaded inserted in between. As this
+     is all in one line, try to make the localized text short (see bug 596813 for screenshots). The — is
+     the "em dash" (long dash).
+     example: Downloading update — 111 KB of 13 MB -->
+<!ENTITY update.downloading.start   "Llwytho'r diweddariad i lawr - ">
+<!ENTITY update.downloading.end     "">
+
+<!ENTITY update.applying            "Gosod y diweddariad…">
+<!ENTITY update.restarting          "Ailgychwyn…">
+
+<!-- LOCALIZATION NOTE (channel.description.start,channel.description.end): channel.description.start and
+     channel.description.end create one sentence, with the current channel label inserted in between.
+     example: You are currently on the _Stable_ update channel. -->
+<!ENTITY channel.description.start  "Rydych ar sianel diweddaru ">
+<!ENTITY channel.description.end    ".">
+
+<!ENTITY cmdCloseMac.commandKey "w">
diff --git a/l10n-cy/mail/chrome/messenger/aboutDownloads.dtd b/l10n-cy/mail/chrome/messenger/aboutDownloads.dtd
new file mode 100644
index 0000000000..73db5efd89
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/aboutDownloads.dtd
@@ -0,0 +1,23 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY aboutDownloads.title                      "Ffeiliau wedi'u Cadw">
+<!-- LOCALIZATION NOTE (cmd.show.label, cmd.show.accesskey, cmd.showMac.label,
+     cmd.showMac.accesskey):
+     The show and showMac commands are never shown together, thus they can share
+     the same access key (though the two access keys can also be different).
+     -->
+<!ENTITY cmd.show.label                            "Agor y Ffolder sy'n eu Cynnwys">
+<!ENTITY cmd.show.accesskey                        "F">
+<!ENTITY cmd.showMac.label                         "Dangos yn Finder">
+<!ENTITY cmd.showMac.accesskey                     "F">
+<!ENTITY cmd.open.label                            "Agor">
+<!ENTITY cmd.open.accesskey                        "o">
+<!ENTITY cmd.removeFromHistory.label               "Tynnu o'r Hanes">
+<!ENTITY cmd.removeFromHistory.accesskey           "T">
+<!ENTITY cmd.clearList.label                       "Clirio'r Rhestr">
+<!ENTITY cmd.clearList.accesskey                   "l">
+<!ENTITY cmd.clearList.tooltip                     "Tynnu pob cofnod o'r rhestr ffeiliau wedi eu cadw, ar wahân i lwythi i lawr sy'n digwydd ar hyn o bryd.">
+<!ENTITY cmd.searchDownloads.label                 "Chwilio…">
+<!ENTITY cmd.searchDownloads.key                   "w">
diff --git a/l10n-cy/mail/chrome/messenger/aboutRights.properties b/l10n-cy/mail/chrome/messenger/aboutRights.properties
new file mode 100644
index 0000000000..2a9f1b93dd
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/aboutRights.properties
@@ -0,0 +1,6 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+buttonLabel=Gwybod eich hawliau…
+buttonAccessKey=G
diff --git a/l10n-cy/mail/chrome/messenger/aboutSupportMail.properties b/l10n-cy/mail/chrome/messenger/aboutSupportMail.properties
new file mode 100644
index 0000000000..ad47fddc4c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/aboutSupportMail.properties
@@ -0,0 +1,15 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (warningLabel): Label for warning text that shows up when private data is included
+warningLabel=RHYBUDD:
+# LOCALIZATION NOTE (warningText): Warning text that shows up when private data is included
+warningText=Mae hwn yn cynnwys gwybodaeth sensitif na ddylai gael ei anfon ymlaen na'i gyhoeddi heb ganiatâd.
+
+# LOCALIZATION NOTE (fsType.local): Indicator that the displayed directory is on a local drive
+fsType.local = (Gyrrwr lleol)
+# LOCALIZATION NOTE (fsType.network): Indicator that the displayed directory is on the network
+fsType.network = (Gyrrwr rhwydwaith)
+# LOCALIZATION NOTE (fsType.unknown): Indicator that we couldn't figure out whether the directory is local or on a network
+fsType.unknown = (Lleoliad anhysbys)
diff --git a/l10n-cy/mail/chrome/messenger/accountCreationModel.properties b/l10n-cy/mail/chrome/messenger/accountCreationModel.properties
new file mode 100644
index 0000000000..3ac780124a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/accountCreationModel.properties
@@ -0,0 +1,21 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# This file has the strings, mostly error strings, for the logic / JS backend / model
+# files: fetchConfig.js, readFromXML.js, guessConfig.js, verifyConfig.js, createInBackend.js
+
+
+# readFromXML.js
+no_emailProvider.error=Nid yw'r ffeil ffurfweddu XML yn cynnwys ffurfweddiad cyfrif e-bost.
+outgoing_not_smtp.error=Rhaid i'r gweinydd anfon fod o fath SMTP
+
+# verifyConfig.js
+cannot_login.error=Methu mewngofnodi i'r gweinydd. Ffurfweddiad, enw defnyddiwr neu gyfrinair anghywir, siŵr o fod.
+
+
+# guessConfig.js
+cannot_find_server.error=Methu canfod gweinydd
+
+# exchangeAutoDiscover.js
+no_autodiscover.error=Mae'r Exchangen AutoDiscover XML yn annilys.
diff --git a/l10n-cy/mail/chrome/messenger/accountCreationUtil.properties b/l10n-cy/mail/chrome/messenger/accountCreationUtil.properties
new file mode 100644
index 0000000000..46728d91bd
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/accountCreationUtil.properties
@@ -0,0 +1,34 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# This file has the strings, mostly error strings, for the logic / JS backend / model
+# files: sanitizeDatatypes.js, fetchhttp.js, util.js
+
+
+# sanitizeDatatypes.js
+hostname_syntax.error=Mae'r enw gweinydd yn wag neu yn cynnwys nodau anghymeradwy. Dim ond llythrennau, rhifau, - a . sy'n cael eu caniatáu.
+alphanumdash.error=Mae'r llinyn yn cynnwys nodau anghymeradwy. Dim ond llythrennau, rhifau, - a . sy'n cael eu caniatáu.
+allowed_value.error=Nid yw'r gwerth hwn yn gymeradwy
+url_scheme.error=Nid oes caniatâd i'r cynllun URL
+url_parsing.error=Heb adnabod yr URL
+string_empty.error=Rhaid darparu gwerth ar gyfer y llinyn
+boolean.error=Nid booleanaidd
+no_number.error=Nid rhif
+number_too_large.error=Rhif yn rhy fawr
+number_too_small.error=Rhif yn rhy fach
+
+
+# fetchhttp.js
+cannot_contact_server.error=Methu cysylltu â'r gweinydd
+bad_response_content.error=Cynnwys ymateb gwael
+
+# verifyConfig.js
+# LOCALIZATION NOTE(auth_failed_generic.error): The login failed (server refused to allow the user in), but the server did not give any meaningful error message. This is a common case when the user entered a wrong password or is otherwise not allowed.
+auth_failed_generic.error=Methodd y mewngofnodi. A yw'r enw defnyddiwr/cyfeiriad e-bost a chyfrinair yn gywir?
+# LOCALIZATION NOTE(auth_failed_with_reason.error): The login failed (server refused to allow the user in), and the server gave an error message which we can present to the user. This is a common case when the user entered a wrong password or is otherwise not allowed. %1$S will be the IMAP/POP3/SMTP server hostname. %2$S will be the error message from the server (usually in the local language where the server is or in English).
+auth_failed_with_reason.error=Methodd y mewngofnodi. Dywedodd gweinydd %1$S: %2$S
+# LOCALIZATION NOTE(verification_failed.error): We had some other error, not during authentication with the server, but at earlier points, e.g. locally or we entirely failed to contact the given server, and we unfortunately have no detailed error message.
+verification_failed.error=Methiant dilysu mewngofnodi am reswm anhysbys.
+# LOCALIZATION NOTE(verification_failed_with_exception.error): We had some other error, not during authentication with the server, but at earlier points, e.g. locally or we entirely failed to contact the given server, and we have an error message. %1$S will be an error message, possibly in English
+verification_failed_with_exception.error=Methiant dilysu mewngofnodi gyda'r neges: %1$S
diff --git a/l10n-cy/mail/chrome/messenger/activity.dtd b/l10n-cy/mail/chrome/messenger/activity.dtd
new file mode 100644
index 0000000000..cdf84fd424
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/activity.dtd
@@ -0,0 +1,19 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- LOCALIZATION NOTE (window.width2, window.height): These values should be
+close to the golden ratio (1.618:1) while making sure it's wide enough for long
+file names and tall enough to hint that there are more activities in the list -->
+
+<!ENTITY window.width2                    "485">
+<!ENTITY window.height                    "300">
+
+<!ENTITY activity.title                  "Rheolwr Gweithgaredd">
+
+<!ENTITY cmd.close.commandkey             "w">
+<!ENTITY cmd.close2.commandkey            "j">
+<!ENTITY cmd.close2Unix.commandkey        "y">
+<!ENTITY cmd.clearList.label              "Clirio'r Rhestr">
+<!ENTITY cmd.clearList.tooltip            "Tynnu eitemau wedi'u cwblhau, diddymu a methu o'r rhestr">
+<!ENTITY cmd.clearList.accesskey          "C">
+
diff --git a/l10n-cy/mail/chrome/messenger/activity.properties b/l10n-cy/mail/chrome/messenger/activity.properties
new file mode 100644
index 0000000000..7a4cd2eedc
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/activity.properties
@@ -0,0 +1,99 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Status Text
+paused2=Oedwyd
+processing=Prosesu
+notStarted=Heb Gychwyn
+failed=Methwyd
+waitingForInput=Aros am fewnbwn
+waitingForRetry=Aros i geisio eto
+completed=Cwblhawyd
+canceled=Diddymwyd
+
+# LOCALIZATION NOTE (sendingMessages): this is used as a title for grouping processes in the activity manager when sending email.
+sendingMessages=Anfon Negeseuon
+sendingMessage=Anfon Neges
+# LOCALIZATION NOTE (sendingMessageWithSubject): %S will be replaced by the subject of the message being sent.
+sendingMessageWithSubject=Anfon Neges: %S
+copyMessage=Copïo neges i'r ffolder anfonwyd
+sentMessage=Neges Anfonwyd
+# LOCALIZATION NOTE (sentMessageWithSubject): %S will be replaced by the subject of the message being sent.
+sentMessageWithSubject=Neges Anfonwyd: %S
+failedToSendMessage=Methwyd anfon neges
+failedToCopyMessage=Methwyd copïo neges
+# LOCALIZATION NOTE (failedToSendMessageWithSubject): %S will be replaced by the subject of the message being sent.
+failedToSendMessageWithSubject=Methwyd anfon neges: %S
+# LOCALIZATION NOTE (failedToCopyMessageWithSubject): %S will be replaced by the subject of the message being sent.
+failedToCopyMessageWithSubject=Methwyd copïo neges: %S
+
+# LOCALIZATION NOTE (autosyncProcessProgress2): Do not translate the words "%1$S", "%2$S", "%3$S" and "%4$S" below.
+# Place the word %1$S in your translation where the number of the message being downloaded should appear.
+# Place the word %2$S in your translation where the total number of messages to be downloaded should appear.
+# Place the word %3$S in your translation where the name of the folder being processed should appear.
+# Place the word %4$S in your translation where the name of account being processed should appear.
+# EXAMPLE: Ted's account: Downloading message 334 of 1008 in Inbox…
+autosyncProcessProgress2=%4$S: Llwytho %1$S neges i lawr o %2$S i %3$S…
+# LOCALIZATION NOTE (autosyncProcessDisplayText): %S will be replaced by the folder name
+autosyncProcessDisplayText=Diweddaru ffolder %S
+# LOCALIZATION NOTE (autosyncEventDisplayText): %S will be replaced by the account name
+autosyncEventDisplayText=Mae %S yn gyfredol
+# LOCALIZATION NOTE (autosyncEventStatusText): %S will be replaced by total number of downloaded messages
+autosyncEventStatusText=Cyfanswm y nifer o negeseuon wedi'u llwytho i lawr: %S
+autosyncEventStatusTextNoMsgs=Heb lwytho negeseuon i lawr
+# LOCALIZATION NOTE (autosyncContextDisplayText): %S will be replaced by the account name
+autosyncContextDisplayText=Cydweddu: %S
+
+# LOCALIZATION NOTE (pop3EventStartDisplayText2): Do not translate the words "%1$S" and "%2$S" below.
+# Place the word %1$S in your translation where the name of the account being checked for new messages should appear.
+# Place the word %2$S in your translation where the name of the folder being checked for new messages should appear.
+# EXAMPLE: George's account: Checking Inbox for new messages…
+pop3EventStartDisplayText2=%1$S: Gwirio %2$S am negeseuon newydd…
+# LOCALIZATION NOTE (pop3EventDisplayText): %S will be replaced by the account name
+pop3EventDisplayText=Mae %S yn gyfredol
+# LOCALIZATION NOTE (pop3EventStatusText): #1 will be replaced by total number of downloaded messages
+pop3EventStatusText=#1 neges wedi'i lwytho i lawr;#1 neges wedi'u llwytho i lawr;
+pop3EventStatusTextNoMsgs=Dim negeseuon i'w llwytho i lawr
+
+# Message actions that show up in activity manager
+# LOCALIZATION NOTE (deletedMessages2): #1 number of messages, #2 folder name
+deletedMessages2=Dilëwyd #1 neges o #2;Dilëwyd #1 neges o #2
+# LOCALIZATION NOTE (movedMessages): #1 number of messages, #2 and #3: folder names
+movedMessages=Symudwyd #1 neges o #2 i #3;Symudwyd #1 neges o #2 i #3
+# LOCALIZATION NOTE (copiedMessages): #1 number of messages, #2 and #3: folder names
+copiedMessages=Copïwyd #1 neges o #2 i #3;Copïwyd #1 neges o #2 i #3
+# LOCALIZATION NOTE (fromServerToServer): #1 source server, #2 destination server
+fromServerToServer=0 #1 i #2
+# LOCALIZATION NOTE (deletedFolder): #1 folder name
+deletedFolder=Dilëwyd ffolder #1
+emptiedTrash=Sbwriel wedi'i Wagio
+# LOCALIZATION NOTE (movedFolder): #1 and #2 are folder names
+movedFolder=Syymudwyd ffolder #1 i #2
+# LOCALIZATION NOTE (movedFolderToTrash): #1 is the folder name
+movedFolderToTrash=Symudwyd ffolder #1 i'r Sbwriel
+# LOCALIZATION NOTE (copiedFolder): #1 and #2 are folder names
+copiedFolder=Copïwyd ffolder #1 i ffolder #2
+# LOCALIZATION NOTE (renamedFolder): #1 and #2 are folder names
+renamedFolder=Ailenwi ffolder #1 i #2
+indexing=Mynegeio negeseuon
+# LOCALIZATION NOTE (indexingFolder): #1 is a folder name
+indexingFolder=Mynegeio negeseuon yn #1
+indexingStatusVague=Pennu pa negeseuon i'w mynegeio
+# LOCALIZATION NOTE (indexingFolderStatusVague): #1 is a folder name
+indexingFolderStatusVague=Pennu pa negeseuon i'w mynegeio yn #1
+# LOCALIZATION NOTE (indexingStatusExact):
+#   #1 is the number of the message currently being indexed
+#   #2 is the total number of messages being indexed
+#   #3 is the percentage of indexing that is complete
+indexingStatusExact=Mynegeio #1 o #2 neges;Mynegeio #1 o #2 neges (wedi cwblhau #3%)
+# LOCALIZATION NOTE (indexingFolderStatusExact):
+#   #1 is the number of the message currently being indexed
+#   #2 is the total number of messages being indexed
+#   #3 is the percentage of indexing that is complete
+#   #4 is a folder name
+indexingFolderStatusExact=Mynegeio #1 o #2 neges yn #4;Mynegeio #1 o #2 neges yn #4; (wedi cwblhau #3%)
+# LOCALIZATION NOTE (indexedFolder): #1 number of messages; #2 folder name
+indexedFolder=Mynegewyd #1 neges yn #2;Mynegewyd #1 neges yn #2
+# LOCALIZATION NOTE (indexedFolderStatus): #1 number of seconds spent indexing
+indexedFolderStatus=#1 eiliad wedi mynd heibio;#1 eiliad wedi mynd heibio
diff --git a/l10n-cy/mail/chrome/messenger/addbuddy.dtd b/l10n-cy/mail/chrome/messenger/addbuddy.dtd
new file mode 100644
index 0000000000..bafd30d80c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addbuddy.dtd
@@ -0,0 +1,7 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY addBuddyWindow.title           "Ychwanegu cysylltiad">
+<!ENTITY name.label                     "Enw Defnyddiwr">
+<!ENTITY account.label                  "Cyfrif">
diff --git a/l10n-cy/mail/chrome/messenger/addons.properties b/l10n-cy/mail/chrome/messenger/addons.properties
new file mode 100644
index 0000000000..ab88e9607d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addons.properties
@@ -0,0 +1,256 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+xpinstallPromptMessage=Rhwystrodd %S y wefan rhag gofyn i chi osod meddalwedd ar eich cyfrifiadur.
+# LOCALIZATION NOTE (xpinstallPromptMessage.header)
+# The string contains the hostname of the site the add-on is being installed from.
+xpinstallPromptMessage.header=Caniatáu i %S osod ategyn?
+xpinstallPromptMessage.message=Rydych yn ceisio gosod ychwanegyn o %S. Gwnewch yn siŵr eich bod yn ymddiried yn y wefan hon cyn parhau.
+xpinstallPromptMessage.header.unknown=Caniatáu i wefan anhysbys osod ategyn?
+xpinstallPromptMessage.message.unknown=Rydych yn ceisio gosod ychwanegyn o wefan anhysbys. Gwnewch yn siŵr eich bod yn ymddiried yn y wefan hon cyn parhau.
+xpinstallPromptMessage.learnMore=Dysgwch ragor am osod ategion yn ddiogel
+xpinstallPromptMessage.dontAllow=Peidio â Chaniatáu
+xpinstallPromptMessage.dontAllow.accesskey=P
+xpinstallPromptMessage.neverAllow=Byth Caniatáu
+xpinstallPromptMessage.neverAllow.accesskey=B
+# Accessibility Note:
+# Be sure you do not choose an accesskey that is used elsewhere in the active context (e.g. main menu bar, submenu of the warning popup button)
+# See https://website-archive.mozilla.org/www.mozilla.org/access/access/keyboard/ for details
+xpinstallPromptMessage.install=Ymlaen i'r Gosod
+xpinstallPromptMessage.install.accesskey=Y
+
+# Accessibility Note:
+# Be sure you do not choose an accesskey that is used elsewhere in the active context (e.g. main menu bar, submenu of the warning popup button)
+# See http://www.mozilla.org/access/keyboard/accesskey for details
+xpinstallDisabledMessageLocked=Mae gosod meddalwedd wedi ei analluogi gan eich gweinyddwr system.
+xpinstallDisabledMessage=Mae gosod meddalwedd wedi ei analluogi. Cliciwch Galluogi a cheisio eto.
+xpinstallDisabledButton=Galluogi
+xpinstallDisabledButton.accesskey=G
+
+# LOCALIZATION NOTE (addonInstallBlockedByPolicy)
+# This message is shown when the installation of an add-on is blocked by
+# enterprise policy. %1$S is replaced by the name of the add-on.
+# %2$S is replaced by the ID of add-on. %3$S is a custom message that
+# the administration can add to the message.
+addonInstallBlockedByPolicy=Mae %1$S (%2$S) wedi ei rwystro gan eich gweinyddwr system.%3$S
+# LOCALIZATION NOTE (addonDomainBlockedByPolicy)
+# This message is shown when the installation of add-ons from a domain
+# is blocked by enterprise policy.
+addonDomainBlockedByPolicy=Rhwystrodd eich gweinyddwr systemau y wefan hon rhag gofyn i chi osod meddalwedd ar eich cyfrifiadur.
+
+# LOCALIZATION NOTE (addonPostInstall.message2)
+# %S is replaced with the localized named of the extension that was
+# just installed.
+addonPostInstall.message2=Ychwanegwyd %S
+
+# LOCALIZATION NOTE (addonDownloadingAndVerifying):
+# Semicolon-separated list of plural forms. See:
+# http://developer.mozilla.org/en/docs/Localization_and_Plurals
+# Also see https://bugzilla.mozilla.org/show_bug.cgi?id=570012 for mockups
+addonDownloadingAndVerifying=Llwytho i lawr a dilysu #1 ychwanegion…;Llwytho i lawr a dilysu #1 ychwanegyn…;Llwytho i lawr a dilysu #1 ychwanegyn…;Llwytho i lawr a dilysu #1 ychwanegyn…;Llwytho i lawr a dilysu #1 ychwanegyn…;Llwytho i lawr a dilysu #1 ychwanegyn…
+addonDownloadVerifying=Dilysu
+
+addonInstall.unsigned=(Heb eu gwirio)
+addonInstall.cancelButton.label=Diddymu
+addonInstall.cancelButton.accesskey=D
+addonInstall.acceptButton2.label=Ychwanegu
+addonInstall.acceptButton2.accesskey=Y
+
+# LOCALIZATION NOTE (addonConfirmInstallMessage,addonConfirmInstallUnsigned):
+# Semicolon-separated list of plural forms. See:
+# http://developer.mozilla.org/en/docs/Localization_and_Plurals
+# #1 is brandShortName
+# #2 is the number of add-ons being installed
+addonConfirmInstall.message=Hoffai'r wefan hon osod ychwanegyn yn #1:;Hoffai'r wefan hon osod #2 ychwanegyn yn #1:;Hoffai'r wefan hon osod #2 ychwanegyn yn #1:;Hoffai'r wefan hon osod #2 ychwanegyn yn #1:;Hoffai'r wefan hon osod #2 ychwanegyn yn #1:;Hoffai'r wefan hon osod #2 ychwanegyn yn #1:
+addonConfirmInstallUnsigned.message=Rhybudd: Hoffai&#39;r wefan hon osod ychwanegiad heb ei wirio yn # 1. Ewch yn eich perygl eich hun.; Rhybudd: Hoffai&#39;r wefan hon osod # 2 ychwanegiadau heb eu cadarnhau yn # 1. Ewch ymlaen ar eich pen eich hun.
+
+# LOCALIZATION NOTE (addonConfirmInstallSomeUnsigned.message):
+# Semicolon-separated list of plural forms. See:
+# http://developer.mozilla.org/en/docs/Localization_and_Plurals
+# #1 is brandShortName
+# #2 is the total number of add-ons being installed (at least 2)
+addonConfirmInstallSomeUnsigned.message=;Rhybudd: Hoffai'r wefan hon osod #2 ychwanegion yn #1, mae rhai ohonynt heb eu gwirio. Gwnewch hyn ar eich menter eich hun.;Rhybudd: Hoffai'r wefan hon osod #2 ychwanegyn yn #1, mae rhai ohonynt heb eu gwirio. Gwnewch hyn ar eich menter eich hun.;Rhybudd: Hoffai'r wefan hon osod #2 ychwanegyn yn #1, mae rhai ohonynt heb eu gwirio. Gwnewch hyn ar eich menter eich hun.;Rhybudd: Hoffai'r wefan hon osod #2 ychwanegyn yn #1, mae rhai ohonynt heb eu gwirio. Gwnewch hyn ar eich menter eich hun.;Rhybudd: Hoffai'r wefan hon osod #2 ychwanegyn yn #1, mae rhai ohonynt heb eu gwirio. Gwnewch hyn ar eich menter eich hun.
+
+# LOCALIZATION NOTE (addonInstalled):
+# %S is the name of the add-on
+addonInstalled=Mae %S wedi'i osod yn llwyddiannus.
+# LOCALIZATION NOTE (addonsGenericInstalled):
+# Semicolon-separated list of plural forms. See:
+# http://developer.mozilla.org/en/docs/Localization_and_Plurals
+# #1 number of add-ons
+addonsGenericInstalled=Nid oes ychwanegion wedi eu gosod.;Mae #1 ychwanegyn wedi ei osod yn llwyddiannus.;Mae #1 ychwanegyn wedi eu gosod yn llwyddiannus.;Mae #1 ychwanegyn wedi eu gosod yn llwyddiannus.;Mae #1 ychwanegyn wedi eu gosod yn llwyddiannus.;Mae #1 ychwanegyn wedi eu gosod yn llwyddiannus.
+
+# LOCALIZATION NOTE (addonInstallError-1, addonInstallError-2, addonInstallError-3, addonInstallError-4, addonInstallError-5, addonLocalInstallError-1, addonLocalInstallError-2, addonLocalInstallError-3, addonLocalInstallError-4, addonLocalInstallError-5):
+# %1$S is the application name, %2$S is the add-on name
+addonInstallError-1=Nid oedd modd llwytho'r ychwanegyn i lawr oherwydd methiant y cysylltiad.
+addonInstallError-2=Nid oedd modd gosod yr ychwanegyn am nad yw'n cydweddu â'r ychwanegyn roedd %1$S yn ei ddisgwyl.
+addonInstallError-3=Nid oedd modd llwytho'r ychwanegyn i lawr o'r wefan hon oherwydd ei fod yn ymddangos yn llwgr.
+addonInstallError-4=Nid oedd modd gosod %2$S gan nad oedd %1$S yn gallu newid y linell angenrheidiol.
+addonInstallError-5=Mae %1$S wedi atal y wefan rhag gosod ychwanegyn sydd heb ei wirio.
+addonLocalInstallError-1=Nid oedd modd gosod yr ychwanegyn oherwydd gwall system.
+addonLocalInstallError-2=Nid oedd modd gosod yr ychwanegyn am nad yw'n cydweddu â'r ychwanegyn %1$S disgwyliwyd.
+addonLocalInstallError-3=Nid oedd modd gosod yr ychwanegyn am ei fod yn edrych yn llwgr.
+addonLocalInstallError-4=Nid oedd modd gosod %2$S gan nad oedd %1$S yn gallu newid y linell angenrheidiol.
+addonLocalInstallError-5=Nid oedd modd gosod yr ychwanegyn am nad yw wedi ei wirio.
+
+# LOCALIZATION NOTE (addonInstallErrorIncompatible):
+# %1$S is the application name, %2$S is the application version, %3$S is the add-on name
+addonInstallErrorIncompatible=Nid oedd modd gosod %3$S am nad yw'n cydweddu â %1$S %2$S.
+
+# LOCALIZATION NOTE (addonInstallErrorBlocklisted): %S is add-on name
+addonInstallErrorBlocklisted=Nid oedd modd gosod %S am fod risg uchel iddo achosi problemau sefydlogrwydd a diogelwch.
+
+# LOCALIZATION NOTE (webextPerms.header,webextPerms.headerWithPerms,webextPerms.headerUnsigned,webextPerms.headerUnsignedWithPerms)
+# These strings are used as headers in the webextension permissions dialog,
+# %S is replaced with the localized name of the extension being installed.
+# See https://bug1308309.bmoattachments.org/attachment.cgi?id=8814612
+# for an example of the full dialog.
+# Note, these strings will be used as raw markup. Avoid characters like <, >, &
+webextPerms.header=Ychwanegu %S?
+
+# %S is brandShortName
+webextPerms.experimentWarning=Gall ychwanegion maleisus ddwyn eich manylion preifat neu gyfaddawdu eich cyfrifiadur. Gosodwch yr ychwanegiad hwn dim ond os ydych yn ymddiried yn y ffynhonnell.
+webextPerms.headerWithPerms=Ychwanegu %S? Bydd gan yr estyniad hwn ganiatâd i:
+webextPerms.headerUnsigned=Ychwanegu %S? Nid yw'r estyniad hwn wedi'i wirio. Gall estyniadau maleisus ddwyn eich manylion preifat neu gyfaddawdu eich cyfrifiadur. Ychwanegwch ef dim ond os ydych chi'n ymddiried yn y ffynhonnell.
+webextPerms.headerUnsignedWithPerms=Ychwanegu %S? Nid yw'r estyniad hwn wedi'i wirio. Gall estyniadau maleisus ddwyn eich manylion preifat neu gyfaddawdu eich cyfrifiadur. Ychwanegwch ef dim ond os ydych chi'n ymddiried yn y ffynhonnell. Bydd gan yr estyniad hwn ganiatâd i:
+webextPerms.learnMore2=Dysgu rhagor
+webextPerms.add.label=Ychwanegu
+webextPerms.add.accessKey=Y
+webextPerms.cancel.label=Diddymu
+webextPerms.cancel.accessKey=D
+
+# LOCALIZATION NOTE (webextPerms.sideloadMenuItem)
+# %1$S will be replaced with the localized name of the sideloaded add-on.
+# %2$S will be replace with the name of the application (e.g., Firefox, Nightly)
+webextPerms.sideloadMenuItem=%1$S wedi ei ychwanegu i %2$S
+
+# LOCALIZATION NOTE (webextPerms.sideloadHeader)
+# This string is used as a header in the webextension permissions dialog
+# when the extension is side-loaded.
+# %S is replaced with the localized name of the extension being installed.
+# Note, this string will be used as raw markup. Avoid characters like <, >, &
+webextPerms.sideloadHeader=%S wedi ei ychwanegu
+webextPerms.sideloadText2=Mae rhaglen arall ar eich cyfrifiadur wedi gosod ychwanegiad a allai effeithio ar eich porwr. Adolygwch geisiadau caniatâd yr ychwanegyn hwn a dewiswch Galluogi neu Diddymu (i'w adael yn anabl).
+webextPerms.sideloadTextNoPerms=Mae rhaglen arall ar eich cyfrifiadur wedi gosod ychwanegyn y gall effeithio ar eich porwr. Darllenwch geisiadau caniatâd yr ychwanegyn a dewis i Alluogi neu Ddiddymu (i'w adael wedi ei analluogi).
+
+webextPerms.sideloadEnable.label=Galluogi
+webextPerms.sideloadEnable.accessKey=G
+webextPerms.sideloadCancel.label=Diddymu
+webextPerms.sideloadCancel.accessKey=D
+
+# LOCALIZATION NOTE (webextPerms.updateMenuItem)
+# %S will be replaced with the localized name of the extension which
+# has been updated.
+webextPerms.updateMenuItem=Mae %S angen caniatâd newydd
+
+# LOCALIZATION NOTE (webextPerms.updateText2)
+# %S is replaced with the localized name of the updated extension.
+# Note, this string will be used as raw markup. Avoid characters like <, >, &
+webextPerms.updateText2=Mae %S wedi'i ddiweddaru. Rhaid i chi gymeradwyo caniatâd newydd cyn y bydd y fersiwn wedi'i ddiweddaru'n cael ei osod. Bydd dewis “Diddymu” yn cynnal eich fersiwn estyniad cyfredol. Bydd gan yr estyniad hwn ganiatâd i:
+
+webextPerms.updateAccept.label=Diweddaru
+webextPerms.updateAccept.accessKey=D
+
+# LOCALIZATION NOTE (webextPerms.optionalPermsHeader)
+# %S is replace with the localized name of the extension requested new
+# permissions.
+# Note, this string will be used as raw markup. Avoid characters like <, >, &
+webextPerms.optionalPermsHeader=Mae %S yn gofyn am ganiatâd ychwanegol.
+webextPerms.optionalPermsListIntro=Mae eisiau:
+webextPerms.optionalPermsAllow.label=Caniatáu
+webextPerms.optionalPermsAllow.accessKey=C
+webextPerms.optionalPermsDeny.label=Gwrthod
+webextPerms.optionalPermsDeny.accessKey=G
+
+webextPerms.description.accountsFolders=Creu, ailenwi neu ddileu ffolderi eich cyfrif e-bost
+webextPerms.description.accountsIdentities=Creu, newid neu ddileu ffolderi eich cyfrif e-bost
+webextPerms.description.accountsRead2=Gweld eich cyfrifon e-bost, eu hunaniaeth a'u ffolderi
+webextPerms.description.addressBooks=Darllenwch ac addasu eich llyfrau cyfeiriad a chysylltiadau
+webextPerms.description.bookmarks=Darllen a newid nodau tudalen
+webextPerms.description.browserSettings=Darllen a newid gosodiadau'r porwr
+webextPerms.description.browsingData=Clirio'r hanes pori diweddar, cwcis a data cysylltiedig
+webextPerms.description.clipboardRead=Estyn data o'r clipfwrdd
+webextPerms.description.clipboardWrite=Mewnbynnu data i'r clipfwrdd
+webextPerms.description.compose=Darllenwch ac addasu eich negeseuon e-bost wrth i chi eu cyfansoddi a'u hanfon
+webextPerms.description.compose.send=Anfon negeseuon e-bost wedi'u cyfansoddi ar eich rhan
+webextPerms.description.compose.save=Cadw negeseuon e-bost wedi'u hysgrifennu fel drafftiau neu dempledi
+webextPerms.description.declarativeNetRequest=Rhwystro cynnwys ar unrhyw dudalen
+webextPerms.description.devtools=Estyn offer datblygwyr i gael mynediad at eich data mewn tabiau agored
+webextPerms.description.dns=Manylion mynediad at IP ac enw gwesteiwr
+webextPerms.description.downloads=Llwytho i lawr, darllen ffeiliau a newid hanes llwytho i lawr y porwr
+webextPerms.description.downloads.open=Agor ffeiliau a llwythwyd i lawr i'ch cyfrifiadur
+# LOCALIZATION NOTE (webextPerms.description.experiment)
+# %S will be replaced with the name of the application
+webextPerms.description.experiment=Meddu ar fynediad llawn, heb gyfyngiad i %S, a'ch cyfrifiadur
+webextPerms.description.find=Darllen testun yr holl dabiau sydd ar agor
+webextPerms.description.geolocation=Mynediad i'ch lleoliad
+webextPerms.description.history=Mynediad at eich hanes pori
+webextPerms.description.management=Monitro'r defnydd o estyniadau a rheoli themâu
+webextPerms.description.messagesImport=Mewnforio negeseuon i Thunderbird
+webextPerms.description.messagesModify=Darllenwch ac addaswch eich negeseuon e-bost wrth iddyn nhw gael eu dangos i chi
+webextPerms.description.messagesMove2=Copïo neu symud eich negeseuon e-bost (gan gynnwys eu symud i'r ffolder sbwriel)
+webextPerms.description.messagesDelete=Dileu eich negeseuon e-bost yn barhaol
+webextPerms.description.messagesRead=Darllenwch eich negeseuon e-bost a'u marcio neu eu tagio
+webextPerms.description.messagesTags=Creu, addasu a dileu tagiau neges
+# LOCALIZATION NOTE (webextPerms.description.nativeMessaging)
+# %S will be replaced with the name of the application
+webextPerms.description.nativeMessaging=Cyfnewid negeseuon gyda rhaglenni ar wahân i %S
+webextPerms.description.notifications=Dangos hysbysiadau i chi
+webextPerms.description.pkcs11=Darparu gwasanaethau dilysiad cryptograffig
+webextPerms.description.privacy=Darllen a newid gosodiadau preifatrwydd
+webextPerms.description.proxy=Rheoli gosodiadau dirprwy'r porwr
+webextPerms.description.sessions=Mynediad at y tabiau caewyd yn ddiweddar
+webextPerms.description.tabs=Mynediad at dabiau'r porwyr
+webextPerms.description.tabHide=Cuddio a dangos tabiau'r porwr
+webextPerms.description.topSites=Mynediad at eich hanes pori
+webextPerms.description.unlimitedStorage=Cadw diddiwedd o swm data diddiwedd ochr y cleient
+webextPerms.description.webNavigation=Cael mynediad at weithgaredd wrth lywio
+
+webextPerms.hostDescription.allUrls=Cael mynediad at eich data ar gyfer pob gwefan
+
+# LOCALIZATION NOTE (webextPerms.hostDescription.wildcard)
+# %S will be replaced by the DNS domain for which a webextension
+# is requesting access (e.g., mozilla.org)
+webextPerms.hostDescription.wildcard=Cael mynediad at eich data ym mhob gwefan ym mharth %S
+
+# LOCALIZATION NOTE (webextPerms.hostDescription.tooManyWildcards):
+# Semi-colon list of plural forms.
+# See: http://developer.mozilla.org/en/docs/Localization_and_Plurals
+# #1 will be replaced by an integer indicating the number of additional
+# domains for which this webextension is requesting permission.
+webextPerms.hostDescription.tooManyWildcards=Peidio cael mynediad i'ch data mewn parthau eraill;Cael mynediad at eich data mewn #1 parth arall;Cael mynediad at eich data mewn #1 barth arall;Cael mynediad at eich data mewn #1 parth arall;Cael mynediad at eich data mewn #1 parth arall;Cael mynediad at eich data mewn #1 parth arall
+
+# LOCALIZATION NOTE (webextPerms.hostDescription.oneSite)
+# %S will be replaced by the DNS host name for which a webextension
+# is requesting access (e.g., www.mozilla.org)
+webextPerms.hostDescription.oneSite=Cael mynediad at eich data yn %S
+
+# LOCALIZATION NOTE (webextPerms.hostDescription.tooManySites)
+# Semi-colon list of plural forms.
+# See: http://developer.mozilla.org/en/docs/Localization_and_Plurals
+# #1 will be replaced by an integer indicating the number of additional
+# hosts for which this webextension is requesting permission.
+webextPerms.hostDescription.tooManySites=Peidio cael mynediad i'ch data mewn gwefannau eraill;Cael mynediad at eich data mewn #1 gwefan arall;Cael mynediad at eich data mewn #1 wefan arall;Cael mynediad at eich data mewn #1 gwefan arall;Cael mynediad at eich data mewn #1 gwefan arall;Cael mynediad at eich data mewn #1 gwefan arall
+
+# LOCALIZATION NOTE (webextSitePerms.headerWithPerms,webextSitePerms.headerUnsignedWithPerms)
+# This string is used as a header in the webextension permissions dialog,
+# %1$S is replaced with the localized name of the extension being installed.
+# %2$S will be replaced by the DNS host name for which a webextension enables permissions
+# Note, this string will be used as raw markup. Avoid characters like <, >, &
+webextSitePerms.headerWithPerms=Ychwanegu %1$S? Mae'r estyniad hwn yn rhoi'r galluoedd canlynol i %2$S:
+webextSitePerms.headerUnsignedWithPerms=Ychwanegu %1$S? Nid yw'r estyniad hwn wedi'i wirio. Gall estyniadau maleisus ddwyn eich manylion preifat neu gyfaddawdu eich cyfrifiadur. Ychwanegwch ef dim ond os ydych chi'n ymddiried yn y ffynhonnell. Mae'r estyniad hwn yn rhoi'r galluoedd canlynol i %2$S:
+
+# These should remain in sync with permissions.NAME.label in sitePermissions.properties
+webextSitePerms.description.midi=Mynediad at ddyfeisiau MIDI
+webextSitePerms.description.midi-sysex=Mynediad at ddyfeisiau MIDI sydd â chefnogaeth SysEx
+
+# LOCALIZATION NOTE (webext.defaultSearch.description)
+# %1$S is replaced with the localized named of the extension that is asking to change the default search engine.
+# %2$S is replaced with the name of the current search engine
+# %3$S is replaced with the name of the new search engine
+webext.defaultSearch.description=Mae %1$S eisiau newid eich peiriant chwilio rhagosodedig o %2$S i %3$S. Ydy hynny'n iawn?
+webext.defaultSearchYes.label=Iawn
+webext.defaultSearchYes.accessKey=I
+webext.defaultSearchNo.label=Na
+webext.defaultSearchNo.accessKey=N
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/abAddressBookNameDialog.dtd b/l10n-cy/mail/chrome/messenger/addressbook/abAddressBookNameDialog.dtd
new file mode 100644
index 0000000000..917b01a884
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/abAddressBookNameDialog.dtd
@@ -0,0 +1,7 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Labels -->
+
+<!ENTITY name.label      "Enw Llyfr Cyfeiriadau:">
+<!ENTITY name.accesskey  "L">
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/abContactsPanel.dtd b/l10n-cy/mail/chrome/messenger/addressbook/abContactsPanel.dtd
new file mode 100644
index 0000000000..1117163995
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/abContactsPanel.dtd
@@ -0,0 +1,49 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY propertiesMenu.label               "Priodweddau">
+<!ENTITY propertiesMenu.accesskey           "P">
+<!ENTITY propertiesCmd.key                  "i">
+<!ENTITY abPropertiesMenu.label             "Priodweddau Llyfr Cyfeiriadau">
+<!ENTITY abPropertiesMenu.accesskey         "P">
+<!ENTITY contactPropertiesMenu.label        "Priodweddau Cyswllt">
+<!ENTITY contactPropertiesMenu.accesskey    "r">
+<!ENTITY mailingListPropertiesMenu.label    "Priodweddau Rhestr E-bostio">
+<!ENTITY mailingListPropertiesMenu.accesskey "o">
+
+<!ENTITY abContextMenuButton.tooltip        "Dangos Cyd-destun Dewislen y Llyfr Cyfeiriadau">
+<!ENTITY addressbookPicker.label            "Llyfr Cyfeiriadau:">
+<!ENTITY addressbookPicker.accesskey        "L">
+<!ENTITY searchContacts.label               "Chwilio drwy'r Cysylltiadau:">
+<!ENTITY searchContacts.accesskey           "d">
+<!ENTITY SearchNameOrEmail.label            "Enw neu E-bost">
+
+<!ENTITY addtoToFieldMenu.label             "Ychwanegu i'r maes">
+<!ENTITY addtoToFieldMenu.accesskey         "m">
+<!ENTITY addtoCcFieldMenu.label             "Ychwanegu i faes Cc">
+<!ENTITY addtoCcFieldMenu.accesskey         "C">
+<!ENTITY addtoBccFieldMenu.label            "Ychwanegu i faed Bcc">
+<!ENTITY addtoBccFieldMenu.accesskey        "B">
+<!ENTITY deleteAddrBookCard.label           "Dileu">
+<!ENTITY deleteAddrBookCard.accesskey       "D">
+<!ENTITY propertiesContext.label            "Priodweddau">
+<!ENTITY propertiesContext.accesskey        "P">
+<!ENTITY abPropertiesContext.label          "Priodweddau">
+<!ENTITY abPropertiesContext.accesskey      "P">
+<!ENTITY editContactContext.label           "Golygu Cysylltiad">
+<!ENTITY editContactContext.accesskey       "G">
+<!ENTITY editMailingListContext.label       "Golygu Rhestr">
+<!ENTITY editMailingListContext.accesskey   "G">
+
+<!ENTITY newContactAbContext.label          "Cysylltiad Newydd">
+<!ENTITY newContactAbContext.accesskey      "C">
+<!ENTITY newListAbContext.label             "Rhestr Newydd">
+<!ENTITY newListAbContext.accesskey         "R">
+
+<!ENTITY toButton.label                     "Ychwanegu at:">
+<!ENTITY toButton.accesskey                 "a">
+<!ENTITY ccButton.label                     "Ychwanegu at Cc:">
+<!ENTITY ccButton.accesskey                 "C">
+<!ENTITY bccButton.label                    "Ychwanegu at Bcc:">
+<!ENTITY bccButton.accesskey                "B">
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/abMailListDialog.dtd b/l10n-cy/mail/chrome/messenger/addressbook/abMailListDialog.dtd
new file mode 100644
index 0000000000..71a6610451
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/abMailListDialog.dtd
@@ -0,0 +1,22 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Title -->
+
+<!ENTITY mailListWindowAdd.title        "Rhestr E-bostio Newydd">
+<!-- Labels and Access Keys -->
+
+<!ENTITY addToAddressBook.label         "Ychwanegu at: ">
+<!ENTITY addToAddressBook.accesskey     "Y">
+<!ENTITY ListName.label                 "Enw'r Rhestr: ">
+<!ENTITY ListName.accesskey             "R">
+<!ENTITY ListNickName.label             "Llys Enw'r Rhestr: ">
+<!ENTITY ListNickName.accesskey         "L">
+<!ENTITY ListDescription.label          "Disgrifiad: ">
+<!ENTITY ListDescription.accesskey      "D">
+<!-- See bug 58485, when we implement drag and drop, add 'or drag addresses' back in -->
+<!ENTITY AddressTitle.label             "Teipiwch gyfeiriadau e-bost i'w hychwanegu at y rhestr e-bostio:">
+<!ENTITY AddressTitle.accesskey         "e">
+<!ENTITY UpButton.label                 "Symud i Fyny">
+<!ENTITY DownButton.label               "Symud i Lawr">
+
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/abMainWindow.dtd b/l10n-cy/mail/chrome/messenger/addressbook/abMainWindow.dtd
new file mode 100644
index 0000000000..09a89e3c59
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/abMainWindow.dtd
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY showAsDefault.label                            "Cyfarwyddiadur cychwyn rhagosodedig">
+<!ENTITY showAsDefault.accesskey                        "c">
+
+<!-- Search Bar -->
+<!ENTITY SearchNameOrEmail.label                        "Enw neu E-bost">
+
+<!-- Results Pane -->
+<!ENTITY Addrbook.label                                 "Llyfr Cyfeiriadau">
+<!ENTITY GeneratedName.label                            "Enw">
+<!ENTITY PrimaryEmail.label                             "E-bost">
+
+<!-- Card Summary Pane -->
+
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/abResultsPane.dtd b/l10n-cy/mail/chrome/messenger/addressbook/abResultsPane.dtd
new file mode 100644
index 0000000000..6b5c4b4e9d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/abResultsPane.dtd
@@ -0,0 +1,38 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY Addrbook.label                        "Llyfr Cyfeiriadau">
+<!ENTITY Addrbook.accesskey                    "C">
+<!ENTITY GeneratedName.label                   "Enw">
+<!ENTITY GeneratedName.accesskey               "E">
+<!ENTITY PrimaryEmail.label                    "E-bost">
+<!ENTITY PrimaryEmail.accesskey                "b">
+<!ENTITY Company.label                         "Corff">
+<!ENTITY Company.accesskey                     "o">
+<!ENTITY _PhoneticName.label                   "Enw Seinegol">
+<!ENTITY _PhoneticName.accesskey               "o">
+<!ENTITY NickName.label                        "Llysenw">
+<!ENTITY NickName.accesskey                    "l">
+<!ENTITY SecondEmail.label                     "E-bost Ychwanegol">
+<!ENTITY SecondEmail.accesskey                 "b">
+<!ENTITY Department.label                      "Adran">
+<!ENTITY Department.accesskey                  "r">
+<!ENTITY JobTitle.label                        "Teitl">
+<!ENTITY JobTitle.accesskey                    "T">
+<!ENTITY CellularNumber.label                  "Symudol">
+<!ENTITY CellularNumber.accesskey              "S">
+<!ENTITY PagerNumber.label                     "Swnyn">
+<!ENTITY PagerNumber.accesskey                 "w">
+<!ENTITY FaxNumber.label                       "Ffacs">
+<!ENTITY FaxNumber.accesskey                   "F">
+<!ENTITY HomePhone.label                       "Ffôn Cartref">
+<!ENTITY HomePhone.accesskey                   "F">
+<!ENTITY WorkPhone.label                       "Ffôn Gwaith">
+<!ENTITY WorkPhone.accesskey                   "G">
+<!ENTITY ChatName.label                        "Enw Sgwrsio">
+<!ENTITY ChatName.accesskey                    "S">
+<!ENTITY sortAscending.label                   "Esgyn">
+<!ENTITY sortAscending.accesskey               "E">
+<!ENTITY sortDescending.label                  "Disgyn">
+<!ENTITY sortDescending.accesskey              "D">
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/addressBook.properties b/l10n-cy/mail/chrome/messenger/addressbook/addressBook.properties
new file mode 100644
index 0000000000..e18efbd61b
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/addressBook.properties
@@ -0,0 +1,178 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The following are used by the Mailing list dialog.
+# LOCALIZATION NOTE (mailingListTitleEdit): %S will be replaced by the Mailing List's display name.
+mailingListTitleEdit=Golygu %S
+emptyListName=Rhaid cyflwyno enw rhestr.
+badListNameCharacters=Nid yw enw rhestr yn gallu cynnwys unrhyw un o'r nodau canlynol: < > ; , "
+badListNameSpaces=Nid yw enw rhestr yn gallu cynnwys nifer o fylchau cyfagos.
+lastFirstFormat=%S, %S
+firstLastFormat=%S, %S
+
+allAddressBooks=Pob Llyfr Cyfeiriadau
+
+newContactTitle=Cysylltiad Newydd
+# %S will be the contact's display name
+newContactTitleWithDisplayName=Cysylltiad newydd %S
+editContactTitle=Golygu Cysylltiad
+# %S will be the contact's display name
+editContactTitleWithDisplayName=Golygu Cysylltiad %S
+# don't translate vCard
+editVCardTitle=Golygu vCard
+# %S will be the card's display name, don't translate vCard
+editVCardTitleWithDisplayName=Golygu vCard %S
+
+## LOCALIZATION NOTE (cardRequiredDataMissingMessage):  do not localize \n
+cardRequiredDataMissingMessage=Rhaid rhoi o leiaf un o'r eitemau canlynol:\nCyfeiriad e-bost, Enw Cyntaf, Enw Olaf, Enw Dangos, Corff.
+cardRequiredDataMissingTitle=Mae Gwybodaeth Angenrheidiol ar Goll
+incorrectEmailAddressFormatMessage=Rhaid i'r prif gyfeiriad fod ar ffurf defnyddiwr@gwesteiwr.
+incorrectEmailAddressFormatTitle=Fformat Cyfeiriad Anghywir
+
+viewListTitle=Rhestr E-bostio: %S
+mailListNameExistsTitle=Rhestr E-bostio'n Bodoli Eisoes
+mailListNameExistsMessage=Mae Rhestr E-bostio o'r enw yna'n bodoli eisoes. Dewiswch enw arall.
+
+propertyPrimaryEmail=E-bost
+propertyListName=Enw Rhestr
+propertySecondaryEmail=E-bost Ychwanegol
+propertyNickname=Llysenw
+propertyDisplayName=Enw Dangos
+propertyWork=Gwaith
+propertyHome=Cartref
+propertyFax=Ffacs
+propertyCellular=Symudol
+propertyPager=Swnyn
+propertyBirthday=Pen-blwydd
+propertyCustom1=Cyfaddasu 1
+propertyCustom2=Cyfaddasu 2
+propertyCustom3=Cyfaddas 3
+propertyCustom4=Cyfaddasu 4
+
+propertyGtalk=Google Talk
+propertyAIM=AIM
+propertyYahoo=Yahoo!
+propertySkype=Skype
+propertyQQ=QQ
+propertyMSN=MSN
+propertyICQ=ICQ
+propertyXMPP=Enw Jabber
+propertyIRC=Llysenw IRC
+
+## LOCALIZATION NOTE (cityAndStateAndZip):
+## %1$S is city, %2$S is state, %3$S is zip
+cityAndStateAndZip=%1$S, %2$S %3$S
+## LOCALIZATION NOTE (cityAndStateNoZip):
+## %1$S is city, %2$S is state
+cityAndStateNoZip=%1$S, %2$S
+## LOCALIZATION NOTE (cityOrStateAndZip):
+## %1$S is city or state, %2$S is zip
+cityOrStateAndZip=%1$S %2$S
+
+stateZipSeparator=
+
+prefixTo=At
+prefixCc=Cc
+prefixBcc=Bcc
+addressBook=Llyfr Cyfeiriadau
+
+# Contact photo management
+browsePhoto=Llun y Cysylltiad
+stateImageSave=Cadw'r ddelwedd…
+errorInvalidUri=Gwall: delwedd ffynhonnell annilys.
+errorNotAvailable=Gwall: nid oes modd cysylltu â'r ffeil.
+errorInvalidImage=Gwall: Dim ond delweddau JPG, PNG a GIF sy'n cael eu cynnal.
+errorSaveOperation=Gwall: Methu cadw'r ddelwedd.
+
+# mailnews.js
+ldap_2.servers.pab.description=Llyfr Cyfeiriadau Personol
+ldap_2.servers.history.description=Cyfeiriadau wedi'u Casglu
+## LOCALIZATION NOTE (ldap_2.servers.osx.description is only used on Mac OS X)
+ldap_2.servers.osx.description=Llyfr Cyfeiriadau Mac OS X
+## LOCALIZATION NOTE (ldap_2.servers.outlook.description is only used on Windows)
+ldap_2.servers.outlook.description=Llyfrau Cyfeiriadau Outlook
+
+# status bar stuff
+## LOCALIZATION NOTE (totalContactStatus):
+## %1$S is address book name, %2$S is contact count
+totalContactStatus=Pob cysylltiad yn %1$S: %2$S
+noMatchFound=Heb ganfod cydweddion
+## LOCALIZATION NOTE (matchesFound1):
+## Semicolon-separated list of singular and plural forms.
+## See: https://developer.mozilla.org/docs/Mozilla/Localization/Localization_and_Plurals
+## #1 is the number of matching contacts found
+matchesFound1=Heb ganfod dim cydweddiadau;Wedi canfod #1 sy'n cydweddu;Wedi canfod #1 sy'n cydweddu;Wedi canfod #1 sy'n cydweddu;Wedi canfod #1 sy'n cydweddu;Wedi canfod #1 sy'n cydweddu
+
+## LOCALIZATION NOTE (contactsCopied): Semi-colon list of plural forms
+## %1$S is the number of contacts that were copied. This should be used multiple
+## times wherever you need it. Do not replace by %S.
+contactsCopied=%1$S cysylltiad wedi'i gopïo%1$S cysylltiadau wedi'u copïo
+
+## LOCALIZATION NOTE (contactsMoved): Semi-colon list of plural forms
+## %1$S is the number of contacts that were moved. This should be used multiple
+## times wherever you need it. Do not replace by %S.
+contactsMoved=%1$S cysylltiad wedi'i symud%1$S cysylltiadau wedi'u symud
+
+# LDAP directory stuff
+invalidName=Rhoi Enw dilys.
+invalidHostname=Rhowch Enw Gwesteiwr dilys.
+invalidPortNumber=Rhowch Rif Porth dilys.
+invalidResults=Rhowch rif dilys ym maes y canlyniadau.
+abReplicationOfflineWarning=Rhaid bod ar-lein i ddyblygu LDAP.
+abReplicationSaveSettings=Rhaid cadw gosodiadau cyn bod modd llwytho i lawr.
+
+# For importing / exporting
+## LOCALIZATION NOTE (ExportAddressBookNameTitle): %S is the name of exported addressbook
+ExportAddressBookNameTitle=Allforio Llyfr Cyfeiriadau - %S
+LDIFFiles=LDIF
+CSVFiles=Gwahanwyd gan Atalnod
+CSVFilesSysCharset=Gwahanwyd gan Atalnod (Set Nod y System)
+CSVFilesUTF8=Gwahanwyd gan Atalnod (UTF-8)
+TABFiles=Diderfyn Tab
+TABFilesSysCharset=Diderfyn Tab (Set Nod y System)
+TABFilesUTF8=Diderfyn Tab (UTF-8)
+VCFFiles=vCard
+SupportedABFiles=Ffeiliau Llyfr Cyfeiriad sy'n Cael eu Cynnal
+failedToExportTitle=Methodd Allforio
+failedToExportMessageNoDeviceSpace=Methodd allforio'r llyfr cyfeiriadau, dim lle ar y ddyfais.
+failedToExportMessageFileAccessDenied=Methodd allforio'r llyfr cyfeiriadau, gwrthodwyd mynediad at y ffeil.
+
+# For getting authDN for replication using dlg box
+AuthDlgTitle=Dyblygu Llyfr Cyfeiriadau LDAP
+AuthDlgDesc=I gael mynediad at weinydd y cyfeiriadur, rhowch eich enw defnyddiwr a chyfrinair.
+
+# LOCALIZATION NOTE(joinMeInThisChat)
+# use + for spaces
+joinMeInThisChat=Ymuno+â+mi+yn+y+Sgwrs.
+
+# For printing
+headingHome=Cartref
+headingWork=Gwaith
+headingOther=Arall
+headingChat=Sgwrsio
+headingPhone=Ffôn
+headingDescription=Disgrifiad
+headingAddresses=Cyfeiriadau
+
+## For address books
+addressBookTitleNew=Llyfr Cyfeiriadau Newydd
+# LOCALIZATION NOTE (addressBookTitleEdit):
+# %S is the current name of the address book.
+# Example: My Custom AB Properties
+addressBookTitleEdit=Priodweddau %S
+duplicateNameTitle=Enw Llyfr Cyfeiriadau Dyblyg
+# LOCALIZATION NOTE (duplicateNameText):
+# Don't localize "\n• %S" unless your local layout comes out wrong.
+# %S is the name of the existing address book.
+# Example: An address book with this name already exists:
+#          • My Custom AB
+duplicateNameText=Mae llyfr cyfeiriadau gyda'r enw hwn yn bodoli eisoes:\n %S
+
+# For corrupt .mab files
+corruptMabFileTitle=Ffeil Llyfr Cyfeiriadau Llwgr
+corruptMabFileAlert=Methu darllen un o ffeiliau llyfr cyfeiriadau (%1$S file). Bydd ffeil %2$S newydd yn cael ei greu yn yr un cyfeiriadur a chopi wrth gefn o'r enw %3$S.
+
+# For locked .mab files
+lockedMabFileTitle=Methu Llwytho Ffeil Llyfr Cyfeiriadau
+lockedMabFileAlert=Methu llwytho ffeil llyfr cyfeiriadau %S. Gall fod yn darllen yn unig, neu wedi ei gloi gan raglen arall. Ceisiwch eto yn ddiweddarach.
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/ldapAutoCompErrs.properties b/l10n-cy/mail/chrome/messenger/addressbook/ldapAutoCompErrs.properties
new file mode 100644
index 0000000000..096f8e817a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/ldapAutoCompErrs.properties
@@ -0,0 +1,109 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# These are error strings for problems that happen while in the
+# various states declared in nsILDAPAutoCompFormatter.idl.  Note that
+# the number that indexes each error state is the same as the number 
+# corresponding to that state in nsILDAPAutoCompFormatter.idl.
+
+# These are error strings for problems that happen while in the
+# various states declared in nsILDAPAutoCompFormatter.idl.  Note that
+# the number that indexes each error state is the same as the number
+# corresponding to that state in nsILDAPAutoCompFormatter.idl.
+
+## @name ERR_STATE_UNBOUND
+## @loc none
+0=Anhawster cychwyn LDAP
+
+## @name ERR_STATE_INITIALIZING
+## @loc none
+1=Methodd cysylltiad gweinydd LDAP
+
+## @name ERR_STATE_BINDING
+## @loc none
+2=Methodd cysylltiad gweinydd LDAP
+
+## @name ERR_STATE_BOUND
+## @loc none
+3=Problem cyfathrebu gweinydd LDAP
+
+## @name ERR_STATE_SEARCHING
+## @loc none
+4=Problem chwilio gweinydd LDAP
+
+
+# The format of the alert dialog itself
+#
+## @name ALERT_FORMAT
+## @loc None of %1$S, %2$S and %3$S should be localized. 
+##      %1$S is the error code itself, %2$S is an LDAP SDK error message from
+##      chrome://mozldap/locale/ldap.properties, and %3$S is a hint relating
+##      to that specific error, found in this file.
+errorAlertFormat=Cod gwall %1$S: %2$S\n\n %3$S
+
+## The following errors are for error codes other than LDAP-specific ones.
+## Someday mozilla will actually have a system for mapping nsresults to
+## error strings that's actually widely used, unlike nsIErrorService.  But
+## until it does, these strings live here...
+
+## @name HOST_NOT_FOUND
+## @loc none
+5000=Methu canfod gwesteiwr
+
+## @name GENERIC_ERROR
+## @loc none
+9999=Gwall anhysbys
+
+
+# Hints to for the user, associated with specific error codes (ie error code
+# + 10000)
+
+
+## @name TIMELIMIT_EXCEEDED_HINT
+## @loc none
+10003=Ceisiwch eto yn ddiweddarach neu cysylltwch â'ch Gweinyddwr System.
+
+## @name STRONGAUTH_REQUIRED_HINT
+## @loc none
+10008=Nid yw dilysu cryf yn cael ei gynnal ar hyn o bryd.
+
+## @name INVALID_SYNTAX_HINT
+## @loc none
+10021=Gwiriwch fod yr hidl chwilio'n gywir a cheisiwch eto, neu cysylltwch â'ch Gweinyddwr System. I wirio fod yr hidl chwilio'n gywir, o'r ddewislen Golygu dewiswch Dewis ac yna dewis E-bost a Grwpiau Newyddion ac yna dewis Cyfeirio. Cliciwch ar Golygu Cyfeiriaduron a dewis y gweinydd LDAP sy'n cael ei ddefnyddio. Cliciwch ar Golygu ac yna clicio ar Uwch i ddangos yr Hidl Chwilio.
+
+## @name NO_SUCH_OBJECT_HINT
+## @loc none
+10032=Gwiriwch fod y Base DN yn gywir a cheisiwch eto, neu cysylltwch â'ch Gweinyddwr System. I wirio fod y Base DN yn gywir, o'r ddewislen Golygu dewiswch Dewisiadau, yna E-bost a Grwpiau Newyddion, dewis Cyfeirio. Cliciwch Golygu Cyfeiriaduron, a dewis y gweinydd LDAP sy'n cael ei ddefnyddio. Cliciwch Golygu i ddangos Base DN.
+
+## @name BUSY_HINT
+## @loc none
+10051=Ceisiwch eto'n ddiweddarach.
+
+## @name SERVER_DOWN_HINT
+## @loc none
+10081=Gwiriwch fod Enw Gwesteiwr a Rhif Porth yn gywir a cheisiwch eto neu cysylltwch â'ch Gweinyddwr System. I wirio fod yr Enw Gwesteiwr a'r Rhif Porth cywir, o'r ddewislen Golygu dewiswch Dewisiadau, yna E-bost a Grwpiau Newyddion, dewis Cyfeirio. Cliciwch Golygu Cyfeiriaduron, a dewis y gweinydd LDAP sy'n cael ei ddefnyddio. Cliciwch Golygu i ddangos yr Enw gwesteiwr. Cliciwch Uwch i ddangos Rhif y Porth.
+
+## @name TIMEOUT_HINT
+## @loc none
+10085=Ceisiwch eto'n ddiweddarach.
+
+## @name FILTER_ERROR_HINT
+## @loc none
+10087=Gwiriwch fod yr hidl chwilio'n gywir a cheisiwch eto, neu cysylltwch a'ch Gweinyddwr System. I wirio fod yr hidl chwilio'n gywir, o'r ddewislen Golygu dewiswch Dewis ac yna dewis E-bost a Grwpiau Newyddion ac yna dewis Cyfeirio. Cliciwch ar Golygu Cyfeiriaduron a dewis y gweinydd LDAP sy'n cael ei ddefnyddio. Cliciwch ar Golygu ac yna clicio ar Uwch i ddangos yr Hidl Chwilio.
+
+## @name NO_MEMORY_HINT
+## @loc none
+10090=Caewch rhai ffenestri eraill a/neu gymwysiadau a cheisiwch eto.
+
+## @name CONNECT_ERROR_HINT
+## @loc none
+10091=Gwiriwch fod Enw Gwesteiwr a Rhif Porth yn gywir a cheisiwch eto neu cysylltwch â'ch Gweinyddwr System. I wirio fod yr Enw Gwesteiwr a'r Rhif Porth cywir, o'r ddewislen Golygu dewiswch Dewisiadau, yna E-bost a Grwpiau Newyddion, dewis Cyfeirio. Cliciwch Golygu Cyfeiriaduron, a dewis y gweinydd LDAP sy'n cael ei ddefnyddio. Cliciwch Golygu i ddangos yr Enw gwesteiwr. Cliciwch Uwch i ddangos Rhif y Porth.
+
+## @name HOST_NOT_FOUND_HINT
+## @loc none
+15000=Gwiriwch fod Enw Gwesteiwr yn gywir a cheisiwch eto neu cysylltwch â'ch Gweinyddwr System. I wirio fod yr Enw Gwesteiwr cywir, o'r ddewislen Golygu dewiswch Dewisiadau, yna E-bost a Grwpiau Newyddion, dewis Cyfeirio. Clicio Golygu Cyfeiriaduron, a dewis y gweinydd LDAP sy'n cael ei ddefnyddio. Cliciwch Golygu i ddangos yr Enw Gwesteiwr.
+
+## @name GENERIC_HINT
+## @loc none
+19999=Cysylltwch â'ch Gweinyddwr System.
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/pref-directory-add.dtd b/l10n-cy/mail/chrome/messenger/addressbook/pref-directory-add.dtd
new file mode 100644
index 0000000000..4e18369be7
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/pref-directory-add.dtd
@@ -0,0 +1,45 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY directoryName.label               "Enw: ">
+<!ENTITY directoryName.accesskey           "E">
+<!ENTITY directoryHostname.label           "Enw Gwesteiwr: ">
+<!ENTITY directoryHostname.accesskey       "G">
+<!ENTITY directoryBaseDN.label             "DN Bôn: ">
+<!ENTITY directoryBaseDN.accesskey         "B">
+<!ENTITY findButton.label                  "Canfod">
+<!ENTITY findButton.accesskey              "f">
+<!ENTITY directorySecure.label             "Defnyddio cysylltiad diogel (SSL)">
+<!ENTITY directorySecure.accesskey         "D">
+<!ENTITY directoryLogin.label              "Rhwymo DN: ">
+<!ENTITY directoryLogin.accesskey          "R">
+<!ENTITY General.tab                       "Cyffredinol">
+<!ENTITY Offline.tab                       "All-lein">
+<!ENTITY Advanced.tab                      "Uwch">
+<!ENTITY portNumber.label                  "Rhif porth: ">
+<!ENTITY portNumber.accesskey              "p">
+<!ENTITY searchFilter.label                "Hidl chwilio: ">
+<!ENTITY searchFilter.accesskey            "H">
+<!ENTITY scope.label                       "Amrediad: ">
+<!ENTITY scope.accesskey                   "A">
+<!ENTITY scopeOneLevel.label               "Un Lefel">
+<!ENTITY scopeOneLevel.accesskey           "U">
+<!ENTITY scopeSubtree.label                "Is-goeden">
+<!ENTITY scopeSubtree.accesskey            "I">
+<!ENTITY return.label                      "Peidio dychwelyd mwy na">
+<!ENTITY return.accesskey                  "P">
+<!ENTITY results.label                     "canlyniadau">
+<!ENTITY offlineText.label                 "Gallwch lwytho i lawr copi lleol o'r cyfeiriadur hwn ar gyfer defnydd all-lein.">
+<!ENTITY saslMechanism.label               "Dull mewngofnodi: ">
+<!ENTITY saslMechanism.accesskey           "m">
+<!ENTITY saslOff.label                     "Syml">
+<!ENTITY saslOff.accesskey                 "S">
+<!ENTITY saslGSSAPI.label                  "Kerberos (GSSAPI)">
+<!ENTITY saslGSSAPI.accesskey              "K">
+<!-- Localization note: this is here because the width of the dialog 
+     is determined by the width of the base DN box; and that is likely
+     to vary somewhat with the language.
+-->
+
+<!ENTITY newDirectoryWidth                 "36em">
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/pref-directory.dtd b/l10n-cy/mail/chrome/messenger/addressbook/pref-directory.dtd
new file mode 100644
index 0000000000..93db1fa36e
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/pref-directory.dtd
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- LOCALIZATION NOTE (window.title) : do not translate "LDAP" in below line -->
+
+<!ENTITY pref.ldap.window.title    "Gweinyddion Cyfeiriadur LDAP">
+<!-- LOCALIZATION NOTE (directories.label) : do not translate "LDAP" in below line -->
+<!ENTITY directories.label         "Gweinyddwyr Cyfeiriadur LDAP:">
+<!-- LOCALIZATION NOTE (directoriesText.label) : do not translate "LDAP" in below line -->
+<!ENTITY directoriesText.label     "Dewiswch Gyfeiriadur gweinydd LDAP:">
+<!ENTITY directoriesText.accesskey "D">
+<!ENTITY addDirectory.label        "Ychwanegu">
+<!ENTITY addDirectory.accesskey    "Y">
+<!ENTITY editDirectory.label       "Golygu">
+<!ENTITY editDirectory.accesskey   "G">
+<!ENTITY deleteDirectory.label     "Dileu">
+<!ENTITY deleteDirectory.accesskey "D">
diff --git a/l10n-cy/mail/chrome/messenger/addressbook/replicationProgress.properties b/l10n-cy/mail/chrome/messenger/addressbook/replicationProgress.properties
new file mode 100644
index 0000000000..26a24ca271
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/addressbook/replicationProgress.properties
@@ -0,0 +1,20 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+replicationStarted=Dyblygu wedi cychwyn…
+changesStarted=Wedi cychwyn canfod newidiadau i'w dyblygu…
+replicationSucceeded=Llwyddodd y dyblygu
+replicationFailed=Methodd y dyblygu
+replicationCancelled=Diddymwyd y dyblygu
+# LOCALIZATION NOTE
+# do not localize %S.  %S is the current entry number (an integer)
+currentCount=Dyblygu cofnod cyfeiriadur: %S
+
+downloadButton=Llwytho i Lawr Nawr
+downloadButton.accesskey=L
+cancelDownloadButton=Diddymu Llwytho i Lawr
+cancelDownloadButton.accesskey=D
+
+directoryTitleNew=Cyfeiriadur LDAP Newydd
+## LOCALIZATION NOTE (directoryTitleEdit): %S will be replaced by the LDAP directory's display name
+directoryTitleEdit=Priodweddau %S
diff --git a/l10n-cy/mail/chrome/messenger/am-addressing.dtd b/l10n-cy/mail/chrome/messenger/am-addressing.dtd
new file mode 100644
index 0000000000..bb0c68dce8
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-addressing.dtd
@@ -0,0 +1,51 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- extracted from am-addressing.xul -->
+
+<!-- extracted from am-addressing.xhtml -->
+
+<!ENTITY addressing.label          "Ysgrifennu a Chyfeiriadau">
+<!ENTITY addressingGroupTitle.label "Cyfeirio">
+<!ENTITY addressingText.label      "Wrth chwilio am gyfeiriadau:">
+<!-- LOCALIZATION NOTE (override.label) : do not translate "LDAP" in below line -->
+<!ENTITY useGlobal.label           "Defnyddio fy newisiadau gweinydd LDAP eang ar gyfer y cyfrif hwn">
+<!ENTITY useGlobal.accesskey       "D">
+<!ENTITY editDirectories.label     "Golygu Cyfeiriaduron…">
+<!ENTITY editDirectories.accesskey "C">
+<!-- LOCALIZATION NOTE (directories.label) : do not translate "LDAP" in below line -->
+<!ENTITY directories.label         "Defnyddio gweinydd LDAP gwahanol:">
+<!ENTITY directories.accesskey     "D">
+<!ENTITY directoriesNone.label     "Dim">
+
+<!-- am-addressing.xul -->
+
+<!-- am-addressing.xhtml -->
+
+<!ENTITY compositionGroupTitle.label          "Ysgrifennu">
+<!-- LOCALIZATION NOTE (useHtml.label) : do not translate "html" in below line -->
+<!ENTITY useHtml.label                        "Ysgrifennu negeseuon yn fformat HTML">
+<!ENTITY useHtml.accesskey                    "Y">
+<!ENTITY autoQuote.label                      "Dyfynnu'r neges wreiddiol yn awtomatig wrth ateb">
+<!ENTITY autoQuote.accesskey                  "D">
+<!-- LOCALIZATION NOTE (quoting.label): This will concatenate with the 4 strings that follow. -->
+<!ENTITY quoting.label                        "Pan yn dyfynnu">
+<!ENTITY quoting.accesskey                    "d">
+<!ENTITY aboveQuote.label                     "cychwyn fy ateb uwchlaw'r dyfyniad">
+<!ENTITY belowQuote.label                     "cychwyn fy ateb o dan y dyfyniad">
+<!ENTITY selectAndQuote.label                 "dewis y dyfyniad">
+<!ENTITY place.label                          "a gosod fy llofnod">
+<!ENTITY place.accesskey                      "l">
+<!ENTITY belowText.label                      "islaw'r dyfyniad (argymhellir)">
+<!ENTITY aboveText.label                      "o dan fy ateb (uwchlaw'r dyfyniad)">
+<!ENTITY includeSigOnReply.label              "Cynnwys llofnod mewn atebion">
+<!ENTITY includeSigOnReply.accesskey          "a">
+<!ENTITY includeSigOnForward.label            "Cynnwys llofnod wrth anfon ymlaen">
+<!ENTITY includeSigOnForward.accesskey        "y">
+
+<!ENTITY globalComposingPrefs.label           "Dewisiadau Cyfansoddi Eang…">
+<!ENTITY globalComposingPrefs.accesskey       "D">
+
+<!ENTITY globalAddressingPrefs.label          "Dewisiadau Cyfansoddi Eang…">
+<!ENTITY globalAddressingPrefs.accesskey      "C">
diff --git a/l10n-cy/mail/chrome/messenger/am-advanced.dtd b/l10n-cy/mail/chrome/messenger/am-advanced.dtd
new file mode 100644
index 0000000000..763eaaa5b6
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-advanced.dtd
@@ -0,0 +1,31 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- extracted from am-advanced.xul -->
+<!-- LOCALIZATION NOTE (smtpServer.label): do not translate "SMTP" in below line -->
+
+
+<!-- extracted from am-advanced.xhtml -->
+
+<!ENTITY smtpServer.label "Gosodiadau Gweinydd Anfon (SMTP)">
+<!-- LOCALIZATION NOTE (smtpDescription.label): do not translate "SMTP" in below line -->
+
+<!ENTITY smtpDescription.label "Wrth reoli eich hunaniaethau mae modd defnyddio gweinydd o&apos;r rhestr hon drwy ei dewis fel y Gweinydd Anfon (SMTP) neu mae modd defnyddio&apos;r gweinydd rhagosodedig o&apos;r rhestr hon drwy ddewis &quot;Defnyddio&apos;r Gweinydd Rhagosodedig&quot;.">
+
+<!ENTITY smtpListAdd.label  "Ychwanegu…">
+<!ENTITY smtpListAdd.accesskey  "Y">
+<!ENTITY smtpListEdit.label "Golygu…">
+<!ENTITY smtpListEdit.accesskey "G">
+<!ENTITY smtpListDelete.label "Tynnu">
+<!ENTITY smtpListDelete.accesskey "T">
+<!ENTITY smtpListSetDefault.label "Gosod y Rhagosodiad">
+<!ENTITY smtpListSetDefault.accesskey "R">
+
+<!ENTITY serverDetails.label "Manylion y gweinydd hwn:">
+<!ENTITY serverDescription.label "Disgrifiad: ">
+<!ENTITY serverName.label "Enw'r Gweinydd: ">
+<!ENTITY serverPort.label "Porth: ">
+<!ENTITY userName.label   "Enw Defnyddiwr: ">
+<!ENTITY connectionSecurity.label "Diogelwch y Cysylltiad: ">
+<!ENTITY authMethod.label   "Dull dilysu: ">
diff --git a/l10n-cy/mail/chrome/messenger/am-archiveoptions.dtd b/l10n-cy/mail/chrome/messenger/am-archiveoptions.dtd
new file mode 100644
index 0000000000..b1517343ce
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-archiveoptions.dtd
@@ -0,0 +1,26 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- extracted from am-archiveoptions.xul -->
+
+
+<!-- extracted from am-archiveoptions.xhtml -->
+
+<!ENTITY dialogTitle.label "Dewisiadau Archifo">
+<!ENTITY archiveGranularityPrefix.label "Wrth archifo negeseuon, eu rhoi yn:">
+<!ENTITY archiveFlat.label "Ffolder unigol">
+<!ENTITY archiveFlat.accesskey "u">
+<!ENTITY archiveYearly.label "Ffolderi archif blynyddol">
+<!ENTITY archiveYearly.accesskey "b">
+<!ENTITY archiveMonthly.label "Ffolderi archif misol">
+<!ENTITY archiveMonthly.accesskey "m">
+<!ENTITY keepFolderStructure.label "Cadw strwythur cyfredol ffolderi negeseuon archifwyd">
+<!ENTITY keepFolderStructure.accesskey "s">
+<!ENTITY archiveExample.label "Esiampl">
+<!-- LOCALIZATION NOTE (archiveFolderName.label): this should match the default
+     name for the "Archives" folder -->
+<!ENTITY archiveFolderName.label "Archifau">
+<!-- LOCALIZATION NOTE (inboxFolderName.label): this should match the default
+     name for the "Inbox" folder -->
+<!ENTITY inboxFolderName.label "Derbyn">
diff --git a/l10n-cy/mail/chrome/messenger/am-copies.dtd b/l10n-cy/mail/chrome/messenger/am-copies.dtd
new file mode 100644
index 0000000000..d791632db6
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-copies.dtd
@@ -0,0 +1,53 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- extracted from am-copies.xul -->
+
+
+<!-- extracted from am-copies.xhtml -->
+
+<!ENTITY copyAndFolderTitle.label "Copïau a Ffolderi">
+<!ENTITY sendingPrefix.label "Wrth anfon negeseuon, yn awtomatig: ">
+<!ENTITY fccMailFolder.label "Rhoi copi yn:">
+<!ENTITY fccMailFolder.accesskey "c">
+<!ENTITY fccReplyFollowsParent.label "Rhoi atebion yn ffolder y negeseuon sy'n derbyn ateb">
+<!ENTITY fccReplyFollowsParent.accesskey "a">
+<!-- LOCALIZATION NOTE (ccAddress.label): do not translate "Cc" in below line -->
+<!ENTITY ccAddress.label "Cc y cyfeiriadau e-bost hyn:">
+<!ENTITY ccAddress.accesskey "C">
+<!ENTITY ccAddressList.placeholder "Gwahanu cyfeiriad gyda chollnod">
+<!-- LOCALIZATION NOTE (bccAddress.label): do not translate "Bcc" in below line -->
+<!ENTITY bccAddress.label "Bcc y cyfeiriadau e-bost hyn:">
+<!ENTITY bccAddress.accesskey "B">
+<!ENTITY bccAddressList.placeholder "Gwahanu cyfeiriad gyda chollnod">
+<!ENTITY saveMessageDlg.label "Dangos deialog cadarnhau wrth i negeseuon gael eu cadw">
+<!ENTITY saveMessageDlg.accesskey "g">
+<!-- LOCALIZATION NOTE (sentFolderOn.label): OK to translate this, bug #57440 -->
+<!ENTITY sentFolderOn.label "Ffolder &quot;Anfonwyd&quot; ar:">
+<!ENTITY sentFolderOn.accesskey "n">
+<!ENTITY sentInOtherFolder.label "Arall:">
+<!ENTITY sentInOtherFolder.accesskey "A">
+<!-- LOCALIZATION NOTE (archivesFolderOn.label): OK to translate this, bug #57440 -->
+<!ENTITY archivesTitle.label "Archif Negeseuon">
+<!ENTITY keepArchives.label "Cadw archif negeseuon yn:">
+<!ENTITY keepArchives.accesskey "a">
+<!ENTITY archiveHierarchyButton.label "Dewisiadau archifo…">
+<!ENTITY archiveHierarchyButton.accesskey "w">
+<!ENTITY archivesFolderOn.label "Ffolder &quot;Archif&quot; yn:">
+<!ENTITY archivesFolderOn.accesskey "F">
+<!ENTITY archiveInOtherFolder.label "Arall:">
+<!ENTITY archiveInOtherFolder.accesskey "r">
+<!ENTITY specialFolders.label "Drafftiau a Thempledi">
+<!ENTITY keepDrafts2.label "Cadw negeseuon drafft yn:">
+<!-- LOCALIZATION NOTE (draftsFolderOn.label): OK to translate this, bug #57440 -->
+<!ENTITY draftsFolderOn.label "Ffolder &quot;Drafftiau&quot; yn:">
+<!ENTITY draftsFolderOn.accesskey "D">
+<!ENTITY draftInOtherFolder.label "Arall:">
+<!ENTITY draftInOtherFolder.accesskey "l">
+<!ENTITY keepTemplates.label "Cadw templedi negeseuon yn:">
+<!-- LOCALIZATION NOTE (templatesFolderOn.label): OK to translate this, bug #57440 -->
+<!ENTITY templatesFolderOn.label "Ffolder &quot;Templedi&quot; yn:">
+<!ENTITY templatesFolderOn.accesskey "T">
+<!ENTITY templateInOtherFolder.label "Arall:">
+<!ENTITY templateInOtherFolder.accesskey "r">
diff --git a/l10n-cy/mail/chrome/messenger/am-e2e.properties b/l10n-cy/mail/chrome/messenger/am-e2e.properties
new file mode 100644
index 0000000000..dbc7881dde
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-e2e.properties
@@ -0,0 +1,5 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+prefPanel-e2e=Amgryptio Pen-i-Ben
diff --git a/l10n-cy/mail/chrome/messenger/am-identities-list.dtd b/l10n-cy/mail/chrome/messenger/am-identities-list.dtd
new file mode 100644
index 0000000000..24527f0212
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-identities-list.dtd
@@ -0,0 +1,15 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY identitiesListManageDesc.label "Rheoli hunaniaethau'r cyfrif hwn. Bydd yr hunaniaeth gyntaf yn cael ei ddefnyddio drwy ragosodiad.">
+<!ENTITY identitiesListAdd.label  "Ychwanegu…">
+<!ENTITY identitiesListAdd.accesskey  "Y">
+<!ENTITY identitiesListEdit.label "Golygu…">
+<!ENTITY identitiesListEdit.accesskey "G">
+<!ENTITY identitiesListDefault.label "Gosod y Rhagosodiad">
+<!ENTITY identitiesListDefault.accesskey "R">
+<!ENTITY identitiesListDelete.label "Dileu">
+<!ENTITY identitiesListDelete.accesskey "D">
+<!ENTITY identitiesListClose.label "Cau">
+<!ENTITY identitiesListClose.accesskey "u">
diff --git a/l10n-cy/mail/chrome/messenger/am-identity-edit.dtd b/l10n-cy/mail/chrome/messenger/am-identity-edit.dtd
new file mode 100644
index 0000000000..ceb7e18e09
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-identity-edit.dtd
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- LOCALIZATION NOTE (identityDialog.style): This value should be roughly
+     equal to the value of accountManager.size entity minus the value
+     of accountTree.width entity. -->
+
+<!ENTITY identityListDesc.label "Ffurfweddu gosodiadau'r hunaniaeth yma:">
+
+<!ENTITY settingsTab.label       "Gosodiadau">
+<!ENTITY copiesFoldersTab.label "Copïau a Ffolderi">
+<!ENTITY addressingTab.label    "Ysgrifennu a Chyfeiriadau">
+
+<!ENTITY publicData.label        "Data Cyhoeddus">
+<!ENTITY privateData.label       "Data Preifat">
+<!ENTITY identityAlias.label     "Label Hunaniaeth:">
+<!ENTITY identityAlias.accesskey "H">
diff --git a/l10n-cy/mail/chrome/messenger/am-im.dtd b/l10n-cy/mail/chrome/messenger/am-im.dtd
new file mode 100644
index 0000000000..f06259ec14
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-im.dtd
@@ -0,0 +1,16 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY accountWindow.title           "Priodweddau cyfrif">
+<!ENTITY accountWindow.width           "300">
+<!ENTITY account.general               "Cyffredinol">
+<!ENTITY account.advanced              "Dewisiadau Uwch">
+<!ENTITY account.name                  "Enw Defnyddiwr:">
+<!ENTITY account.password              "Cyfrinair:">
+<!ENTITY account.alias                 "Enw arall:">
+<!ENTITY account.newMailNotification   "Hysbysu ar E-bost newydd">
+<!ENTITY account.autojoin              "Sianeli Awto-Gyfuno:">
+<!ENTITY account.proxySettings.caption "Gosodiadau Dirprwyol:">
+<!ENTITY account.proxySettings.change.label     "Newid…">
+<!ENTITY account.proxySettings.change.accessKey "N">
diff --git a/l10n-cy/mail/chrome/messenger/am-junk.dtd b/l10n-cy/mail/chrome/messenger/am-junk.dtd
new file mode 100644
index 0000000000..d50ab0e944
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-junk.dtd
@@ -0,0 +1,31 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY junkSettings.label "Gosodiadau Sbam">
+<!ENTITY trainingDescription.label "Os yw wedi'i alluogi, bydd rhaid i chi ddysgu &brandShortName; i adnabod sbam drwy ddefnyddio'r botwm bar offer Sbam i farcio negeseuon fel sbam neu beidio. Rhaid i chi adnabod negeseuon sbam a'r rhai nad ydynt yn sbam. Wedyn bydd &brandShortName; yn gallu nodi sbam yn awtomatig.">
+<!ENTITY level.label "Galluogi rheolaeth addasol e-bost sbam ar gyfer y cyfrif hwn">
+<!ENTITY level.accesskey "s">
+
+<!ENTITY move.label "Symud sbam newydd i:">
+<!ENTITY move.accesskey "S">
+<!ENTITY junkFolderOn.label "Ffolder &quot;Sbam&quot; yn:">
+<!ENTITY junkFolderOn.accesskey "F">
+<!ENTITY otherFolder.label "Arall:">
+<!ENTITY otherFolder.accesskey "a">
+<!ENTITY purge1.label "Dileu'n awtomatig sbam hŷn na">
+<!ENTITY purge1.accesskey "D">
+<!ENTITY purge2.label "diwrnod">
+
+<!ENTITY whitelistHeader.label "Peidio marcio e-bost fel sbam yn awtomatig os yw'r anfonwr yn: ">
+<!ENTITY whitelistHeader.accesskey "P">
+
+<!ENTITY ispHeadersWarning.label "Os wedi ei alluogi bydd &brandShortName; yn ystyried yn awtomatig fod negeseuon wedi eu marcio gan y dosbarthydd allanol yn sbam.">
+<!ENTITY ispHeaders.label "Ymddiried ym mhenynnau e-bost sbam wedi'u gosod gan: ">
+<!ENTITY ispHeaders.accesskey "Y">
+
+<!ENTITY junkClassification.label "Dewis">
+<!ENTITY junkActions.label "Cyrchfan a Chadw">
+
+<!ENTITY globalJunkPrefs.label "Dewisiadau Sbam Eang…">
+<!ENTITY globalJunkPrefs.accesskey "E">
diff --git a/l10n-cy/mail/chrome/messenger/am-main.dtd b/l10n-cy/mail/chrome/messenger/am-main.dtd
new file mode 100644
index 0000000000..18b5ecfc62
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-main.dtd
@@ -0,0 +1,49 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- extracted from am-main.xul -->
+
+<!-- extracted from am-main.xhtml -->
+
+<!ENTITY accountTitle.label "Gosodiadau'r Cyfrif">
+<!ENTITY accountName.label "Enw Cyfrif:">
+<!ENTITY accountName.accesskey "C">
+<!ENTITY identityTitle.label "Hunaniaeth Rhagosodedig">
+<!ENTITY identityDesc.label "Mae gan bob cyfrif hunaniaeth, sef y wybodaeth mae pobl eraill yn ei weld pan yn darllen eich negeseuon.">
+<!ENTITY name.label "Eich Enw:">
+<!ENTITY name.accesskey "E">
+<!ENTITY email.label "Cyfeiriad E-bost:">
+<!ENTITY email.accesskey "y">
+<!ENTITY catchAll.label "Ymateb o'r hunaniaeth hon pan fydd y penynnau dosbarthu yn cyfateb:">
+<!ENTITY catchAll.accesskey "d">
+<!ENTITY replyTo.label "Cyfeiriad Ateb Iddo:">
+<!ENTITY replyTo.accesskey "A">
+<!ENTITY replyTo.placeholder "Derbynwyr i ateb i gyfeiriad arall">
+<!ENTITY organization.label "Corff:">
+<!ENTITY organization.accesskey "o">
+<!ENTITY signatureText.label "Testun llofnod:">
+<!ENTITY signatureText.accesskey "T">
+<!ENTITY signatureHtml.label "Defnyddio HTML (e.e., &lt;b&gt;trwm&lt;/b&gt;)">
+<!ENTITY signatureHtml.accesskey "H">
+<!ENTITY signatureFile.label "Atodi llofnod o ffeil (testun, HTML neu ddelwedd):">
+<!ENTITY signatureFile.accesskey "A">
+<!ENTITY edit.label "Golygu…">
+<!ENTITY choose.label "Dewis…">
+<!ENTITY choose.accesskey "D">
+<!ENTITY editVCard.label "Golygu Cerdyn…">
+<!ENTITY editVCard.accesskey "G">
+<!-- LOCALIZATION NOTE (attachVCard.label) : do not translate "vCard" in below line -->
+<!ENTITY attachVCard.label "Atodi fy vCard i negeseuon">
+<!ENTITY attachVCard.accesskey "v">
+
+<!ENTITY manageIdentities.label "Rheoli Hunaniaeth…">
+<!ENTITY manageIdentities.accesskey "H">
+
+<!-- LOCALIZATION NOTE (smtpName.label) : do not translate "SMTP" in below line -->
+<!ENTITY smtpName.label "Gweinydd Anfon (SMTP):">
+<!ENTITY smtpName.accesskey "A">
+<!ENTITY smtpDefaultServer.label "Defnyddio'r Gweinydd Rhagosodedig">
+
+<!ENTITY smtpServerEdit.label "Golygu gweinydd SMTP…">
+<!ENTITY smtpServerEdit.accesskey "S">
diff --git a/l10n-cy/mail/chrome/messenger/am-mdn.dtd b/l10n-cy/mail/chrome/messenger/am-mdn.dtd
new file mode 100644
index 0000000000..c98c1e4473
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-mdn.dtd
@@ -0,0 +1,33 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY pane.title                   "Derbynebau Dychwelyd">
+<!ENTITY useGlobalPrefs.label         "Defnyddio fy newisiadau derbynneb dychwelyd ar gyfer y cyfrif hwn">
+<!ENTITY useGlobalPrefs.accesskey     "D">
+<!ENTITY globalReceipts.label         "Dewisiadau Eang…">
+<!ENTITY globalReceipts.accesskey     "E">
+<!ENTITY useCustomPrefs.label         "Cyfaddasu derbynebau dychwelyd ar gyfer y cyfrif hwn">
+<!ENTITY useCustomPrefs.accesskey     "C">
+<!ENTITY requestReceipt.label         "Wrth anfon negeseuon, gofyn bob tro am dderbynneb dychwelyd">
+<!ENTITY requestReceipt.accesskey     "W">
+<!ENTITY receiptArrive.label          "Pan fydd derbynneb yn cyrraedd:">
+<!ENTITY leaveIt.label                "Gadael yn fy Mlwch Derbyn">
+<!ENTITY leaveIt.accesskey            "D">
+<!-- LOCALIZATION NOTE moveToSent.label Translate: 'Sent' according to Netscape glossary -->
+<!ENTITY moveToSent.label             "Symud i fy ffolder &quot;Anfonwyd&quot;">
+<!ENTITY moveToSent.accesskey         "A">
+<!ENTITY requestMDN.label             "Pan fyddaf yn derbyn cais am dderbynneb dychwelyd:">
+<!ENTITY returnSome.label             "Caniatáu derbynebau dychwelyd ar gyfer rhai negeseuon">
+<!ENTITY returnSome.accesskey         "a">
+<!ENTITY never.label                  "Peidio byth anfon derbynneb dychwelyd">
+<!ENTITY never.accesskey              "P">
+<!ENTITY notInToCc.label              "Os nad wyf yn At neu Cc y neges:">
+<!ENTITY notInToCc.accesskey          "O">
+<!ENTITY outsideDomain.label          "Os yw'r anfonwr o'r tu allan i'm parth:">
+<!ENTITY outsideDomain.accesskey      "s">
+<!ENTITY otherCases.label             "Mewn unrhyw achos arall:">
+<!ENTITY otherCases.accesskey         "M">
+<!ENTITY askMe.label                  "Gofyn i mi">
+<!ENTITY alwaysSend.label             "Anfon pob tro">
+<!ENTITY neverSend.label              "Byth anfon">
diff --git a/l10n-cy/mail/chrome/messenger/am-mdn.properties b/l10n-cy/mail/chrome/messenger/am-mdn.properties
new file mode 100644
index 0000000000..26c43e5a61
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-mdn.properties
@@ -0,0 +1,6 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+## Strings used in prefs.
+prefPanel-mdn=Derbynebau Dychwelyd
diff --git a/l10n-cy/mail/chrome/messenger/am-offline.dtd b/l10n-cy/mail/chrome/messenger/am-offline.dtd
new file mode 100644
index 0000000000..9bafc66069
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-offline.dtd
@@ -0,0 +1,57 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY doNotDownloadPop3Movemail.label "I arbed lle, peidio llwytho i lawr:">
+<!ENTITY doNotDownloadNntp.label "I arbed lle, peidio llwytho i lawr ar gyfer defnydd all-lein:">
+<!ENTITY doNotDownloadImap.label "I arbed lle ar ddisg, mae modd cyfyngu ar lwytho i lawr negeseuon o'r gweinydd a chadw copïau lleol yn ôl oed a maint.">
+<!ENTITY allFoldersOffline2.label "Cadw negesuon ym mhob ffolder ar gyfer y cyfrif yma ar y cyfrifiadur hwn">
+<!ENTITY allFoldersOffline2.accesskey "h">
+<!ENTITY allFoldersOfflineNote.label "Sylw: Bydd newid hwn yn effeithio ar holl ffolderi'r cyfrif hwn. I osod ffolderi unigol, defnyddiwch y botwm Uwch….">
+<!ENTITY offlineNotDownload.label "Negeseuon mwy na">
+<!ENTITY offlineNotDownload.accesskey "N">
+<!ENTITY autosyncNotDownload.label "Peidio llwytho i lawr negeseuon mwy na">
+<!ENTITY autosyncNotDownload.accesskey "P">
+<!ENTITY kb.label "KB">
+<!ENTITY daysOld.label "diwrnod oed">
+<!ENTITY message.label "negeseuon">
+<!ENTITY nntpNotDownloadRead.label "Darllen negeseuon">
+<!ENTITY nntpNotDownloadRead.accesskey "D">
+<!ENTITY nntpDownloadMsg.label "Negeseuon mwy na">
+<!ENTITY nntpDownloadMsg.accesskey "e">
+<!ENTITY retentionCleanup.label "I adfer lle ar ddisg, mae modd dileu hen negesuon yn barhaol.">
+<!ENTITY retentionCleanupImap.label "I adfer lle ar ddisg, mae modd dileu hen negeseuon yn barhaol yn gopïau lleol a'r gwreiddiol ar y gweinydd pell.">
+<!ENTITY retentionCleanupPop.label "I adfer lle ar ddisg, mae modd dileu hen negeseuon yn barhaol gan gynnwys y gwreiddiol ar y gweinydd pell.">
+<!ENTITY retentionKeepMsg.label "Dileu negeseuon sy'n fwy na">
+<!ENTITY retentionKeepMsg.accesskey "D">
+<!ENTITY retentionKeepAll.label "Peidio dileu unrhyw negeseuon">
+<!ENTITY retentionKeepAll.accesskey "e">
+<!ENTITY retentionKeepRecent.label "Dileu pob un heblaw'r mwyaf diweddar">
+<!ENTITY retentionKeepRecent.accesskey "i">
+<!ENTITY retentionApplyToFlagged.label "Cadw negeseuon serennog bob tro">
+<!ENTITY retentionApplyToFlagged.accesskey "s">
+<!ENTITY nntpRemoveMsgBody.label "Tynnu corff neges mwy na">
+<!ENTITY nntpRemoveMsgBody.accesskey "c">
+<!ENTITY offlineSelectNntp.label "Dewis grwpiau newyddion ar gyfer defnydd all-lein…">
+<!ENTITY offlineSelectNntp.accesskey "g">
+<!ENTITY offlineImapAdvancedOffline.label "Uwch…">
+<!ENTITY offlineImapAdvancedOffline.accesskey "U">
+<!ENTITY syncGroupTitle.label "Cydweddu Negeseuon">
+<!ENTITY diskspaceGroupTitle.label "Lle ar Ddisg">
+
+<!-- LOCALIZATION NOTE: (ageAutosyncBefore.label, ageAutosyncMiddle.label, ageAutosyncAfter.label):
+  The entities ageAutosyncBefore.label, ageAutosyncMiddle.label, and ageAutosyncAfter.label appear
+  on a single line within the scope of useAutosync.ByAge as follows:
+
+  &ageAutosyncBefore.label [textbox for autosync value] &ageAutosyncMiddle.label; [dropdown for autosync interval] &ageAutosyncAfter.label;
+-->
+<!ENTITY allAutosync.label               "Cydweddu pob neges yn lleol beth bynnag yw eu hoed">
+<!ENTITY allAutosync.accesskey           "C">
+<!ENTITY ageAutosyncBefore.label         "Cydweddu'r mwyaf diweddar">
+<!ENTITY ageAutosync.accesskey           "z">
+<!ENTITY ageAutosyncMiddle.label         "">
+<!ENTITY dayAgeInterval.label            "Diwrnod">
+<!ENTITY weekAgeInterval.label           "Wythnos">
+<!ENTITY monthAgeInterval.label          "Mis">
+<!ENTITY yearAgeInterval.label           "Blwyddyn">
+<!ENTITY ageAutosyncAfter.label          "">
diff --git a/l10n-cy/mail/chrome/messenger/am-server-advanced.dtd b/l10n-cy/mail/chrome/messenger/am-server-advanced.dtd
new file mode 100644
index 0000000000..5159965a50
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-server-advanced.dtd
@@ -0,0 +1,31 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY serverAdvanced.label "Gosodiadau Cyfrif Uwch">
+<!-- LOCALIZATION NOTE (serverDirectory.label): Do not translate "IMAP" -->
+<!ENTITY serverDirectory.label "Cyfeiriadur gweinydd IMAP:">
+<!ENTITY serverDirectory.accesskey "g">
+<!ENTITY usingSubscription.label "Dangos ffolderi tanysgrifiwyd iddynt">
+<!ENTITY usingSubscription.accesskey "t">
+<!ENTITY dualUseFolders.label "Mae'r gweinydd yn cynnal ffolderi sy'n cynnwys is-ffolderi a negeseuon">
+<!ENTITY dualUseFolders.accesskey "f">
+<!ENTITY maximumConnectionsNumber.label "Uchafswm cysylltiadau gweinydd i'r storfa">
+<!ENTITY maximumConnectionsNumber.accesskey "U">
+<!-- LOCALIZATION NOTE (namespaceDesc.label): Do not translate "IMAP" -->
+<!ENTITY namespaceDesc.label "Mae'r dewisiadau yn pennu bwlchenw ar eich gweinydd IMAP">
+<!ENTITY personalNamespace.label "Bwlchenw personol:">
+<!ENTITY personalNamespace.accesskey "B">
+<!ENTITY publicNamespace.label "Cyhoeddus (rhannu):">
+<!ENTITY publicNamespace.accesskey "y">
+<!ENTITY otherUsersNamespace.label "Defnyddwyr Eraill:">
+<!ENTITY otherUsersNamespace.accesskey "D">
+<!ENTITY overrideNamespaces.label "Caniatáu i'r gweinydd i wrth-wneud y bylchau enw">
+<!ENTITY overrideNamespaces.accesskey "C">
+<!ENTITY pop3DeferringDesc.label "Wrth lwytho e-bost i lawr o weinydd y cyfrif, defnyddiwch y ffolder ganlynol i gadw'r negeseuon newydd:" >
+<!ENTITY accountInbox.label "Blwch Derbyn y cyfrif hwn">
+<!ENTITY accountInbox.accesskey "c">
+<!ENTITY deferToServer.label "Blwch Derbyn cyfrif gwahanol">
+<!ENTITY deferToServer.accesskey "g">
+<!ENTITY deferGetNewMail.label "Cynnwys y gweinydd hwn wrth estyn e-byst newydd">
+<!ENTITY deferGetNewMail.accesskey "y">
diff --git a/l10n-cy/mail/chrome/messenger/am-server-top.dtd b/l10n-cy/mail/chrome/messenger/am-server-top.dtd
new file mode 100644
index 0000000000..6c4a69823e
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-server-top.dtd
@@ -0,0 +1,89 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY messageStorage.label "Storfa Negeseuon">
+<!ENTITY securitySettings.label "Gosodiadau Diogelwch">
+<!ENTITY serverSettings.label "Gosodiadau'r Gweinydd">
+<!ENTITY serverType.label "Math o Weinydd:">
+<!ENTITY serverName.label "Enw'r Gweinydd:">
+<!ENTITY serverName.accesskey "G">
+<!ENTITY userName.label "Enw Defnyddiwr:">
+<!ENTITY userName.accesskey "D">
+<!ENTITY port.label "Porth:">
+<!ENTITY port.accesskey "P">
+<!ENTITY serverPortDefault.label "Rhagosodiad:">
+<!-- LOCALIZATION NOTE (biffStart.label) : translate below 2 line with grammar dependency
+        For example, in Japanese cases:
+                biffStart.label "every"
+                biffEnd.label   "minutes for new messages Check"
+-->
+<!ENTITY biffStart.label "Gwirio am negeseuon newydd bob ">
+<!ENTITY biffStart.accesskey "w">
+<!ENTITY biffEnd.label "munud">
+<!ENTITY useIdleNotifications.label "Caniatáu hysbysiadau gweinydd di-oed wrth i negeseuon newydd gyrraedd">
+<!ENTITY useIdleNotifications.accesskey "a">
+<!ENTITY connectionSecurity.label "Diogelwch y cysylltiad:">
+<!ENTITY connectionSecurity.accesskey "D">
+<!ENTITY connectionSecurityType-0.label "Dim">
+<!ENTITY connectionSecurityType-1.label "STARTTLS, os ar gael">
+<!ENTITY connectionSecurityType-2.label "STARTTLS">
+<!ENTITY connectionSecurityType-3.label "SSL/TLS">
+<!ENTITY authMethod.label "Dull dilysu:">
+<!ENTITY authMethod.accesskey "u">
+<!ENTITY leaveOnServer.label "Gadael negeseuon ar y gweinydd">
+<!ENTITY leaveOnServer.accesskey "a">
+<!ENTITY headersOnly.label "Estyn penynnau'n unig">
+<!ENTITY headersOnly.accesskey "p">
+<!ENTITY deleteByAgeFromServer.label "Ar y mwyaf">
+<!ENTITY deleteByAgeFromServer.accesskey "m">
+<!ENTITY daysEnd.label "diwrnod">
+<!ENTITY deleteOnServer2.label "Nes i mi eu dileu">
+<!ENTITY deleteOnServer2.accesskey "d">
+<!ENTITY downloadOnBiff.label "Llwytho i lawr negeseuon newydd yn awtomatig">
+<!ENTITY downloadOnBiff.accesskey "a">
+<!ENTITY deleteMessagePrefix.label "Pan fyddaf yn dileu neges:">
+<!ENTITY modelMoveToTrash.label "Ei symud i'r ffolder yma:">
+<!ENTITY modelMoveToTrash.accesskey "y">
+<!ENTITY modelMarkDeleted.label "Marcio fel ei fod wedi'i ddileu">
+<!ENTITY modelMarkDeleted.accesskey "M">
+<!ENTITY modelDeleteImmediately.label "Diddymu'n syth">
+<!ENTITY modelDeleteImmediately.accesskey "i">
+<!-- LOCALIZATION NOTE (expungeOnExit.label) : do not translate two of "&quot;" in below line -->
+<!ENTITY expungeOnExit.label "Glanhau&apos;r (&quot;Expunge&quot;) Blwch Derbyn wrth Adael">
+<!ENTITY expungeOnExit.accesskey "G">
+<!ENTITY emptyTrashOnExit.label "Gwagio'r Sbwriel wrth Adael">
+<!ENTITY emptyTrashOnExit.accesskey "A">
+<!ENTITY loginAtStartup.label "Gwirio am negeseuon newydd wrth gychwyn">
+<!ENTITY loginAtStartup.accesskey "w">
+<!-- LOCALIZATION NOTE (maxMessagesStart.label) : translate below 2 lines with grammar dependency
+    maxMessengerStart.label will be followed by maxMessagesEnd.label with the number
+    of messages between them
+-->
+<!ENTITY maxMessagesStart.label "Gofyn cyn llwytho i lawr mwy na">
+<!ENTITY maxMessagesStart.accesskey "o">
+<!-- LOCALIZATION NOTE (maxMessagesEnd.label) : see note for maxMessagesStart.label -->
+<!ENTITY maxMessagesEnd.label "neges">
+<!ENTITY alwaysAuthenticate.label "Gofyn bob tro am ddilysiad wrth gysylltu â'r gweinydd hwn">
+<!ENTITY alwaysAuthenticate.accesskey "b">
+<!ENTITY newsrcFilePath1.label "Ffeil News.rc:">
+<!ENTITY newsrcPicker1.label "Dewis Ffeil News.rc">
+<!ENTITY abbreviate.label "Dangos enwau'r grŵp newyddion yn y paen Ffolder E-bost, fel:">
+<!ENTITY abbreviateOn.label "Enwau llawn (e.e, 'netscape.public.mozilla.mail-news')">
+<!ENTITY abbreviateOff.label "Enwau byr (e.e. 'n.p.m.mail-news')">
+<!ENTITY advancedButton.label "Uwch…">
+<!ENTITY advancedButton.accesskey "U">
+<!ENTITY serverDefaultCharset2.label "Amgodiad Testun Rhagosodedig:">
+<!ENTITY localPath1.label "Cyfeiriadur Lleol:">
+<!ENTITY localFolderPicker.label "Dewis Cyfeiriadur Lleol">
+<!ENTITY browseFolder.label "Pori…">
+<!ENTITY browseFolder.accesskey "P">
+<!ENTITY browseNewsrc.label "Pori…">
+<!ENTITY browseNewsrc.accesskey "o">
+
+<!ENTITY accountTitle.label "Gosodiadau Cyfrif">
+<!ENTITY accountSettingsDesc.label "Mae hwn yn gyfrif arbennig.  Nid oes hunaniaethau wedi'u cysylltu ag ef.">
+<!ENTITY storeType.label "Math o Storio Negeseuon:">
+<!ENTITY storeType.accesskey "S">
+<!ENTITY mboxStore2.label "Ffeil i'r ffolder (mbox)">
+<!ENTITY maildirStore.label "Ffeil y neges (maildir)">
diff --git a/l10n-cy/mail/chrome/messenger/am-serverwithnoidentities.dtd b/l10n-cy/mail/chrome/messenger/am-serverwithnoidentities.dtd
new file mode 100644
index 0000000000..af82c6f129
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-serverwithnoidentities.dtd
@@ -0,0 +1,6 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY accountName.label "Enw Cyfrif:">
+<!ENTITY accountName.accesskey "C">
diff --git a/l10n-cy/mail/chrome/messenger/am-smime.dtd b/l10n-cy/mail/chrome/messenger/am-smime.dtd
new file mode 100644
index 0000000000..a69f3598f8
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-smime.dtd
@@ -0,0 +1,47 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY e2eTitle.label "Amgryptio Pen-i-Ben">
+<!ENTITY e2eLearnMore.label "Dysgu rhagor">
+
+<!ENTITY e2eEnc.description "Heb amgryptio pen-i-ben mae cynnwys negeseuon yn hawdd eu hamlygu i'ch darparwr e-bost ac i wyliadwriaeth dorfol.">
+
+<!ENTITY e2eTechPref.description "Y dewis o dechnoleg amgryptio:">
+
+<!ENTITY encryptionCert2.message "Tystysgrif bersonol ar gyfer amgryptio:">
+<!ENTITY digitalSign.certificate.button "Dewis…">
+<!ENTITY digitalSign.certificate.accesskey "S">
+<!ENTITY digitalSign.certificate_clear.button "Clirio">
+<!ENTITY digitalSign.certificate_clear.accesskey "C">
+<!ENTITY encryption.certificate.button "Dewis…">
+<!ENTITY encryption.certificate.accesskey "w">
+<!ENTITY encryption.certificate_clear.button "Clirio">
+<!ENTITY encryption.certificate_clear.accesskey "l">
+<!ENTITY signingGroupTitle.label "Llofnodi Digidol">
+
+<!ENTITY signingCert2.message "Tystysgrif bersonol ar gyfer amgryptio:">
+
+<!ENTITY sendingDefaults.label "Gosodiadau rhagosodedig ar gyfer anfon negeseuon">
+
+<!ENTITY technologyAutomatic.label "Dewis yn awtomatig ar sail yr allweddi neu'r tystysgrifau sydd ar gael">
+
+<!ENTITY certificates2.label "S/MIME">
+<!ENTITY manageCerts3.label "Rheoli Tystysgrifau S/MIME">
+<!ENTITY manageCerts3.accesskey "M">
+<!ENTITY manageDevices2.label "Dyfeisiau Diogelwch S/MIME">
+<!ENTITY manageDevices2.accesskey "y">
+
+<!ENTITY technologySMIME.label "Dewis S/MIME">
+<!ENTITY technologyOpenPGP.label "Dewis OpenPGP">
+
+<!ENTITY openpgpKeys.label "OpenPGP">
+
+<!-- Strings for the cert picker dialog -->
+<!ENTITY certPicker.title "Dewis Tystysgrif">
+<!ENTITY certPicker.info  "Tystysgrif:">
+<!ENTITY certPicker.detailsLabel "Manylion y dystysgrif hon:">
+
+<!ENTITY openpgpKey.message "Allwedd bersonol ar gyfer amgryptio a llofnodi digidol:">
+<!ENTITY openpgpKey.button "Gosod Allwedd Bersonol…">
+<!ENTITY openpgpKey.accesskey "G">
diff --git a/l10n-cy/mail/chrome/messenger/am-smime.properties b/l10n-cy/mail/chrome/messenger/am-smime.properties
new file mode 100644
index 0000000000..27fd773de7
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/am-smime.properties
@@ -0,0 +1,39 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+## S/MIME error strings.
+## Note to localization: %S is a placeholder
+NoSenderSigningCert=Rydych wedi nodi y dylai'r neges fod wedi'i llofnodi'n ddigidol, ond un ai methodd y rhaglen a chanfod y dystysgrif llofnodwyd ac a enwyd yn Gosodiadau eich E-bost a Grŵp newyddion neu mae'r dystysgrif wedi dod i ben.
+NoSenderEncryptionCert=Rydych wedi pennu amgryptiad ar gyfer y neges, ond un ai methodd y rhaglen ganfod y dystysgrif amgryptio nodwyd yn eich Gosodiadau Cyfrif E-bost a Grŵp Newyddion.
+MissingRecipientEncryptionCert=Rydych wedi pennu amgryptiad ar gyfer y neges, ond methodd y rhaglen â chanfod tystysgrif amgryptio ar gyfer %S.
+ErrorEncryptMail=Methu amgryptio'r neges. Gwiriwch fod gennych dystysgrif e-bost dilys ar gyfer pob derbynnydd. Gwiriwch fod y tystysgrifau enwyd yn Gosodiadau Cyfrifon E-bost a Grwpiau Newyddion ar gyfer y cyfrif e-bost yn ddilys a dibynadwy ar gyfer e-bost.
+ErrorCanNotSignMail=Methu llofnodi'r neges. Gwiriwch fod y tystysgrifau enwyd yn Gosodiadau Cyfrifon E-bost a Grwpiau Newyddion ar gyfer y cyfrif e-bost yn ddilys a dibynadwy ar gyfer e-bost.
+
+NoSigningCert=Nid yw'r Rheolwr Tystysgrifau wedi gallu canfod tystysgrif ddilys i'w ddefnyddio i lofnodi eich negeseuon.
+NoSigningCertForThisAddress=Nid yw'r Rheolwr Tystysgrifau wedi gallu canfod tystysgrif ddilys i'w ddefnyddio i lofnodi eich negeseuon gyda cyfeiriad <%S>.
+NoEncryptionCert=Nid yw'r Rheolwr Tystysgrifau wedi gallu canfod tystysgrif ddilys i bobl eraill ddefnyddio i anfon negeseuon e-bost wedi'u hamgryptio.
+NoEncryptionCertForThisAddress=Nid yw'r Rheolwr Tystysgrifau wedi gallu canfod tystysgrif ddilys i bobl eraill ddefnyddio i anfon negeseuon e-bost wedi'u hamgryptio i'r cyfeiriad <%S>.
+
+encryption_needCertWantSame=Dylech hefyd bennu tystysgrif ar gyfer pobl eraill i'w defnyddio pan fyddant yn anfon negeseuon wedi'u hamgryptio atoch. Hoffech chi ddefnyddio'r un dystysgrif i amgryptio a dadgriptio negeseuon anfonwyd atoch?
+encryption_wantSame=Ydych chi am ddefnyddio'r un dystysgrif i amgryptio a dadgriptio negeseuon anfonwyd atoch?
+encryption_needCertWantToSelect=Dylech bennu tystysgrif ar gyfer pobl eraill pan fyddwch yn anfon neges wedi'i hamgryptio atoch. Hoffech chi ffurfweddu tystysgrif amgryptio?
+signing_needCertWantSame=Dylech hefyd bennu tystysgrif i'w defnyddio ar gyfer llofnodi eich negeseuon yn ddigidol. Hoffech chi ddefnyddio'r un dystysgrif i lofnodi eich negeseuon yn ddigidol?
+signing_wantSame=Hoffech chi ddefnyddio'r un dystysgrif i lofnodi eich negeseuon yn ddigidol?
+signing_needCertWantToSelect=Dylech hefyd bennu tystysgrif i'w ddefnyddio ar gyfer llofnodi eich negeseuon yn ddigidol. Hoffech chi ffurfweddu tystysgrif ar gyfer llofnodi negeseuon yn ddigidol?
+
+## Strings used by nsMsgComposeSecure
+mime_smimeEncryptedContentDesc=Neges Amgryptiedig S/MIME
+mime_smimeSignatureContentDesc=Llofnod Cryptograffeg S/MIME
+
+## Strings used by the cert picker.
+CertInfoIssuedFor=Cyhoeddwyd i:
+CertInfoIssuedBy=Cyhoeddwyd gan:
+CertInfoValid=Dilys
+CertInfoFrom=oddi wrth
+CertInfoTo=at
+CertInfoPurposes=Pwrpas
+CertInfoEmail=E-bost
+CertInfoStoredIn=Storiwyd yn:
+NicknameExpired=(daeth i ben)
+NicknameNotYetValid=(nid yn ddilys eto)
diff --git a/l10n-cy/mail/chrome/messenger/appUpdate.properties b/l10n-cy/mail/chrome/messenger/appUpdate.properties
new file mode 100644
index 0000000000..ca3d623504
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/appUpdate.properties
@@ -0,0 +1,40 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (updateAvailableTitle): %S will be replaced with brandShortName
+updateAvailableTitle=Mae diweddariad %S newydd ar gael.
+# LOCALIZATION NOTE (updateAvailableMessage): %S will be replaced with brandShortName
+updateAvailableMessage=Diweddarwch eich %S am y cyflymder a'r preifatrwydd diweddaraf.
+updateAvailablePrimaryButtonLabel=Llwytho'r Diweddariad i Lawr
+updateAvailablePrimaryButtonAccessKey=D
+updateAvailableSecondaryButtonLabel=Nid Nawr
+updateAvailableSecondaryButtonAccessKey=N
+
+# LOCALIZATION NOTE (updateManualTitle): %S will be replaced with brandShortName
+updateManualTitle=Nid yw %S yn gallu diweddaru i'r fersiwn diweddaraf.
+# LOCALIZATION NOTE (updateManualMessage): %S will be replaced with brandShortName
+updateManualMessage=Llwythwch gopi newydd o %S i lawr ac mi wnawn ni eich helpu i'w gosod.
+# LOCALIZATION NOTE (updateManualPrimaryButtonLabel): %S will be replaced with brandShortName
+updateManualPrimaryButtonLabel=Llwytho i Lawr %S
+updateManualPrimaryButtonAccessKey=L
+updateManualSecondaryButtonLabel=Nid Nawr
+updateManualSecondaryButtonAccessKey=N
+
+# LOCALIZATION NOTE (updateUnsupportedTitle): %S will be replaced with brandShortName
+updateUnsupportedTitle=Nid yw %S yn gallu diweddaru i'r fersiwn diweddaraf.
+# LOCALIZATION NOTE (updateUnsupportedMessage): %S will be replaced with brandShortName
+updateUnsupportedMessage=Nid yw'r fersiwn diweddaraf o %S yn cael ei gynnal gan eich system.
+updateUnsupportedPrimaryButtonLabel=Dysgu rhagor
+updateUnsupportedPrimaryButtonAccessKey=D
+updateUnsupportedSecondaryButtonLabel=Cau
+updateUnsupportedSecondaryButtonAccessKey=C
+
+# LOCALIZATION NOTE (updateRestartTitle): %S will be replaced with brandShortName
+updateRestartTitle=Ailgychwyn i ddiweddaru %S.
+# LOCALIZATION NOTE (updateRestartMessage): %S will be replaced with brandShortName
+updateRestartMessage=Ar ôl ail gychwyn cyflym, bydd %S yn adfer eich holl dabiau a'r ffenestri sydd ar agor.
+updateRestartPrimaryButtonLabel=Ail gychwyn
+updateRestartPrimaryButtonAccessKey=A
+updateRestartSecondaryButtonLabel=Nid Nawr
+updateRestartSecondaryButtonAccessKey=N
diff --git a/l10n-cy/mail/chrome/messenger/appleMailImportMsgs.properties b/l10n-cy/mail/chrome/messenger/appleMailImportMsgs.properties
new file mode 100644
index 0000000000..b47b5aaed7
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/appleMailImportMsgs.properties
@@ -0,0 +1,21 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Short name of import module
+ApplemailImportName=Apple Mail
+
+# Description of import module
+ApplemailImportDescription=Mewnforio E-bost Lleol o Mac OS X Mail
+
+# Success Message
+# LOCALIZATION NOTE(ApplemailImportMailboxSuccess): Do not translate the word "%S" below.
+ApplemailImportMailboxSuccess=Mewnforiwyd negeseuon lleol yn llwyddiannus o %S
+
+# Error Message
+ApplemailImportMailboxBadparam=Digwyddodd gwall mewnol. Methodd mewnforio. Ceisiwch fewnforio eto.
+
+# Error message
+# LOCALIZATION NOTE(ApplemailImportMailboxConverterror): Do not translate the word "%S" below.
+ApplemailImportMailboxConverterror=Digwyddodd gwall wrth fewnforio negeseuon o %S. Nid yw'r negeseuon wedi'u mewnforio.
+
diff --git a/l10n-cy/mail/chrome/messenger/baseMenuOverlay.dtd b/l10n-cy/mail/chrome/messenger/baseMenuOverlay.dtd
new file mode 100644
index 0000000000..cd516d5f2d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/baseMenuOverlay.dtd
@@ -0,0 +1,35 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- Help Menu -->
+<!ENTITY helpMenu.label "Cymorth">
+<!ENTITY helpMenu.accesskey "C">
+<!-- LOCALIZATION NOTE some localizations of Windows use "?"
+                       for the help button in the menubar but Gnome does not.   -->
+<!ENTITY helpMenuWin.label "Cymorth">
+<!ENTITY helpMenuWin.accesskey "y">
+<!ENTITY aboutProduct2.label "Ynghylch &brandShorterName;">
+<!ENTITY aboutProduct2.accesskey "Y">
+
+<!ENTITY productHelp.label "Cymorth &brandShortName;">
+<!ENTITY productHelp.accesskey "C">
+
+<!ENTITY productHelp.commandkey "VK_F1">
+<!ENTITY productHelpMac.commandkey "?">
+<!ENTITY productHelpMac.modifiers "accel">
+
+<!ENTITY helpKeyboardShortcuts.label "Llwybrau Byr Bysellfwrdd">
+<!ENTITY helpKeyboardShortcuts.accesskey "L">
+
+<!ENTITY helpFeedbackPage.label "Cyflwyno Adborth…">
+<!ENTITY helpFeedbackPage.accesskey "A">
+
+<!ENTITY helpShowTour2.label "Cyflwyno &brandShorterName;">
+<!ENTITY helpShowTour2.accesskey "C">
+
+<!ENTITY helpGetInvolvedPage.label "Ymunwch">
+<!ENTITY helpGetInvolvedPage.accesskey "Y">
+
+<!ENTITY helpDonationsPage.label "Gwnewch Rodd">
+<!ENTITY helpDonationsPage.accesskey "R">
diff --git a/l10n-cy/mail/chrome/messenger/beckyImportMsgs.properties b/l10n-cy/mail/chrome/messenger/beckyImportMsgs.properties
new file mode 100644
index 0000000000..4c22395c01
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/beckyImportMsgs.properties
@@ -0,0 +1,19 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+# The following are used by the becky import code to display status/error
+# and informational messages
+
+# Short name of import module
+BeckyImportName=Becky! Internet Mail
+
+# Description of import module
+BeckyImportDescription=Mewnforion E-byst Lleol o Becky! Internet Mail
+
+# Success Message
+# LOCALIZATION NOTE : Do not translate the word "%S" below.
+# The variable %S will contain the name of the Mailbox
+BeckyImportMailboxSuccess=Mewnforiwyd negeseuon lleol yn llwyddiannus o %S.
+
+BeckyImportAddressSuccess=Mewnforiwyd y llyfr cyfeiriadau
diff --git a/l10n-cy/mail/chrome/messenger/charsetTitles.properties b/l10n-cy/mail/chrome/messenger/charsetTitles.properties
new file mode 100644
index 0000000000..d5d60eda3d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/charsetTitles.properties
@@ -0,0 +1,84 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+## Rule of this file:
+## 1. key should always be in lower case ascii so we can do case insensitive
+##    comparison in the code faster.
+
+## Format of this file:
+## charset_name.title = a_title  -  specifies the human readable title for 
+## this charset
+
+## Format of this file:
+## charset_name.title = a_title  -  specifies the human readable title for
+## this charset
+
+iso-8859-1.title    = Gorllewinol (ISO-8859-1)
+iso-8859-2.title    = Canol Ewrop (ISO-8859-2)
+iso-8859-3.title    = De Ewropeaidd (ISO-8859-3)
+iso-8859-4.title    = Baltig (ISO-8859-4)
+iso-8859-10.title   = Nordaidd (ISO-8859-10)
+iso-8859-13.title   = Baltig (ISO-8859-13)
+iso-8859-14.title   = Celtaidd (ISO-8859-14)
+iso-8859-15.title   = Gorllewinol (ISO-8859-15)
+iso-8859-16.title   = Rwmaneg (ISO-8859-16)
+windows-1250.title  = Canol Ewrop (Windows-1250)
+windows-1252.title  = Gorllewinol (Windows-1252)
+windows-1254.title  = Twrceg (Windows-1254)
+windows-1257.title  = Baltig (Windows-1257)
+macintosh.title         = Gorllewinol (MacRoman)
+x-mac-ce.title          = Canol Ewrop (MacCE)
+x-mac-turkish.title     = Twrceg (MacTurkish)
+x-mac-croatian.title    = Croateg (MacCroatian)
+x-mac-romanian.title    = Rwmanaidd (MacRomanian)
+x-mac-icelandic.title   = Islandeg (MacIcelandic)
+iso-2022-jp.title = Japanëeg (ISO-2022-JP)
+shift_jis.title = Japanëeg (Shift-JIS)
+euc-jp.title = Japanëeg (EUC-JP)
+big5.title = Tsieinëeg Traddodiadol (Big5)
+big5-hkscs.title = Tsieinëeg Traddodiadol (Big5-HK_SCS)
+gb2312.title = Tsieinëeg Symledig (GB2312)
+gbk.title = Tsieinëeg Symledig (GBK)
+euc-kr.title = Corëeg (EUC-KR)
+utf-7.title = Unicode (UTF-7)
+utf-8.title = Unicode (UTF-8)
+utf-16.title = Unicode (UTF-16)
+utf-16le.title = Unicode (UTF-16LE)
+utf-16be.title = Unicode (UTF-16BE)
+iso-8859-5.title = Cyrilig (ISO-8859-5)
+windows-1251.title = Syrilig (Windows-1251)
+x-mac-cyrillic.title = Cyrilig (MacCyrillic)
+x-mac-ukrainian.title = Cyrilig/Wcraneg(MacUkrainian)
+koi8-r.title = Cyrilig (KOI8-R)
+koi8-u.title = Cyrilig/Wcraneg (KOI8-U)
+iso-8859-7.title = Groeg (ISO-8859-7)
+windows-1253.title = Groeg (Windows-1253)
+x-mac-greek.title = Groeg (MacGreek)
+windows-1258.title = Fietnameg (Windows-1258)
+windows-874.title = Thai (Windows-874)
+iso-8859-6.title = Arabeg (ISO-8859-6)
+iso-8859-8.title = Hebraeg Gweledol (ISO-8859-8)
+iso-8859-8-i.title = Hebraeg (ISO-8859-8-I)
+windows-1255.title = Hebraeg (Windows-1255)
+windows-1256.title = Arabeg (Windows-1256)
+x-user-defined.title = Defnyddiwr Diffiniedig
+ibm866.title = Cyrillig/Rwsia (CP-866)
+gb18030.title = Tsieinëeg Symliedig (_GB18030)
+x-mac-arabic.title = Arabeg (MacArabic)
+x-mac-farsi.title = Ffarsi (MacFarsi)
+x-mac-hebrew.title = Hebraeg (MacHebrew)
+x-mac-devanagari.title = Hindi (MacDevanagari)
+x-mac-gujarati.title = Gujurati (MacGujurati)
+x-mac-gurmukhi.title = Gurmukhi (MacGurmukhi)
+
+chardet.off.title                           = (Diffodd)
+chardet.universal_charset_detector.title    = Cyffredinol
+chardet.ja_parallel_state_machine.title     = Siapanëeg
+chardet.ko_parallel_state_machine.title     = Corëeg
+chardet.zhtw_parallel_state_machine.title   = Tsieinëeg Traddodiadol
+chardet.zhcn_parallel_state_machine.title   = Tsieinëeg Syml
+chardet.zh_parallel_state_machine.title     = Tseinëeg
+chardet.cjk_parallel_state_machine.title    = Dwyrain Asia
+chardet.ruprob.title                        = Rwsiaidd
+chardet.ukprob.title                        = Wcranaidd
diff --git a/l10n-cy/mail/chrome/messenger/chat.dtd b/l10n-cy/mail/chrome/messenger/chat.dtd
new file mode 100644
index 0000000000..24d534cd34
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/chat.dtd
@@ -0,0 +1,44 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY onlineContactsHeader.label    "Cysylltiadau Ar-lein">
+<!ENTITY offlineContactsHeader.label   "Cysylltiadau All-lein">
+<!ENTITY conversationsHeader.label     "Sgyrsiau">
+<!ENTITY searchResultConversation.label "Canlyniadau chwilio">
+<!ENTITY chat.noConv.title             "Bydd trafodaethau'n cael eu dangos yn fan hyn.">
+<!ENTITY chat.noConv.description       "Defnyddiwch y rhestr cysylltiadau yn y panel ar y chwith er mwyn cychwyn trafodaeth.">
+<!ENTITY chat.noPreviousConv.description       "Nid oes gan &brandShortName; unrhyw drafodaethau blaenorol wedi eu cadw gyda'r cysylltiad yma.">
+<!ENTITY chat.noAccount.title             "Nid ydych wedi creu cyfrif sgwrsio eto.">
+<!ENTITY chat.noAccount.description       "Gadewch i &brandShortName; eich tywys drwy'r broses o greu cyfrif sgwrsio.">
+<!ENTITY chat.accountWizard.button       "Cychwyn arni">
+<!ENTITY chat.noConnectedAccount.title             "Nid yw eich cyfrifon sgwrsio wedi'u cysylltu.">
+<!ENTITY chat.noConnectedAccount.description       "Mae modd eu cysylltu drwy'r ddeialog 'Statws sgwrsio':">
+<!ENTITY chat.showAccountManager.button       "Dangos statws sgwrsio">
+
+<!ENTITY chat.participants             "Cyfranogwyr:">
+<!ENTITY chat.previousConversations    "Sgyrsiau Blaenorol:">
+<!ENTITY chat.ongoingConversation      "Sgwrs gyfredol">
+
+<!ENTITY openConversationCmd.label     "Cychwyn Sgwrs">
+<!ENTITY openConversationCmd.accesskey "C">
+<!ENTITY closeConversationCmd.label    "Gorffen Sgwrs">
+<!ENTITY closeConversationCmd.accesskey "G">
+<!ENTITY aliasCmd.label                "Ailenwi">
+<!ENTITY aliasCmd.accesskey            "A">
+<!ENTITY deleteCmd.label               "Tynnu Cysylltiad">
+<!ENTITY deleteCmd.accesskey           "T">
+
+<!ENTITY openConversationButton.tooltip  "Cychwyn trafodaeth">
+<!ENTITY closeConversationButton.tooltip "Gorffen trafodaeth">
+
+<!ENTITY addBuddyButton.label          "Ychwanegu Cysylltiad">
+<!ENTITY joinChatButton.label          "Ymuno â Sgwrs">
+<!ENTITY chatAccountsButton.label      "Dangos Cyfrifon">
+
+<!ENTITY status.available          "Ar Gael">
+<!ENTITY status.unavailable        "Ddim ar Gael">
+<!ENTITY status.offline            "All-lein">
+
+<!ENTITY openLinkCmd.label            "Agor Dolen…">
+<!ENTITY openLinkCmd.accesskey        "D">
diff --git a/l10n-cy/mail/chrome/messenger/chat.properties b/l10n-cy/mail/chrome/messenger/chat.properties
new file mode 100644
index 0000000000..5afa6618ee
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/chat.properties
@@ -0,0 +1,110 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+chatTabTitle=Sgwrsio
+goBackToCurrentConversation.button=Nôl i'r drafodaeth gyfredol
+# LOCALIZATION NOTE (startAConversationWith.button):
+#  %S is replaced with the display name of a contact.
+startAConversationWith.button=Cychwyn trafodaeth gyda %S
+
+# LOCALIZATION NOTE (defaultGroup):
+#  this is used in the addBuddies dialog if the list of existing groups is empty
+defaultGroup=Cysylltiadau
+
+# LOCALIZATION NOTE (buddy.authRequest.label):
+# This string appears in a notification bar at the
+# top of the Contacts window when someone added the user to his/her
+# contact list, to request the permission from the user to share
+# status information with this potential new contact.
+# %S is replaced with the user name of the potential new contact.
+buddy.authRequest.label=Mae %S eisiau sgwrsio gyda chi
+buddy.authRequest.allow.label=Caniatáu
+buddy.authRequest.allow.accesskey=C
+buddy.authRequest.deny.label=Gwrthod
+buddy.authRequest.deny.accesskey=G
+
+## LOCALIZATION NOTE (buddy.verificationRequest):
+# Strings used in a notification bar at the top of the chat tab when someone
+# sends a verification request for end-to-end encryption keys.
+# %S is replaced with the display name of the user or, if this is to verify a
+# session of yourself, a string that identifies the session.
+buddy.verificationRequest.label=Mae %S eisiau gwirio hunaniaeth ei gilydd
+buddy.verificationRequest.allow.label=Cychwyn Gwirio
+buddy.verificationRequest.allow.accesskey=C
+buddy.verificationRequest.deny.label=Gwrthod
+buddy.verificationRequest.deny.accesskey=G
+
+# LOCALIZATION NOTE (buddy.deletePrompt.title):
+# %S here will be replaced by the alias (or username) of a buddy about
+# to be removed from the buddy list.
+buddy.deletePrompt.title=Dileu %S?
+
+# LOCALIZATION NOTE (buddy.deletePrompt.message):
+# %1$S will be replaced by the name of a buddy (either the alias
+# followed by the username between parenthesis if an alias is set, or
+# only the username otherwise).
+# %2$S will be the name of the protocol on which this buddy is removed
+# (for example: AIM, MSN, Google Talk).
+#
+# Please find a wording that will keep the username as close as
+# possible to the beginning of the string, because this is the
+# important information that an user should see when looking quickly
+# at this prompt.
+buddy.deletePrompt.message=Bydd %1$S yn cael ei dynnu'n barhaol o'ch rhestr ffrindiau %2$S os byddwch yn parhau.
+
+# LOCALIZATION NOTE (buddy.deletePrompt.displayName):
+# This is used to format the display name inserted in buddy.deletePrompt.message
+# %1$S is the alias, %2$S is the username.
+buddy.deletePrompt.displayName=%1$S (%2$S)
+
+# LOCALIZATION NOTE (buddy.deletePrompt.button):
+# the & symbol indicates the position of the character that should be
+# used as the accesskey for this button.
+buddy.deletePrompt.button=&Dileu
+
+displayNameEmptyText=Dangos Enw
+userIconFilePickerTitle=Dewis eicon newydd…
+
+# LOCALIZATION NOTE (chat.isTyping, chat.hasStoppedTyping):
+# The contact display name is displayed with a big font on a first
+# line and these two strings are displayed on a second line with a
+# smaller font. Please try to find a wording that make this look
+# almost like a sentence.
+chat.isTyping=yn teipio…
+chat.hasStoppedTyping=wedi stopio teipio.
+# LOCALIZATION NOTE (chat.contactIsTyping, chat.contactHasStoppedTyping):
+#  These strings are displayed in a tooltip when hovering the status type icon.
+#  %S is replaced with the display name of the contact.
+chat.contactIsTyping=Mae %S yn teipio.
+chat.contactHasStoppedTyping=Mae %S wedi stopio teipio.
+
+# LOCALIZATION NOTE (unknownCommand):
+# This is shown when an unknown command (/foo) is attempted. %S is the command.
+unknownCommand=Nid yw %S yn orchymyn sy'n cael ei chynnal. Teipiwch /help i weld y rhestr o orchmynion.
+
+#LOCALIZATION NOTE
+# These are special entries in the log tree for the corresponding days.
+log.today=Heddiw
+log.yesterday=Ddoe
+
+#LOCALIZATION NOTE
+# These are special groups in the log tree for the last 3-7 days and
+# the last 8-14 days.
+log.currentWeek=Wythnos hon
+log.previousWeek=Wythnos Diwethaf
+
+# LOCALIZATION NOTE (messagePreview):
+# This is the default message preview to be shown
+# when the user has chosen not to show any info in the notification about the
+# incoming message being notified.
+messagePreview=Neges Sgwrs Newydd
+
+#LOCALIZATION NOTE (bundledMessagePreview):  Semi-colon list of plural forms.
+# Used when multiple incoming messages from the same sender are bundled
+# into a single notification.
+# #1 is the number of incoming messages the user is being notified about. When #1
+# is greater than one, the plural form after the semicolon is used.
+# Do not translate %1$S, it is the message preview to be shown in the
+# notification, i.e. the first incoming message.
+bundledMessagePreview=%1$S… (a #1 neges ychwanegol);%1$S… (a #1 neges ychwanegol)
diff --git a/l10n-cy/mail/chrome/messenger/configEditorOverlay.dtd b/l10n-cy/mail/chrome/messenger/configEditorOverlay.dtd
new file mode 100644
index 0000000000..3d78799d68
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/configEditorOverlay.dtd
@@ -0,0 +1,5 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY closeCmd.key "W">
diff --git a/l10n-cy/mail/chrome/messenger/converterDialog.dtd b/l10n-cy/mail/chrome/messenger/converterDialog.dtd
new file mode 100644
index 0000000000..9ea79f5311
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/converterDialog.dtd
@@ -0,0 +1,11 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY converterDialog.title "Troswr Math Cadw Neges">
+<!ENTITY converterDialog.continueButton "Ymlaen">
+<!ENTITY converterDialog.cancelButton "Diddymu">
+<!ENTITY converterDialog.finishButton "Gorffen">
+<!ENTITY converterDialog.complete "Mae'r trosi wedi ei gwblhau. Bydd &brandShortName; nawr yn ail gychwyn.">
+<!ENTITY converterDialog.error "Methodd y trosi.">
+
diff --git a/l10n-cy/mail/chrome/messenger/converterDialog.properties b/l10n-cy/mail/chrome/messenger/converterDialog.properties
new file mode 100644
index 0000000000..9bba0f3c62
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/converterDialog.properties
@@ -0,0 +1,41 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (converterDialog.warning):
+# %1$S will be replaced by the name of the account which is going to be converted.
+# %2$S will be replaced by the format into which the account will be converted.
+# %3$S will be replaced by $BrandShortName.
+converterDialog.warning=Bydd y negeseuon yng nghyfrif %1$S nawr yn cael eu trosi i fformat %2$S. Bydd %3$S yn ailgychwyn wedi i'r trosi gael ei gwblhau.
+
+# LOCALIZATION NOTE (converterDialog.message):
+# %1$S will be replaced by the name of the account which is being converted.
+# %2$S will be replaced by the format into which the account will be converted.
+converterDialog.message=Trosi cyfrif %1$S i %2$S…
+
+# LOCALIZATION NOTE (converterDialog.warningForDeferredAccount):
+# %1$S will be replaced by the name of the deferred account for which migration is initiated by the user.
+# %2$S will be replaced by the name of the account to which the deferred account is deferred ie the name of the deferred-to account.
+# %3$S will be replaced by the name of the deferred-to account.
+# %4$S will be replaced by a comma separated list of names of accounts which are deferred to the deferred-to account.
+# %5$S will be replaced by a comma separated list of names of accounts which are going to get converted.
+# %6$S will be replaced by the format into which the accounts will be converted.
+# %7$S will be replaced by $BrandShortName.
+converterDialog.warningForDeferredAccount=Mae %1$S wedi ei drosi i %2$S. Cyfrifon wedi eu trosi i %3$S: %4$S. Bydd y negeseuon yn nghyfrifon %5$S yn cael eu trosi i fformat %6$S. Bydd %7$S yn ailgychwyn wedi i'r trosi gael ei gwblhau.
+
+# LOCALIZATION NOTE (converterDialog.warningForDeferredToAccount):
+# %1$S will be replaced by the name of the deferred-to account for which migration is initiated by the user and to which other accounts are deferred.
+# %2$S will be replaced by a comma separated list of names of accounts which are deferred to the deferred-to account.
+# %3$S will be replaced by a comma separated list of names of accounts which are going to get converted.
+# %4$S will be replaced by the format into which the accounts will be converted.
+# %5$S will be replaced by $BrandShortName.
+converterDialog.warningForDeferredToAccount=Cyfrifon wedi eu trosi i %1$S: %2$S. Bydd y negeseuon yng nghyfrif %3$S nawr yn cael eu trosi i fformat %4$S. Bydd %5$S yn ailgychwyn wedi i'r trosi gael ei gwblhau.
+
+# LOCALIZATION NOTE (converterDialog.messageForDeferredAccount):
+# %1$S will be replaced by a comma separated list of names of accounts which are being converted.
+# %2$S will be replaced by the format into which the accounts will be converted.
+converterDialog.messageForDeferredAccount=Trosi cyfrifon %1$S i %2$S…
+
+# LOCALIZATION NOTE (converterDialog.percentDone):
+# %1$S will be replaced by the percentage of conversion that is complete.
+converterDialog.percentDone=%1$S%% wedi ei gwblhau
diff --git a/l10n-cy/mail/chrome/messenger/custom.properties b/l10n-cy/mail/chrome/messenger/custom.properties
new file mode 100644
index 0000000000..d4ca87a701
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/custom.properties
@@ -0,0 +1,5 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+colonInHeaderName=Mae'r pennyn rydych wedi ei roi yn cynnwys nodau annilys, megis ':', nod anargraffadwy, nod nad yw'n ascii, neu nod ascii wyth did. Tynnwch y nod annilys a cheisiwch eto.
diff --git a/l10n-cy/mail/chrome/messenger/customizeToolbar.dtd b/l10n-cy/mail/chrome/messenger/customizeToolbar.dtd
new file mode 100644
index 0000000000..7a5e7dc048
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/customizeToolbar.dtd
@@ -0,0 +1,18 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY dialog.title             "Cyfaddasu'r Bar Offer">
+<!ENTITY dialog.dimensions        "width: 92ch; height: 36em;">
+<!ENTITY instructions.description "Gallwch ychwanegu neu dynnu eitemau drwy lusgo i neu oddi wrth y barau offer.">
+<!ENTITY show.label               "Dangos:">
+<!ENTITY iconsAndText.label       "Eiconau a Thestun">
+<!ENTITY icons.label              "Eiconau">
+<!ENTITY text.label               "Testun">
+<!ENTITY iconsBesideText.label    "Eiconau gerllaw Testun">
+<!ENTITY useSmallIcons.label      "Defnyddio Eiconau Bach">
+<!ENTITY restoreDefaultSet.label  "Adfer y Set Ragosodedig">
+<!ENTITY showTitlebar2.label      "Bar Teitl">
+<!ENTITY extraDragSpace2.label    "Gofod Llusgo">
+<!ENTITY saveChanges.label        "Gorffen">
+<!ENTITY undoChanges.label        "Dadwneud Newidiadau">
diff --git a/l10n-cy/mail/chrome/messenger/customizeToolbar.properties b/l10n-cy/mail/chrome/messenger/customizeToolbar.properties
new file mode 100644
index 0000000000..3b1e6eafed
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/customizeToolbar.properties
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+enterToolbarTitle=Bar Offer Newydd
+enterToolbarName=Rhoi enw i'r bar offer hwn:
+enterToolbarDup=Mae eisoes far offer gyda'r enw “%S”. Rhowch enw arall.
+enterToolbarBlank=Rhaid cynnig enw i greu bar offer newydd.
+separatorTitle=Ymwahanydd
+springTitle=Bwlch Hyblyg
+spacerTitle=Bwlch
diff --git a/l10n-cy/mail/chrome/messenger/devtools/dbgserver.dtd b/l10n-cy/mail/chrome/messenger/devtools/dbgserver.dtd
new file mode 100644
index 0000000000..5bb77eb935
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/devtools/dbgserver.dtd
@@ -0,0 +1,8 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY options.title "Dewisiadau Offer Datblygwyr">
+<!ENTITY options.status.label "Statws:">
+<!ENTITY options.port.label "Porth:">
+<!ENTITY options.forcelocal.label "Caniatáu cysylltiadau o gyfrifiaduron eraill">
diff --git a/l10n-cy/mail/chrome/messenger/devtools/dbgserver.properties b/l10n-cy/mail/chrome/messenger/devtools/dbgserver.properties
new file mode 100644
index 0000000000..7fa51e5fbb
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/devtools/dbgserver.properties
@@ -0,0 +1,15 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+options.stop.label=Atal y Gweinydd Offer Datblygwyr
+options.start.label=Cychwyn y Gweinydd Offer Datblygwyr
+
+options.connected.label=#1 Client wedi'i Gysylltu;#1 Client wedi eu Cysylltu
+options.connected.tooltip=Mae gweinydd offer datblygwyr yn rhedeg ac mae cleientiaid wedi eu cysylltu.
+options.listening.label=Gwrando
+options.listening.tooltip=Mae'r gweinydd offer datblygwyr yn rhedeg ac yn aros am gysylltiadau.
+options.idle.label=Ddim yn Rhedeg
+options.idle.tooltip=Nid yw'r gweinydd offer datblygwyr yn rhedeg. Mae modd ei gychwyn o fan hyn.
+options.unsupported.label=Heb ei gynnal
+options.unsupported.tooltip=Bu gwall llwytho'r gweinydd datblygwr mewnol. Gwenwch yn siŵr ei fod wedi ei becynnu a gwiriwch eich consol gwall am negeseuon.
diff --git a/l10n-cy/mail/chrome/messenger/downloadheaders.dtd b/l10n-cy/mail/chrome/messenger/downloadheaders.dtd
new file mode 100644
index 0000000000..88e3ddc178
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/downloadheaders.dtd
@@ -0,0 +1,27 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY all.label          "Llwytho pob pennyn i lawr">
+<!ENTITY all.accesskey      "p">
+<!--LOCALIZATION NOTE (download.label):
+    consider the download.label and headers.label as a single sentence
+   with the number of headers to be downloaded inserted between them:
+   EXAMPLE: "Download" <some number> "headers"
+   Either label could be set to null ("") if required grammatically.
+-->
+
+<!--LOCALIZATION NOTE (download.label):
+    consider the download.label and headers.label as a single sentence
+    with the number of headers to be downloaded inserted between them:
+    EXAMPLE: "Download" <some number> "headers"
+    Either label could be set to null ("") if required grammatically.
+-->
+
+<!ENTITY download.label     "Llwytho i Lawr">
+<!ENTITY download.accesskey "L">
+<!--LOCALIZATION NOTE (headers.label): see note for download.label -->
+<!ENTITY headers.label      "penynnau">
+<!ENTITY headers.accesskey  "p">
+<!ENTITY mark.label         "Marcio gweddill y penynnau fel wedi darllen">
+<!ENTITY mark.accesskey     "M">
diff --git a/l10n-cy/mail/chrome/messenger/editContactOverlay.dtd b/l10n-cy/mail/chrome/messenger/editContactOverlay.dtd
new file mode 100644
index 0000000000..d8dff07314
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/editContactOverlay.dtd
@@ -0,0 +1,20 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY editContactPanelDeleteContact.label "Dileu">
+<!ENTITY editContactPanelDeleteContact.accesskey "D">
+
+<!ENTITY editContactName.label "Enw:">
+<!ENTITY editContactName.accesskey "E">
+
+<!ENTITY editContactEmail.label "E-bost:">
+<!ENTITY editContactEmail.accesskey "b">
+
+<!ENTITY editContactAddressBook.label "Llyfr Cyfeiriadau:">
+<!ENTITY editContactAddressBook.accesskey "L">
+
+<!ENTITY editContactPanelDone.label "Gorffen">
+<!ENTITY editContactPanelDone.accesskey "G">
+
+<!ENTITY contactMoveDisabledWarning.description "Nid oes modd newid y llyfr cyfeiriadau gan fod y cysylltiad mewn rhestr e-bostio.">
diff --git a/l10n-cy/mail/chrome/messenger/editContactOverlay.properties b/l10n-cy/mail/chrome/messenger/editContactOverlay.properties
new file mode 100644
index 0000000000..f2a19d2916
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/editContactOverlay.properties
@@ -0,0 +1,14 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+editTitle=Golygu Cysylltiad
+viewTitle=Gweld Cysylltiad
+
+editDetailsLabel=Golygu Manylion
+editDetailsAccessKey=M
+viewDetailsLabel=Gweld Manylion
+viewDetailsAccessKey=G
+
+deleteContactTitle=Dileu Cysylltiad
+deleteContactMessage=Ydych chi'n siŵr eich bod eisiau dileu'r Cysylltiad?
diff --git a/l10n-cy/mail/chrome/messenger/fieldMapImport.dtd b/l10n-cy/mail/chrome/messenger/fieldMapImport.dtd
new file mode 100644
index 0000000000..1212ff9141
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/fieldMapImport.dtd
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY fieldMapImport.next.label "Nesaf">
+<!ENTITY fieldMapImport.next.accesskey "N">
+<!ENTITY fieldMapImport.previous.label "Blaenorol">
+<!ENTITY fieldMapImport.previous.accesskey "B">
+<!ENTITY fieldMapImport.text "Defnyddiwch Symud i Fyny a Symud i Lawr i gydweddu meysydd y llyfr cyfeiriadau ar y chwith gyda'r data cywir i'w fewnforio ar y dde. Dad-diciwch eitemau nad ydych am eu mewnforio.">
+<!ENTITY fieldMapImport.up.label "Symud i Fyny">
+<!ENTITY fieldMapImport.up.accesskey "F">
+<!ENTITY fieldMapImport.down.label "Symud i Lawr">
+<!ENTITY fieldMapImport.down.accesskey "L">
+<!ENTITY fieldMapImport.fieldListTitle "Meysydd Llyfr Cyfeiriadau">
+<!ENTITY fieldMapImport.dataTitle "Cofnodi data i'w fewnforio">
+<!ENTITY fieldMapImport.skipFirstRecord.label "Mae'r cofnod cyntaf yn cynnwys enwau meysydd">
+<!ENTITY fieldMapImport.skipFirstRecord.accessKey "c">
diff --git a/l10n-cy/mail/chrome/messenger/filter.properties b/l10n-cy/mail/chrome/messenger/filter.properties
new file mode 100644
index 0000000000..7bf4088cf4
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/filter.properties
@@ -0,0 +1,108 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+mustSelectFolder=Rhaid dewis ffolder targed.
+enterValidEmailAddress=Rhowch gyfeiriad e-bost dilys i'w anfon ymlaen.
+pickTemplateToReplyWith=Dewiswch dempled i ymateb.
+mustEnterName=Rhaid rhoi enw i'r hidl.
+cannotHaveDuplicateFilterTitle=Dyblygu Enw'r Hidl
+cannotHaveDuplicateFilterMessage=Mae'r enw hidl rydych wedi'i roi yn bodoli eisoes. Rhowch enw hidl gwahanol.
+mustHaveFilterTypeTitle=Heb ddewis hidl digwyddiad
+mustHaveFilterTypeMessage=Rhaid dewis o leiaf un digwyddiad pan mae'r hidl yn cael ei osod. Os nad ydych am i'r hidl redeg dros dro ar gyfer unrhyw ddigwyddiad, dad-diciwch ei gyflwr gweithredol yn y deialog Hidlau Negeseuon.
+deleteFilterConfirmation=Ydych chi'n siŵr eich bod eisiau dileu'r hidl(au)?
+matchAllFilterName=Cydweddu Pob Neges
+filterListBackUpMsg=Nid yw eich hidlau'n gweithio oherwydd nad oes modd darllen ffeil msg.FilterRules.dat sy'n cynnwys eich hidlau. Bydd ffeil msg.FilterRules.dat newydd yn cael ei greu a bydd yr hen ffeil yn cael ei gadw ar ffurf rulesbackup.dat yn yr un cyfeiriadur.
+customHeaderOverflow=Rydych wedi mynd dros yr uchafswm o 50 penynnau cyfaddasu. Tynnwch un neu ragor o'r penynnau cyfaddasu a cheisiwch eto.
+filterCustomHeaderOverflow=Mae eich hidlau wedi mynd dros y terfyn o 50 pennyn cyfaddasu. Golygwch y ffeil msgFilterRules.dat, sy'n cynnwys eich hidlau, i ddefnyddio llai o benynnau hidlo.
+invalidCustomHeader=Mae un o'ch hidlau'n cynnwys pennyn cyfaddasu sy'n cynnwys nod annilys, fel ':', nod anargraffadwy, nod nad yw'n ascii neu nod ascii wyth did. Golygwch y ffeil msgFilterRulesrules.dat, sy'n cynnwys eich hidlau, i dynnu'r nodau annilys o'ch pennyn cyfaddasu.
+continueFilterExecution=Methodd gosod yr hidl %S. Hoffech chi barhau i osod yr hidlau?
+promptTitle=Rhedeg Hidlau
+promptMsg=Rydych yn y broses o hidlo negeseuon.\nHoffech chi barhau i osod yr hidlau?
+stopButtonLabel=Atal
+continueButtonLabel=Parhau
+# LOCALIZATION NOTE(cannotEnableIncompatFilter)
+# %S=the name of the application
+cannotEnableIncompatFilter=Cafodd yr hidl ei greu gan fersiwn y dyfodol neu anghymarus o %S. Nid oes modd galluogi'r hidl am nad ydym yn gwybod sut mae ei weithredu.
+dontWarnAboutDeleteCheckbox=Peidio â gofyn eto
+# LOCALIZATION NOTE(copyToNewFilterName)
+# %S=the name of the filter that is being copied
+copyToNewFilterName=Copi o %S
+# LOCALIZATION NOTE(contextPeriodic.label): Semi-colon list of plural forms.
+# #1=the number of minutes
+contextPeriodic.label=O bryd i'w gilydd, bob munud;O bryd i'w gilydd, bob #1 munud;O bryd i'w gilydd, bob #1 munud;O bryd i'w gilydd, bob #1 munud;O bryd i'w gilydd, bob #1 munud;O bryd i'w gilydd, bob #1 munud
+
+# LOCALIZATION NOTE(filterFailureWarningPrefix)
+# %1$S=filter error action
+# %2$S=error code as hexadecimal string.
+filterFailureWarningPrefix=Methodd Gweithredu'r Hidl: "%1$S" gyda error code=%2$S wrth geisio:
+filterFailureSendingReplyError=Gwall wrth anfon ateb
+filterFailureSendingReplyAborted=Ataliwyd anfon yr ateb
+filterFailureMoveFailed=Methodd y symud
+filterFailureCopyFailed=Methodd y copïo
+filterFailureAction=Methu gosod y weithred hidlo
+
+searchTermsInvalidTitle=Termau Chwilio yn Annilys
+# LOCALIZATION NOTE(searchTermsInvalidRule)
+# %1$S=search attribute name from the invalid rule
+# %2$S=search operator from the bad rule
+searchTermsInvalidRule=Nid oes modd cadw'r hidl gan fod y term chwilio "%1$S %2$S" yn annilys yn y cyd-destun cyfredol.
+# LOCALIZATION NOTE(filterActionOrderExplanation)
+# Keep the \n\n that mean 2 linebreaks.
+filterActionOrderExplanation=Pan fydd neges yn cydweddu'r hidl bydd gweithredoedd yn cael eu rhedeg yn y drefn yma:\n\n
+filterActionOrderTitle=Trefn gweithredu go iawn
+## LOCALIZATION NOTE(filterActionItem):
+# %1$S=sequence number of the action, %2$S=action text, %3$S=action argument
+filterActionItem=%1$S. %2$S %3$S\n
+
+## LOCALIZATION NOTE(filterCountVisibleOfTotal):
+# %1$S=number of matching filters, %2$S=total number of filters
+filterCountVisibleOfTotal=%1$S o %2$S
+## LOCALIZATION NOTE(filterCountItems):
+## Semicolon-separated list of singular and plural forms.
+## See: https://developer.mozilla.org/en/docs/Localization_and_Plurals
+## #1 is the count of items in the list.
+filterCountItems=0 eitemau;#1 eitem;#1 eitem;#1 eitem;#1 eitem;#1 eitem
+# for junk mail logging / mail filter logging
+# LOCALIZATION NOTE(junkLogDetectStr)
+# %1$S=author, %2$S=subject, %3$S=date
+junkLogDetectStr=Neges sbam wedi'i ganfod o %1$S - %2$S yn %3$S
+# LOCALIZATION NOTE(logMoveStr)
+# %1$S=message id, %2$S=folder URI
+logMoveStr=symud enw'r neges = %1$S i %2$S
+# LOCALIZATION NOTE(logCopyStr)
+# %1$S=message id, %2$S=folder URI
+logCopyStr=copïwyd enw neges = %1$S i %2$S
+# LOCALIZATION NOTE(filterLogLine):
+# %1$S=timestamp, %2$S=log message
+filterLogLine=[%1$S] %2$S
+# LOCALIZATION NOTE(filterMessage):
+# %1$S=filter name, %1$S=log message
+filterMessage=Neges o hidl "%1$S": %2$S
+# LOCALIZATION NOTE(filterLogDetectStr)
+# %1$S=filter name %2$S=author, %3$S=subject, %4$S=date
+filterLogDetectStr=Gosod hidl "%1$S" i neges gan %2$S - %3$S ar %4$S
+filterMissingCustomAction=Gweithred Cyfaddas Coll
+filterAction2=blaenoriaeth wedi newid
+filterAction3=dilëwyd
+filterAction4=marcio wedi darllen
+filterAction5=lladd edefyn
+filterAction6=edefyn yn cael ei wylio
+filterAction7=serenog
+filterAction8=tagiwyd
+filterAction9=atebwyd
+filterAction10=wedi'i anfon ymlaen
+filterAction11=atal gweithredu
+filterAction12=dilëwyd o'r gweinydd POP3
+filterAction13=gadawyd ar y gweinydd POP3
+filterAction14=sgôr sbam
+filterAction15=estyn y corff o weinydd POP3
+filterAction16=copïwyd i'r ffolder
+filterAction17=tagiwyd
+filterAction18=anwybyddwyd is-edefyn
+filterAction19=marcio heb ddarllen
+# LOCALIZATION NOTE(filterAutoNameStr)
+# %1$S=Header or item to match, e.g. "From", "Tag", "Age in days", etc.
+# %2$S=Operator, e.g. "Contains", "is", "is greater than", etc.
+# %3$S=Value, e.g. "Steve Jobs", "Important", "42", etc.
+filterAutoNameStr=%1$S %2$S: %3$S
diff --git a/l10n-cy/mail/chrome/messenger/folderProps.dtd b/l10n-cy/mail/chrome/messenger/folderProps.dtd
new file mode 100644
index 0000000000..388c7dcc80
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/folderProps.dtd
@@ -0,0 +1,70 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY folderProps.windowtitle.label           "Priodweddau">
+
+<!ENTITY generalInfo.label                       "Gwybodaeth Gyffredinol">
+<!ENTITY folderRebuildSummaryFileTip2.label      "Ailadeiladu'r Mynegai Ffeil Cryno">
+<!ENTITY folderRebuildSummaryFile2.label         "Trwsio'r Ffolder">
+<!ENTITY folderRebuildSummaryFile2.accesskey     "T">
+<!ENTITY folderRebuildSummaryFile.explanation    "Weithiau bydd y ffeil mynegai'r ffolder (..msf) yn cael ei difrodi ac mae modd i negeseuon sy'n ymddangos ar goll neu ffeiliau sydd wedi'u dileu parhau i gael eu dangos; gall drwsio'r ffolder ddatrys y problemau hyn.">
+<!ENTITY folderIncludeInGlobalSearch.label       "Cynnwys y negeseuon yn y ffolder yng nghanlyniadau'r Chwilio Eang">
+<!ENTITY folderIncludeInGlobalSearch.accesskey   "n">
+
+<!ENTITY retention.label "Polisi Cadw">
+<!ENTITY retentionUseAccount.label  "Defnyddio gosodiadau fy nghyfrif">
+<!ENTITY retentionUseAccount.accesskey "D">
+<!ENTITY daysOld.label "diwrnod oed">
+<!ENTITY message.label "negeseuon">
+<!ENTITY retentionCleanup.label "I adfer lle ar ddisg, mae modd dileu hen negeseuon yn barhaol.">
+<!ENTITY retentionCleanupImap.label "I adfer lle ar ddisg, mae modd dileu hen negeseuon yn barhaol yn gopïau lleol a'r gwreiddiol ar y gweinydd pell.">
+<!ENTITY retentionCleanupPop.label "I adfer lle ar ddisg, mae modd dileu hen negeseuon yn barhaol gan gynnwys y gwreiddiol ar y gweinydd pell.">
+<!ENTITY retentionDeleteMsg.label "Dileu negeseuon mwy na">
+<!ENTITY retentionDeleteMsg.accesskey "i">
+<!ENTITY retentionKeepAll.label "Peidio dileu unrhyw neges">
+<!ENTITY retentionKeepAll.accesskey "P">
+<!ENTITY retentionKeepRecent.label "Dileu pob un heblaw'r mwyaf diweddar">
+<!ENTITY retentionKeepRecent.accesskey "l">
+<!ENTITY retentionApplyToFlagged.label "Cadw negeseuon serennog pob tro">
+<!ENTITY retentionApplyToFlagged.accesskey "s">
+
+<!ENTITY folderSynchronizationTab.label          "Cydweddu">
+<!ENTITY folderCheckForNewMessages2.label         "Wrth dderbyn negeseuon newydd ar gyfer y cyfrif hwn, gwirio'r ffolder bob tro">
+<!ENTITY folderCheckForNewMessages2.accesskey     "g">
+
+<!ENTITY offlineFolder.check.label               "Dewis y ffolder ar gyfer defnydd all-lein">
+<!ENTITY offlineFolder.check.accesskey           "D">
+<!ENTITY offlineFolder.button.label              "Llwytho i Lawr Nawr">
+<!ENTITY offlineFolder.button.accesskey          "L">
+
+<!ENTITY selectofflineNewsgroup.check.label      "Dewiswch y grŵp newyddion ar gyfer defnydd all-lein">
+<!ENTITY selectofflineNewsgroup.check.accesskey  "a">
+<!ENTITY offlineNewsgroup.button.label           "Llwytho i Lawr Nawr">
+<!ENTITY offlineNewsgroup.button.accesskey       "L">
+
+<!ENTITY folderProps.name.label                  "Enw:">
+<!ENTITY folderProps.name.accesskey              "E">
+<!ENTITY folderProps.color.label                 "Lliw Eicon:">
+<!ENTITY folderProps.color.accesskey             "E">
+<!ENTITY folderProps.reset.tooltip               "Adfer lliw rhagosodedig">
+<!ENTITY folderProps.location.label              "Lleoliad:">
+<!ENTITY folderProps.location.accesskey          "L">
+
+<!ENTITY folderSharingTab.label                  "Rhannu">
+<!ENTITY privileges.button.label                 "Breintiau…">
+<!ENTITY privileges.button.accesskey             "B">
+<!ENTITY permissionsDesc.label                   "Mae gennych y caniatâd canlynol:">
+<!ENTITY folderOtherUsers.label                  "Eraill sydd â mynediad at y ffolder hon:">
+<!ENTITY folderType.label                        "Math o Ffolder:">
+
+<!ENTITY folderQuotaTab.label                    "Cwota">
+<!ENTITY folderQuotaUsage.label                  "Defnydd:">
+<!ENTITY folderQuotaStatus.label                 "Statws:">
+
+<!ENTITY numberOfMessages.label                  "Nifer o negeseuon:">
+<!-- LOCALIZATION NOTE: When the number of messages can't be determined, this string is displayed as the number -->
+<!ENTITY numberUnknown.label                     "anhysbys">
+<!ENTITY sizeOnDisk.label                        "Maint ar ddisg:">
+<!-- LOCALIZATION NOTE: When the size can't be determined, this string is displayed as the size -->
+<!ENTITY sizeUnknown.label                       "anhysbys">
diff --git a/l10n-cy/mail/chrome/messenger/folderWidgets.properties b/l10n-cy/mail/chrome/messenger/folderWidgets.properties
new file mode 100644
index 0000000000..fbf90ca56d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/folderWidgets.properties
@@ -0,0 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE(globalInbox)
+# %S=name of the Local folders account
+globalInbox=Blwch Derbyn Popeth (%S)
+# LOCALIZATION NOTE(verboseFolderFormat): %1$S is folder name, %2$S is server name
+verboseFolderFormat=%1$S ar %2$S
+chooseFolder=Dewis Ffolder…
+chooseAccount=Dewis Cyfrif…
+noFolders=Dim ffolderi ar gael
diff --git a/l10n-cy/mail/chrome/messenger/folderpane.dtd b/l10n-cy/mail/chrome/messenger/folderpane.dtd
new file mode 100644
index 0000000000..cbf9b84618
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/folderpane.dtd
@@ -0,0 +1,7 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!ENTITY nameColumn.label   "Enw"> 
+<!ENTITY unreadColumn.label "Heb ei Ddarllen"> 
+<!ENTITY totalColumn.label "Cyfanswm"> 
+<!ENTITY folderSizeColumn.label "Maint"> 
diff --git a/l10n-cy/mail/chrome/messenger/gloda.properties b/l10n-cy/mail/chrome/messenger/gloda.properties
new file mode 100644
index 0000000000..8a98fcf13a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/gloda.properties
@@ -0,0 +1,175 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (*.facetNameLabel): These are the labels used to label the facet
+#  displays in the global search facet display mechanism.  They should be
+#  compact descriptions of the facet type (e.g. "Folder", and don't need to
+#  refer to the objects being faceted (e.g. "Message" or "Mail").
+
+# LOCALIZATION NOTE (*.includeLabel): The label to use for the included group
+#  in the facet display. If not provided, we will fall back to
+#  "glodaFacetView.facets.included.fallbackLabel".
+
+# LOCALIZATION NOTE (*.excludeLabel): The label to use for the excluded group
+#  in the facet display. If not provided, we will fall back to
+#  "glodaFacetView.facets.excluded.fallbackLabel".
+
+# LOCALIZATION NOTE (*.remainderLabel): The label to use for the remaining items
+#  that are neither part of the included group or the excluded group in the
+#  facet display. If not provided, we will fall back to
+#  "glodaFacetView.facets.remainder.fallbackLabel".
+
+# LOCALIZATION NOTE (*.mustMatchLabel): The label to use for the popup menu
+#  to indicate that the results should be restricted to messages which match
+#  a particular value. If not provided, we will fall back to
+#  "glodaFacetView.facets.mustMatch.fallbackLabel".  #1, if present, is
+#  replaced by the value of the facet (name, folder, mailing list, etc.)
+
+# LOCALIZATION NOTE (*.cantMatchLabel): The label to use for the popup menu
+#  to indicate that the results should be restricted to messages which match
+#  a particular value. If not provided, we will fall back to
+#  "glodaFacetView.facets.cantMatch.fallbackLabel".  #1, if present, is
+#  replaced by the value of the facet (name, folder, mailing list, etc.)
+
+# LOCALIZATION NOTE (*.mayMatchLabel): The label to use for the popup menu
+#  to indicate that the results should no longer be restricted relative to
+#  this particular facet value. If not provided, we will fall back to
+#  "glodaFacetView.facets.mayMatch.fallbackLabel".  #1, if present, is
+#  replaced by the value of the facet (name, folder, mailing list, etc.)
+
+# LOCALIZATION NOTE (*.mustMatchSomeLabel): The label to use for the popup menu
+#  to indicate that the results should be restricted to messages which have
+#  _some_ value (e.g. at least one tag is set). If not provided, we will fall
+#  back to "glodaFacetView.facets.mustMatchSome.fallbackLabel".  #1, if present,
+#  is replaced by the value of the facet (name, folder, mailing list, etc.)
+
+# LOCALIZATION NOTE (*.mustMatchNoneLabel): The label to use for the popup menu
+#  to indicate that the results should be restricted to messages which have _no_
+#  value (e.g. no tags are set). If not provided, we will fall back to
+#  "glodaFacetView.facets.mustMatchNoneLabel.fallbackLabel".  #1, if present, is
+#  replaced by the value of the facet (name, folder, mailing list, etc.)
+
+# LOCALIZATION NOTE (*.mayMatchAnyLabel): The label to use for the popup menu
+#  to indicate that the results should not be restricted to messages which have
+#  any or no value (e.g. no requirements on any tags are set). If not provided,
+#  we will fall back to "glodaFacetView.facets.mayMatchAnyLabel.fallbackLabel".
+#  #1, if present, is replaced by the value of the facet (name, folder, mailing
+#  list, etc.)
+
+# LOCALIZATION NOTE (gloda.message.attr.account.*): Stores the account in which
+#  a message's folder is located.
+gloda.message.attr.account.facetNameLabel=Cyfrif
+gloda.message.attr.account.includeLabel=wedi'i storio yn unrhyw un o:
+gloda.message.attr.account.excludeLabel=heb ei storio yn:
+gloda.message.attr.account.remainderLabel=cyfrifon eraill:
+gloda.message.attr.account.mustMatchLabel=rhaid ei fod yn #1
+gloda.message.attr.account.cantMatchLabel=nid yw yn #1
+
+# LOCALIZATION NOTE (gloda.message.attr.folder.*): Stores the message folder in
+#  which the message is stored.
+gloda.message.attr.folder.facetNameLabel=Ffolder
+gloda.message.attr.folder.includeLabel=wedi'i storio yn unrhyw un o:
+gloda.message.attr.folder.excludeLabel=heb ei storio yn:
+gloda.message.attr.folder.remainderLabel=ffolderi eraill:
+gloda.message.attr.folder.mustMatchLabel=rhaid ei fod yn #1
+gloda.message.attr.folder.cantMatchLabel=nid yw yn #1
+
+# LOCALIZATION NOTE (gloda.message.attr.fromMe.*): Stores everyone involved
+#  with the message.  This means from/to/cc/bcc.
+gloda.message.attr.fromMe.facetNameLabel=Oddi wrthyf i
+
+# LOCALIZATION NOTE (gloda.message.attr.toMe.*): Stores everyone involved
+#  with the message.  This means from/to/cc/bcc.
+gloda.message.attr.toMe.facetNameLabel=Ataf i
+
+# LOCALIZATION NOTE (gloda.message.attr.involves.*): Stores everyone involved
+#  with the message.  This means from/to/cc/bcc.
+gloda.message.attr.involves.facetNameLabel=Pobl
+gloda.message.attr.involves.includeLabel=yn ymwneud â:
+gloda.message.attr.involves.excludeLabel=ddim yn cynnwys:
+gloda.message.attr.involves.remainderLabel=cyfrannwr eraill:
+gloda.message.attr.involves.mustMatchLabel=rhaid ymwneud â #1
+gloda.message.attr.involves.cantMatchLabel=nid yn ymwneud â #1
+
+# LOCALIZATION NOTE (gloda.message.attr.date.*): Stores the date of the message.
+#  Thunderbird normally stores the date the message claims it was composed
+#  according to the "Date" header.  This is not the same as when the message
+#  was sent or when it was eventually received by the user.  In the future we
+#  may change this to be one of the other dates, but not anytime soon.
+gloda.message.attr.date.facetNameLabel=Dyddiad
+
+# LOCALIZATION NOTE (gloda.message.attr.attachmentTypes.*): Stores the list of
+#  MIME types (ex: image/png, text/plain) of real attachments (not just part of
+#  the message content but explicitly named attachments) on the message.
+#  Although we hope to be able to provide localized human-readable explanations
+#  of the MIME type (ex: "PowerPoint document"), I don't know if that is going
+#  to happen.
+gloda.message.attr.attachmentTypes.facetNameLabel=Atodiadau
+
+# LOCALIZATION NOTE (gloda.message.attr.mailing-list.*): Stores the mailing
+#  lists detected in the message.  This will normally be the e-mail address of
+#  the mailing list and only be detected in messages received from the mailing
+#  list.  Extensions may contribute additional detected mailing-list-like
+#  things.
+gloda.message.attr.mailing-list.facetNameLabel=Rhestr E-bost
+gloda.message.attr.mailing-list.noneLabel=Dim
+gloda.message.attr.mailing-list.includeLabel=wedi derbyn o unrhyw un o:
+gloda.message.attr.mailing-list.excludeLabel=heb ei dderbyn ar unrhyw un o:
+gloda.message.attr.mailing-list.remainderLabel=rhestrau e-bostio eraill:
+gloda.message.attr.mailing-list.mustMatchLabel=rhaid ei fod yn #1
+gloda.message.attr.mailing-list.cantMatchLabel=nid yw yn #1
+gloda.message.attr.mailing-list.mustMatchSomeLabel=rhaid ei fod mewn rhestr e-bost
+gloda.message.attr.mailing-list.mustMatchNoneLabel=nid yw mewn rhestr e-bostio
+
+# LOCALIZATION NOTE (gloda.message.attr.tag.*): Stores the tags applied to the
+#  message.  Notably, gmail's labels are not currently exposed via IMAP and we
+#  do not do anything clever with gmail, so this is independent of gmail labels
+#  This may change in the future, but it's a safe bet it's not happening on
+#  Thunderbird's side prior to 3.0.
+gloda.message.attr.tag.facetNameLabel=Tagiau
+gloda.message.attr.tag.noneLabel=Dim
+gloda.message.attr.tag.includeLabel=tagio o unrhyw un o:
+gloda.message.attr.tag.excludeLabel=heb ei dagio:
+gloda.message.attr.tag.remainderLabel=tagiau eraill:
+gloda.message.attr.tag.mustMatchLabel=rhaid fod wedi tagio #1
+gloda.message.attr.tag.cantMatchLabel=nid yw wedi'i dagio #1
+gloda.message.attr.tag.mustMatchSomeLabel=rhaid fod wedi tagio
+gloda.message.attr.tag.mustMatchNoneLabel=nid yw wedi'i dagio
+
+# LOCALIZATION NOTE (gloda.message.attr.star.*): Stores whether the message is
+#  starred or not, as indicated by a pretty star icon.  In the past, the icon
+#  used to be a flag.  The IMAP terminology continues to be "flagged".
+gloda.message.attr.star.facetNameLabel=Serennog
+
+# LOCALIZATION NOTE (gloda.message.attr.read.*): Stores whether the user has
+#  read the message or not.
+gloda.message.attr.read.facetNameLabel=Darllenwyd
+
+# LOCALIZATION NOTE (gloda.message.attr.repliedTo.*): Stores whether we believe
+#  the user has ever replied to the message.  We normally show a little icon in
+#  the thread pane when this is the case.
+gloda.message.attr.repliedTo.facetNameLabel=Atebwyd i
+
+# LOCALIZATION NOTE (gloda.message.attr.forwarded.*): Stores whether we believe
+#  the user has ever forwarded the message.  We normally show a little icon in
+#  the thread pane when this is the case.
+gloda.message.attr.forwarded.facetNameLabel=Ymlaen
+
+# LOCALIZATION NOTE (gloda.mimetype.category.*.label): Map categories of MIME
+#  types defined in MimeTypeCategories.jsm to labels.
+# LOCALIZATION NOTE (gloda.mimetype.category.archives.label): Archive is
+#  referring to things like zip files, tar files, tar.gz files, etc.
+gloda.mimetype.category.archives.label=Archifau
+gloda.mimetype.category.documents.label=Dogfennau
+gloda.mimetype.category.images.label=Delweddau
+# LOCALIZATION NOTE (gloda.mimetype.category.media.label): Media is meant to
+#  encompass both audio and video.  This is because video and audio streams are
+#  frequently stored in the same type of container and we cannot rely on the
+#  sending e-mail client to have been clever enough to figure out what was
+#  really in the file.  So we group them together.
+gloda.mimetype.category.media.label=Cyfrwng (Sain, Fideo)
+gloda.mimetype.category.pdf.label=Ffeiliau PDF
+# LOCALIZATION NOTE (gloda.mimetype.category.other.label): Other is the category
+#  for MIME types that we don't really know what it is.
+gloda.mimetype.category.other.label=Arall
diff --git a/l10n-cy/mail/chrome/messenger/glodaComplete.properties b/l10n-cy/mail/chrome/messenger/glodaComplete.properties
new file mode 100644
index 0000000000..e407e1a7f1
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/glodaComplete.properties
@@ -0,0 +1,19 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (glodaComplete.messagesTagged.label): The label used
+#  in the autocomplete widget to refer to a query for all messages tagged
+#  by a particular tag (replacing #1).
+glodaComplete.messagesTagged.label=Negeseuon wedi'u tagio: #1
+
+# LOCALIZATION NOTE (glodaComplete.messagesMentioning.label): The label used
+#  in the autocomplete widget to refer to a search for all messages mentioning
+#  a particular word (replacing #1).
+glodaComplete.messagesMentioning.label=Negeseuon yn sôn am: #1
+
+# LOCALIZATION NOTE (glodaComplete.messagesWithMany.label): The label used
+#  in the autocomplete widget to refer to a search for all messages mentioning
+#  a set of words, or a phrase containing multiple words (e.g. "red pepper")
+#  We use the same words in en-US, but maybe that's not always true.
+glodaComplete.messagesMentioningMany.label=Negeseuon yn sôn am: #1
diff --git a/l10n-cy/mail/chrome/messenger/glodaFacetView.dtd b/l10n-cy/mail/chrome/messenger/glodaFacetView.dtd
new file mode 100644
index 0000000000..5bf0e3c049
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/glodaFacetView.dtd
@@ -0,0 +1,29 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- LOCALIZATION NOTE (glodaFacetView.filters.label): Label at the top of the
+     faceting sidebar.  Serves as a header both for the checkboxes under it as
+     well for labeled facets with multiple options. -->
+<!ENTITY glodaFacetView.filters.label "Hidlau">
+
+<!-- LOCALIZATION NOTE (glodaFacetView.loading.label): Label that appears when
+     the search results take a long time to appear. -->
+<!ENTITY glodaFacetView.loading.label "Chwilio&#8230;">
+
+<!-- LOCALIZATION NOTE (glodaFacetView.empty.label): Label that appears when
+     there are no results that match the search query. -->
+<!ENTITY glodaFacetView.empty.label "Dim negeseuon yn cyd-fynd â'ch chwilio">
+
+<!-- LOCALIZATION NOTE (glodaFacetView.pageMore.label): Label at the bottom
+     of the results list to show more hits. -->
+<!ENTITY glodaFacetView.pageMore.label "Rhagor »">
+
+<!-- LOCALIZATION NOTE(glodaFacetView.results.message.openEmailAsList.label2): The
+     label for the button/link that causes us to display all of the emails in
+     the active set in a new thread pane display tab. -->
+<!ENTITY glodaFacetView.openEmailAsList.label "Dangos y canlyniadau fel rhestr">
+
+<!-- LOCALIZATION NOTE(glodaFacetView.results.message.openEmailAsList.tooltip):
+     The tooltip to display when hovering over the openEmailAsList label. -->
+<!ENTITY glodaFacetView.openEmailAsList.tooltip "Dangos yr holl negeseuon e-bost yn y set weithredol mewn tab newydd">
diff --git a/l10n-cy/mail/chrome/messenger/glodaFacetView.properties b/l10n-cy/mail/chrome/messenger/glodaFacetView.properties
new file mode 100644
index 0000000000..eaffc78d45
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/glodaFacetView.properties
@@ -0,0 +1,171 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (glodaFacetView.tab.query.label):
+#  The tab title to display for tabs that are based on a gloda (global database)
+#  query or collection rather than a user search.  At some point we might try
+#  and explain what the query/collection is in automatic fashion, but not today.
+glodaFacetView.tab.query.label=Chwilio
+
+# LOCALIZATION NOTE (glodaFacetView.tab.search.label):
+#  The tab title to display for tabs with a new gloda (global database)
+#  user search (rather than a query or collection) without a search string.
+#  After the search has been started, we just display the search string entered
+#  by the user.
+glodaFacetView.tab.search.label=Chwilio
+
+# LOCALIZATION NOTE(glodaFacetView.search.label2):
+#  The heading for the search page.
+#  A short description of user's search query will be appended.
+glodaFacetView.search.label2=Canlyniadau:
+
+# LOCALIZATION NOTE(glodaFacetView.constraints.query.fulltext.label):
+#  The label to display to describe when our base query was a fulltext search
+#  across messages.  The value is displayed following the label.
+glodaFacetView.constraints.query.fulltext.label=Chwilio am #1
+glodaFacetView.constraints.query.fulltext.andJoinWord=a
+glodaFacetView.constraints.query.fulltext.orJoinWord=neu
+
+# LOCALIZATION NOTE(glodaFacetView.constraints.query.initial):
+#  The label to display to describe when our base query is not a full-text
+#  search.  Additional labels are appended describing each constraint.
+glodaFacetView.constraints.query.initial=Chwilio am negeseuon
+
+# LOCALIZATION NOTE(glodaFacetView.constraints.query.involves.label):
+#  The label to display to describe when our base query was on messages
+#  involving a given contact from the address book.  The value is displayed
+#  where the #1 is.
+glodaFacetView.constraints.query.involves.label=ymwneud â #1
+
+# LOCALIZATION NOTE(glodaFacetView.constraints.query.contact.label):
+#  The label to display to describe when our base query was on messages
+#  tagged with a specific tag.  The tag is displayed following the label.
+glodaFacetView.constraints.query.tagged.label=tagiwyd:
+
+
+# LOCALIZATION NOTE (glodaFacetView.facets.mode.top.listAllLabel): The label to
+#  use when we are only displaying the top entries for a facet.  When the
+#  label is clicked on, it results in us displaying all of the values for that
+#  facet.  The value "#1" (if present) is replaced with the total number of
+#  values that will be displayed (rather than the number currently hidden).
+# This string supports pluralization.  See
+#  https://developer.mozilla.org/en/Localization_and_Plurals for details on
+#  how this stuff works.
+glodaFacetView.facets.mode.top.listAllLabel=Rhestru dim;Rhestru'r #1 i gyd;Rhestru'r #1 i gyd;Rhestru'r #1 i gyd;Rhestru'r #1 i gyd;Rhestru'r #1 i gyd
+
+# LOCALIZATION NOTE (glodaFacetView.facets.included.fallbackLabel): The label to
+#  use for groups in a facet that have been explicitly included by the user if
+#  there is no explicit attribute "includeLabel" defined.  (The explicit label
+#  would be named "gloda.message.attr.ATTRIBUTE.includeLabel".)
+glodaFacetView.facets.included.fallbackLabel=cynnwys unrhyw un o:
+# LOCALIZATION NOTE (glodaFacetView.facets.excluded.fallbackLabel): The label to
+#  use for groups in a facet that have been explicitly excluded by the user if
+#  there is no explicit attribute "excludeLabel" defined.  (The explicit label
+#  would be named "gloda.message.attr.ATTRIBUTE.excludeLabel".)
+glodaFacetView.facets.excluded.fallbackLabel=peidio cynnwys:
+# LOCALIZATION NOTE (glodaFacetView.facets.remainder.fallbackLabel): The label
+#  to use for groups in a facet that are neither part of the included group or
+#  the excluded group if there is no explicit attribute "remainderLabel"
+#  defined.  (The explicit label would be named
+#  "gloda.message.attr.ATTRIBUTE.remainderLabel".)
+glodaFacetView.facets.remainder.fallbackLabel=eraill:
+
+# LOCALIZATION NOTE (glodaFacetView.facets.mustMatchLabel.fallbackLabel): The label
+#  to use to restrict a facet by a particular value if there is no explicit
+#  attribute "mustMatchLabel" defined.  (The explicit label would be named
+#  "gloda.message.attr.ATTRIBUTE.mustMatchLabel".)
+glodaFacetView.facets.mustMatchLabel.fallbackLabel=rhaid cydweddu â #1
+glodaFacetView.facets.mustMatchNoneLabel.fallbackLabel=methu cael gwerth
+
+# LOCALIZATION NOTE (glodaFacetView.facets.cantMatchLabel.fallbackLabel): The label
+#  to use to restrict a facet by the absence of a particular value if there is
+#  no explicit attribute "cantMatchLabel" defined.  (The explicit label would be
+#  named "gloda.message.attr.ATTRIBUTE.cantMatchLabel".)
+glodaFacetView.facets.cantMatchLabel.fallbackLabel=methu cydweddu â #1
+glodaFacetView.facets.mustMatchSomeLabel.fallbackLabel=rhaid cael gwerth
+
+# LOCALIZATION NOTE (glodaFacetView.facets.mayMatchLabel.fallbackLabel): The label
+#  to use to undo the restriction of a facet by a particular value if there is
+#  no explicit attribute "mayMatchLabel" defined.  (The explicit label would be
+#  named "gloda.message.attr.ATTRIBUTE.mayMatchLabel".)
+glodaFacetView.facets.mayMatchLabel.fallbackLabel=tynnu'r cyfyngiad
+glodaFacetView.facets.mayMatchAnyLabel.fallbackLabel=tynnu'r cyfyngiad
+
+# LOCALIZATION NOTE (glodaFacetView.facets.noneLabel): The text to display when
+#  a facet needs to indicate that an attribute omitted a value or was otherwise
+#  empty.
+glodaFacetView.facets.noneLabel=Dim
+
+# LOCALIZATION NOTE (glodaFacetView.facets.filter.attachmentTypes.allLabel):
+#  The label to use when all types of attachments are being displayed.
+glodaFacetView.facets.filter.attachmentTypes.allLabel=Unrhyw Fath
+
+# LOCALIZATION NOTE (glodaFacetView.result.message.fromLabel): Used in the
+#  faceted search message display to indicate the author of a message.
+# An example usage is  "from: Bob".
+glodaFacetView.result.message.fromLabel=oddi wrth:
+
+# LOCALIZATION NOTE (glodaFacetView.result.message.toLabel): Used in the
+#  faceted search message display to indicate the recipients of a message.
+# An example usage is  "to: Bob, Chuck, Don".
+glodaFacetView.result.message.toLabel=at: 
+
+# LOCALIZATION NOTE (glodaFacetView.result.message.noSubject): Used in the
+#  faceted search message display to act as a click target for messages with
+#  no subject.
+glodaFacetView.result.message.noSubject=(dim pwnc)
+
+# LOCALIZATION NOTE(glodaFacetView.results.header.countLabel):
+# This label is displayed above the list of result messages; it tells the user
+#  how many messages we are displaying in the list out of the total number of
+#  messages in the active set (the set of messages remaining after the
+#  application of the facet constraints.)
+# The goal of the various sub-parts here is to make a label along the lines of
+#  "M of N".  Because there are two numbers, this is split into two parts,
+#  'NMessages' for what in English is just the first number and 'ofN' for the
+#  "of N" part.  We then use 'grouping' to decide how to combine the two. This
+#  was suggested by Rimas Kudelis.
+# LOCALIZATION NOTE(glodaFacetView.results.header.countLabel.NMessages):
+#  The first part of the countLabel string (although you can change the order
+#  in 'grouping').  This is pluralized using the mechanism described at
+#  https://developer.mozilla.org/en/Localization_and_Plurals.  We replace
+#  "#1" with the number of messages being shown in the result list.
+glodaFacetView.results.header.countLabel.NMessages=#1;#1;#1;#1;#1;#1
+# LOCALIZATION NOTE(glodaFacetView.results.header.countLabel.ofN):
+#  The second part of the countLabel string (although you can change the order
+#  in 'grouping').  This is pluralized using the mechanism described at
+#  https://developer.mozilla.org/en/Localization_and_Plurals.  We replace
+#  "#1" with the total number of messagse in the active set.
+glodaFacetView.results.header.countLabel.ofN=o #1;o #1;o #1;o #1;o #1;o #1
+# LOCALIZATION NOTE(glodaFacetView.results.header.countLabel.grouping):
+#  Combines the pluralized
+#  "glodaFacetView.results.header.countLabel.NMessages" string (as #1) with
+#  the pluralized "glodaFacetView.results.header.countLabel.ofN" (as #2)
+#  to make a single label.
+glodaFacetView.results.header.countLabel.grouping=#1 #2
+
+glodaFacetView.results.message.timeline.label=Toglo'r llinell amser
+# LOCALIZATION NOTE(glodaFacetView.results.message.sort.relevance2):
+# a clickable label causing the sort to be done by most relevant messages first.
+glodaFacetView.results.message.sort.relevance2=Trefnu yn ôl Perthnasedd
+# LOCALIZATION NOTE(glodaFacetView.results.message.sort.date2):
+# a clickable label causing the sort to be done by most recent messages first.
+glodaFacetView.results.message.sort.date2=Trefnu yn ôl Dyddiad
+
+# LOCALIZATION NOTE(glodaFacetView.results.message.recipientSeparator): This is
+# the string in between the names of recipients (see
+# glodaFacetView.results.message.andOthers for more information).  The \u0020
+# character is a Unicode space character, which is needed as otherwise the
+# trailing whitespace is trimmed before it gets to the code.
+glodaFacetView.results.message.recipientSeparator=,\u0020
+
+# LOCALIZATION NOTE(glodaFacetView.results.message.andOthers):
+# When a message has too many recipients, we only show the first few and then
+# display this label to express how many are not displayed.  So if a message
+# has 5 recipients, we might only show the first 3, and then use this label
+# to indicate that there are 2 that are not displayed.  This string can be
+# pluralized; see https://developer.mozilla.org/en/Localization_and_Plurals
+# for details on how to do that. Note that in English, we use the "serial
+# comma", but other languages may not need a leading separator there.
+glodaFacetView.results.message.andOthers=, a #1 arall;, ac #1 arall;, a #1 arall;, a #1 arall;, a #1 arall;, a #1 arall
diff --git a/l10n-cy/mail/chrome/messenger/imAccountWizard.dtd b/l10n-cy/mail/chrome/messenger/imAccountWizard.dtd
new file mode 100644
index 0000000000..52606e366c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/imAccountWizard.dtd
@@ -0,0 +1,32 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY windowTitle.label            "Dewin Cyfrif Sgwrsio">
+
+<!ENTITY accountProtocolTitle.label   "Rhwydwaith sgwrsio">
+<!ENTITY accountProtocolInfo.label    "Dewiswch rwydwaith eich cyfrif sgwrsio.">
+<!ENTITY accountProtocolField.label   "Rhwydwaith:">
+<!ENTITY accountProtocolGetMore.label "Estyn rhagor…">
+
+<!ENTITY accountUsernameTitle.label   "Enw Defnyddiwr">
+<!ENTITY accountUsernameDuplicate.label "Mae'r cyfrif yma wedi'i ffurfweddu yn barod!">
+
+<!ENTITY accountPasswordTitle.label   "Cyfrinair">
+<!ENTITY accountPasswordInfo.label    "Rhowch eich cyfrinair yn y blwch isod.">
+<!ENTITY accountPasswordField.label   "Cyfrinair:">
+<!ENTITY accountPasswordManager.label "Bydd y cyfrinair rhoddwyd yma yn cael ei gadw o fewn y Rheolwr Cyfrineiriau. Gadewch y blwch yn wag os ydych eisiau cael eich annog am eich cyfrinair bob tro mae'r cyfrif yn cael ei gysylltu.">
+
+<!ENTITY accountAdvancedTitle.label   "Dewisiadau Uwch">
+<!ENTITY accountAdvancedInfo.label    "Teimlwch yn rhydd i hepgor y cam yma.">
+<!ENTITY accountAdvanced.newMailNotification.label   "Hysbysu am E-bost newydd">
+<!ENTITY accountAliasGroupbox.caption "Ffugenw Lleol">
+<!ENTITY accountAliasField.label      "Ffugenw:">
+<!ENTITY accountAliasInfo.label       "Dim ond pan fyddwch yn siarad yn ystod eich trafodaethau fydd hwn yn cael ei ddangos, ni fydd y cysylltiadau pell yn ei weld.">
+<!ENTITY accountProxySettings.caption "Gosodiadau'r Dirprwy">
+<!ENTITY accountProxySettings.change.label     "Newid…">
+<!ENTITY accountProxySettings.change.accessKey "N">
+
+<!ENTITY accountSummaryTitle.label   "Crynodeb">
+<!ENTITY accountSummaryInfo.label    "Mae crynodeb o'r wybodaeth rydych wedi'i gyflwyno'n cael ei ddangos isod. Gwiriwch y cynnwys cyn i'r cyfrif gael ei greu.">
+<!ENTITY accountSummary.connectNow.label "Cysylltu â'r cyfrif nawr.">
diff --git a/l10n-cy/mail/chrome/messenger/imAccounts.properties b/l10n-cy/mail/chrome/messenger/imAccounts.properties
new file mode 100644
index 0000000000..7a14e00c56
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/imAccounts.properties
@@ -0,0 +1,63 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (protoOptions):
+# %S is replaced by the name of a protocol
+protoOptions=Dewisiadau %S
+accountUsername=Enw Defnyddiwr:
+# LOCALIZATION NOTE (accountColon):
+# This string is used to append a colon after the label of each
+# option. It's localizable so that the typography can be adapted.
+accountColon=%S:
+# LOCALIZATION NOTE (accountUsernameInfo):
+# %S is replaced by the name of a protocol
+accountUsernameInfo=Rhowch enw defnyddiwr eich cyfrif %S.
+# LOCALIZATION NOTE (accountUsernameInfoWithDescription):
+# %1$S is a hint for the expected format of the username
+# %2$S is the name of a protocol
+accountUsernameInfoWithDescription=Rhowch enw defnyddiwr (%1$S) eich cyfrif %2$S.
+
+# LOCALIZATION NOTE (account.connection.error):
+# %S is the error message.
+account.connection.error=Gwall: %S
+# LOCALIZATION NOTE (account.connection.errorUnknownPrpl)
+# %S is the id (not very user friendly; hence the quotes) of the missing plugin.
+account.connection.errorUnknownPrpl=Dim protocol ategyn '%S'.
+account.connection.errorEnteringPasswordRequired=Mae angen cyfrinair i gysylltu â'r cyfrif.
+account.connection.errorCrashedAccount=Digwyddodd chwalfa wrth gysylltu â'r cyfrif.
+# LOCALIZATION NOTE (account.connection.progress):
+# %S is a message indicating progress of the connection process
+account.connection.progress=Cysylltu: %S…
+account.connecting=Cysylltu…
+account.connectedForSeconds=Wedi cysylltu am ychydig eiliadau.
+# LOCALIZATION NOTE (account.connectedFor{Double,Single},
+#                    account.reconnectIn{Double,Single}):
+# Each pair of %S is a number followed by a unit. The units are
+# already localized in a downloads.properties file of the toolkit.
+account.connectedForDouble=Wedi cysylltu ers %1$S %2$S a %3$S %4$S.
+account.connectedForSingle=Wedi cysylltu ers tua %1$S %2$S.
+account.reconnectInDouble=Ailgysylltu ymhen %1$S %2$S a %3$S %4$S.
+account.reconnectInSingle=Ailgysylltu ymhen %1$S %2$S.
+
+requestAuthorizeTitle=Cais dilysu
+# LOCALIZATION NOTE (requestAuthorizeAllow, requestAuthorizeDeny):
+# the & symbol indicates the position of the character that should be
+# used as the accesskey for this button.
+requestAuthorizeAllow=&Caniatáu
+requestAuthorizeDeny=&Gwrthod
+# LOCALIZATION NOTE (requestAuthorizeText):
+# %S is a contact username.
+requestAuthorizeText=Mae %S wedi eich ychwanegu at ei rhestr ffrindiau, hoffech chi ganiatáu iddo/iddi eich gweld chi?
+
+accountsManager.notification.button.accessKey=C
+accountsManager.notification.button.label=Cysylltu Nawr
+accountsManager.notification.userDisabled.label=Rydych wedi anablu cysylltu awtomatig.
+accountsManager.notification.safeMode.label=Mae Gosodiadau Cysylltu Awtomatig wedi'u hanwybyddu gan fod y rhaglen yn rhedeg yn y Modd Diogel.
+accountsManager.notification.startOffline.label=Mae Gosodiadau Cysylltu Awtomatig wedi'u hanwybyddu gan fod y rhaglen wedi ei chychwyn yn y Modd Diogel.
+accountsManager.notification.crash.label=Daeth y rhediad diwethaf i ben yn annisgwyl wrth geisio cysylltu. Mae Cysylltu Awtomatig wedi'i anablu er mwyn rhoi cyfle i chi Olygu eich Gosodiadau.
+# LOCALIZATION NOTE (accountsManager.notification.singleCrash.label): Semi-colon list of plural forms.
+#  See: http://developer.mozilla.org/en/docs/Localization_and_Plurals
+#  #1 is the number of accounts that are suspected to have caused a crash.
+accountsManager.notification.singleCrash.label=Daeth rhediad blaenorol i ben yn annisgwyl wrth geisio cysylltu cyfrifon newydd neu rhai wedi eu golygu. Nid yw wedi'i gysylltu er mwyn rhoi cyfle i chi Olygu eich Gosodiadau.;Daeth rhediad blaenorol  i ben yn annisgwyl wrth geisio cysylltu #1 cyfrif newydd neu wedi'u golygu. Nid ydynt wedi eu cysylltu er mwyn rhoi cyfle i chi Olygu eu Gosodiadau.;Daeth rhediad blaenorol  i ben yn annisgwyl wrth geisio cysylltu #1 gyfrif newydd neu wedi'u golygu. Nid ydynt wedi eu cysylltu er mwyn rhoi cyfle i chi Olygu eu Gosodiadau.;Daeth rhediad blaenorol  i ben yn annisgwyl wrth geisio cysylltu #1 cyfrif newydd neu wedi'u golygu. Nid ydynt wedi eu cysylltu er mwyn rhoi cyfle i chi Olygu eu Gosodiadau.;Daeth rhediad blaenorol  i ben yn annisgwyl wrth geisio cysylltu #1 cyfrif newydd neu wedi'u golygu. Nid ydynt wedi eu cysylltu er mwyn rhoi cyfle i chi Olygu eu Gosodiadau.;Daeth rhediad blaenorol  i ben yn annisgwyl wrth geisio cysylltu #1 cyfrif newydd neu wedi'u golygu. Nid ydynt wedi eu cysylltu er mwyn rhoi cyfle i chi Olygu eu Gosodiadau.
+accountsManager.notification.other.label=Mae cysylltu awtomatig wedi'i analluogi.
diff --git a/l10n-cy/mail/chrome/messenger/imapMsgs.properties b/l10n-cy/mail/chrome/messenger/imapMsgs.properties
new file mode 100644
index 0000000000..27b7874ef7
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/imapMsgs.properties
@@ -0,0 +1,266 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the imap code to display progress/status/error messages
+#
+
+#LOCALIZATION NOTE(imapAlertDialogTile): Do not translate the word "%S"
+# below. Place the word %S where the account name should appear.
+imapAlertDialogTitle=Rhybudd cyfrif %S
+
+# Status - opening folder
+imapStatusSelectingMailbox=Agor ffolder %S…
+
+# Status - create folder
+imapStatusCreatingMailbox=Creu ffolder…
+
+# Status - deleting a folder
+# LOCALIZATION NOTE (imapStatusDeletingMailbox): The "%S" below should not be translated.
+# Instead, insert "%S" in your translation where you wish to display the name
+# of the folder being deleted.
+imapStatusDeletingMailbox=Dileu ffolder %S…
+
+# Status - renaming mailbox
+# LOCALIZATION NOTE (imapStatusRenamingMailbox): The "%S" below should not be translated.
+# Instead, insert "%S" in your translation where you wish to display the name
+# of the folder being renamed.
+imapStatusRenamingMailbox=Ailenwi ffolder %S…
+
+# Status - looking for mailboxes
+imapStatusLookingForMailbox=Chwilio am ffolderi…
+
+# Status - subscribing to mailbox
+# LOCALIZATION NOTE (imapStatusSubscribeToMailbox): The "%S" below should not be translated.
+# Instead, insert "%S" in your translation where you wish to display the name
+# of the folder being subscribed to.
+imapStatusSubscribeToMailbox=Tanysgrifio i ffolder %S…
+
+# Status - unsubscribing from mailbox
+# LOCALIZATION NOTE (imapStatusUnsubscribeMailbox): The "%S" below should not be translated.
+# Instead, insert "%S" in your translation where you wish to display the name
+# of the folder being unsubscribed from.
+imapStatusUnsubscribeMailbox=Dad-danysgrifio o ffolder %S…
+
+# Status - searching imap folder
+imapStatusSearchMailbox=Chwilio'r ffolder…
+
+# Status - closing a folder
+imapStatusCloseMailbox=Cau ffolder…
+
+# Status - compacting a folder
+imapStatusExpungingMailbox=Cywasgu ffolder…
+
+# Status - logging out
+imapStatusLoggingOut=Allgofnodi…
+
+# Status - checking server capabilities
+imapStatusCheckCompat=Gwirio galluoedd gweinydd e-bost…
+
+# Status - logging on
+imapStatusSendingLogin=Anfon gwybodaeth dilysu mewngofnodi…
+
+# Status - auth logon
+imapStatusSendingAuthLogin=Anfon gwybodaeth mewngofnodi…
+
+imapDownloadingMessage=Llwytho neges i lawr…
+
+# LOCALIZATION NOTE (imapGettingACLForFolder): Do not translate the word "ACL" below.
+imapGettingACLForFolder=Estyn ffolder ACL…
+
+imapGettingServerInfo=Estyn Gwybodaeth Ffurfweddu Gweinydd…
+
+imapGettingMailboxInfo=Estyn Gwybodaeth Ffurfweddu Blwch E-bost…
+
+imapEmptyMimePart=Bydd corff yr e-bost yn cael ei lwytho i lawr yn ôl y gofyn.
+
+# LOCALIZATION NOTE (imapReceivingMessageHeaders3): Do not translate the words "%1$S", "%2$S", and "%3$S" below.
+# Place the word %1$S in your translation where the number of the header being downloaded should appear.
+# Place the word %2$S in your translation where the total number of headers to be downloaded should appear.
+# Place the word %3$S in your translation where the name of the folder being processed should appear.
+# Note: The account name and separators (e.g. colon, space) are automatically added to the status message.
+# Example: "Joe's Account: Downloading message header 100 of 1000 in Drafts…"
+imapReceivingMessageHeaders3=Llwytho %1$S pennyn neges i lawr o %2$S yn %3$S…
+
+# LOCALIZATION NOTE (imapReceivingMessageFlags3): Do not translate the words "%1$S", "%2$S", and "%3$S" below.
+# Place the word %1$S in your translation where the number of the flag being downloaded should appear.
+# Place the word %2$S in your translation where the total number of flags to be downloaded should appear.
+# Place the word %3$S in your translation where the name of the folder being processed should appear.
+# Note: The account name and separators (e.g. colon, space) are automatically added to the status message.
+# Example: "Jim's Account: Downloading message flag 100 of 1000 in INBOX…"
+imapReceivingMessageFlags3=Llwytho %1$S baner neges i lawr o %2$S yn %3$S…
+
+imapDeletingMessages=Dileu negeseuon…
+
+imapDeletingMessage=Dileu neges…
+
+# LOCALIZATION NOTE (imapMovingMessages): Do not translate the word "%S" below.
+# Place the word %S in your translation where the name of the folder should appear.
+imapMovingMessages=Symud negeseuon i %S…
+
+# LOCALIZATION NOTE (imapMovingMessage): Do not translate the word "%S" below.
+# Place the word %S in your translation where the name of the folder should appear.
+imapMovingMessage=Symud neges i %S…
+
+# LOCALIZATION NOTE (imapCopyingMessages): Do not translate the word "%S" below.
+# Place the word %S in your translation where the name of the folder should appear.
+imapCopyingMessages=Copïo negeseuon i %S…
+
+# LOCALIZATION NOTE (imapCopyingMessage): Do not translate the word "%S" below.
+# Place the word %S in your translation where the name of the folder should appear.
+imapCopyingMessage=Copïo neges i %S…
+
+# LOCALIZATION NOTE (imapFolderReceivingMessageOf3): Do not translate the words "%1$S", "%2$S", and "%3$S" below.
+# Place the word %1$S in your translation where the number of the message being downloaded should appear.
+# Place the word %2$S in your translation where the total number of messages to be downloaded should appear.
+# Place the word %3$S in your translation where the name of the folder being processed should appear.
+# Note: The account name and separators (e.g. colon, space) are automatically added to the status message.
+# Example: "Juan's Account: Downloading message 100 of 1000 in Sent…"
+imapFolderReceivingMessageOf3=Llwytho %1$S neges i lawr o %2$S yn %3$S…
+
+# LOCALIZATION NOTE (imapDiscoveringMailbox): Do not translate the word "%S" below.
+# Place the word %S in your translation where the name of the folder should appear.
+imapDiscoveringMailbox=Wedi canfod ffolder: %S
+
+# LOCALIZATION NOTE (imapEnterServerPasswordPrompt): Do not translate the words %1$S and %2$S below.
+# Place the word %1$S in your translation where the username should appear.
+# Place the word %2$S in your translation where the servername should appear.
+imapEnterServerPasswordPrompt=Rhowch eich cyfrinair ar gyfer %1$S ar %2$S:
+
+# LOCALIZATION NOTE (imapServerNotImap4): Do not translate the word "IMAP4" below.
+imapServerNotImap4=Nid yw'r gweinydd e-bost %S yn weinydd e-bost IMAP4.
+
+# This is intentionally left blank.
+imapDone=
+
+# LOCALIZATION NOTE (imapEnterPasswordPromptTitleWithUsername): Do not translate the
+# word %1$S. Place the word %1$S where the user name should appear.
+imapEnterPasswordPromptTitleWithUsername=Rhowch eich cyfrinair ar gyfer %1$S
+
+imapUnknownHostError=Methwyd cysylltu â gweinydd %S.
+imapOAuth2Error=Methiant dilysu wrth gysylltu â gweinydd %S.
+
+imapConnectionRefusedError=Methu cysylltu â gweinydd e-bost %S; gwrthodwyd y cysylltiad.
+
+imapNetTimeoutError=Cyfnod cyswllt i weinydd %S wedi dod i ben.
+
+imapTlsError=Digwyddodd gwall TLS nad oedd modd ei ddiystyru. Mae gwall ysgwyd llaw neu, yn ôl pob tebyg, y fersiwn neu'r dystysgrif TLS sy'n cael ei ddefnyddio gan weinydd %S yn anghydnaws.
+
+# Status - no messages to download
+imapNoNewMessages=Nid oes negeseuon newydd ar y gweinydd.
+
+imapDefaultAccountName=E-bost ar gyfer %S
+
+imapSpecialChar2=Mae nod %S wedi ei neilltuo ar y gweinydd imap hwn. Dewiswch enw arall. 
+
+imapPersonalSharedFolderTypeName=Ffolder Personol
+
+imapPublicFolderTypeName=Ffolder Cyhoeddus
+
+imapOtherUsersFolderTypeName=Ffolder Defnyddiwr Arall
+
+imapPersonalFolderTypeDescription=Ffolder e-bost personol.  Nid yw'n cael ei rhannu.
+
+imapPersonalSharedFolderTypeDescription=Ffolder e-bost personol yw hwn.  Mae,n cael ei rhannu.
+
+imapPublicFolderTypeDescription=Ffolder cyhoeddus yw hwn.
+
+imapOtherUsersFolderTypeDescription=Mae hwn yn ffolder e-bost sy'n cael ei rannu gan ddefnyddiwr '%S'.
+
+imapAclFullRights=Rheolaeth Lawn
+
+imapAclLookupRight=Chwilio
+
+imapAclReadRight=Darllen
+
+imapAclSeenRight=Gosod Cyflwr Darllen/Heb ei Ddarllen
+
+imapAclWriteRight=Ysgrifennu
+
+imapAclInsertRight=Mewnosod (Copïo i)
+
+imapAclPostRight=Cofnodi
+
+imapAclCreateRight=Creu Is-ffolder
+
+imapAclDeleteRight=Dileu Negeseuon
+
+imapAclAdministerRight=Gweinyddu Ffolder
+
+imapServerDoesntSupportAcl=Nid yw'r gweinydd yn cynnal ffolderi wedi'u rhannu.
+
+imapAclExpungeRight=Dileu
+
+imapServerDisconnected= Mae gweinydd %S wedi datgysylltu. Efallai bod y gweinydd yn wallus neu fod anhawster gyda'r rhwydwaith.
+
+# LOCALIZATION NOTE (autoSubscribeText): %1$S is the imap folder.
+imapSubscribePrompt=Hoffech chi danysgrifio i %1$S?
+
+imapServerDroppedConnection=Methu cysylltu â'ch gweinydd IMAP. Efallai eich bod wedi mynd dros yr uchafswm o gysylltiadau âr gweinydd hwn. Os felly, defnyddiwch ddeialog Gosodiadau Gweinydd IMAP Uwch i leihau'r nifer o gysylltiadau storiwyd.
+
+# This will occur when a folder that has never been imap selected or opened
+# (left-clicked) is first right-clicked to access quota properties.
+imapQuotaStatusFolderNotOpen=Nid oes gwybodaeth cwota ar gael am nad yw'r ffolder ar agor.
+
+# The imap capability response reports that QUOTA is not supported.
+imapQuotaStatusNotSupported=Nid yw'r gweinydd yn cynnal cwotâu.
+
+# The getqutaroot command succeeded but reported no quota information.
+imapQuotaStatusNoQuota2=Nid yw'r ffolder hon yn adrodd am unrhyw wybodaeth gwota.
+
+# Folder properties were requested by the user (right-click) before the getquotaroot
+# command was sent.
+imapQuotaStatusInProgress=Nid yw gwybodaeth gwota ar gael eto.
+
+# Out of memory
+imapOutOfMemory=Dim cof ar ôl gan y rhaglen.
+
+# LOCALIZATION NOTE (imapCopyingMessageOf2): Do not translate the word "%S" below.
+# Place the word %3$S in your translation where the name of the destination folder should appear.
+# Place the word %1$S where the currently copying message should appear.
+# Place the word %2$S where the total number of messages should appear.
+imapCopyingMessageOf2=Copïo neges %1$S o %2$S i %3$S…
+
+# LOCALIZATION NOTE (imapMoveFolderToTrash): Do not translate the word %S below.
+# "%S" is the the name of the folder.
+imapMoveFolderToTrash=Ydych chi'n siŵr eich bod am ddileu ffolder '%S'?
+
+# LOCALIZATION NOTE (imapDeleteNoTrash): Do not translate the word %S below.
+# "%S" is the the name of the folder.
+imapDeleteNoTrash=Nid yw dileu'r ffolder hwn yn annileadwy a bydd yn dileu'r holl negeseuon sydd o'i fewn a'r is-ffolderi. Ydych chi'n siŵr eich bod am ddileu ffolder '%S'?
+
+imapDeleteFolderDialogTitle=Dileu Ffolder
+
+imapDeleteFolderButtonLabel=&Dileu Ffolder
+
+# LOCALIZATION NOTE (imapAuthChangeEncryptToPlainSSL): %S is the server hostname
+imapAuthChangeEncryptToPlainSSL=Nid yw gweinydd IMAP %S i weld yn cynnal cyfrineiriau wedi eu hamgryptio. Os ydych newydd osod y cyfrif, ceisiwch newid i 'Cyfrinair arferol' fel y 'Dull Dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau Gweinydd'. Os oedd arfer a gweithio a nawr yn methu'n sydyn, cysylltwch â'ch gweinyddwr e-bost neu eich darparwr.
+
+# LOCALIZATION NOTE (imapAuthChangePlainToEncrypt): %S is the server hostname
+imapAuthChangePlainToEncrypt=Nid yw gweinydd IMAP %S yn caniatáu cyfrineiriau testun plaen. Ceisiwch newid i 'Cyfrinair wedi ei hamgryptio' fel y 'Dull Dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd'.
+
+# LOCALIZATION NOTE (imapAuthChangeEncryptToPlainNoSSL): %S is the server hostname
+imapAuthChangeEncryptToPlainNoSSL=Nid yw gweinydd IMAP %S i weld yn cynnal cyfrineiriau wedi'u hamgryptio. Os ydych newydd osod y cyfrif, ceisiwch newid i 'Cyfrinair, trosglwyddo'n anniogel' fel y 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd'. Os oedd arfer gweithio a nawr yn methu'n sydyn, cysylltwch â'ch gweinyddwr e-bost neu eich darparwr.
+
+# LOCALIZATION NOTE (imapAuthMechNotSupported): %S is the server hostname
+imapAuthMechNotSupported=Nid yw gweinydd IMAP %S yn cynnal y dull dilysu yma. Newidiwch y 'Dull Dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd'.
+
+# LOCALIZATION NOTE (imapAuthGssapiFailed): %S is the server hostname
+imapAuthGssapiFailed=Nid yw'r tocyn Kerberos/GSSAPI wedi'i dderbyn gan y gweinydd IMAP %S. Gwiriwch eich bod wedi mewngofnodi i gylch Kerberos/GSSAPI.
+
+# LOCALIZATION NOTE (imapServerCommandFailed):
+# Place the word %1$S in your translation where the name of the account name should appear.
+# Place the word %2$S in your translation where the server response should appear.
+imapServerCommandFailed=Nid yw'r gorchymyn cyfredol wedi llwyddo. Ymateb gweinydd e-bost cyfrif %1$S oedd: %2$S\u0020
+
+# LOCALIZATION NOTE (imapFolderCommandFailed): Do not translate the word %S below.
+# Place the word %1$S in your translation where the name of the account should appear.
+# Place the word %2$S in your translation where the name of the folder should appear.
+# Place the word %3$S in your translation where the server response should appear.
+imapFolderCommandFailed=Nid oedd y weithred gyfredol ar '%2$S' yn llwyddiant. Ymateb gweinydd e-bost cyfrif %1$S oedd: %3$S
+
+# LOCALIZATION NOTE (imapServerAlert):
+# Place the word %1$S in your translation where the name of the account should appear.
+# Place the word %2$S in your translation where the alert from the server should appear.
+imapServerAlert=Rhybudd o gyfrif %1$S: %2$S
diff --git a/l10n-cy/mail/chrome/messenger/importDialog.dtd b/l10n-cy/mail/chrome/messenger/importDialog.dtd
new file mode 100644
index 0000000000..1b9dcf9661
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/importDialog.dtd
@@ -0,0 +1,48 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--
+LOCALIZATION NOTE : 'Communicator 4.x' is the used for previous versions of
+Netscape Communicator, Please translate using the brandname in respective
+languages for Netscape Communicator 4 releases.
+LOCALIZATION NOTE : Do not translate any of the occurrences of the word
+"&brandShortName;" below.
+-->
+
+<!ENTITY importDialog.windowTitle "Mewnforio">
+<!ENTITY importAll.label          "Mewnforio Popeth">
+<!ENTITY importAll.accesskey      "P">
+<!ENTITY importMail.label         "E-bost">
+<!ENTITY importMail.accesskey     "E">
+<!ENTITY importFeeds.label        "Tanysgrifiad Llif">
+<!ENTITY importFeeds.accesskey    "T">
+<!ENTITY importAddressbook.label  "Llyfrau Cyfeiriadau">
+<!ENTITY importAddressbook.accesskey "L">
+<!ENTITY importSettings.label     "Gosodiadau">
+<!ENTITY importSettings.accesskey "G">
+<!ENTITY importFilters.label      "Hidlau">
+<!ENTITY importFilters.accesskey  "H">
+
+<!ENTITY importTitle.label        "Dewin Mewnforio E-bost &brandShortName;">
+<!ENTITY importShortDesc.label    "Mewnforio E-bost a Llyfrau Cyfeiriadau, Gosodiadau a Hidlau o raglenni eraill">
+
+<!ENTITY importDescription1.label "Bydd y dewin yn mewnforio negeseuon e-bost, dewisiadau cofnodion llyfrau cyfeiriadau a/neu hidlau o raglenni e-bost eraill ac ar fformat llyfr cyfeiriadau cyffredin i mewn i &brandShortName;.">
+<!ENTITY importDescription2.label "Unwaith y byddant wedi'u mewnforio bydd modd cael mynediad atynt o fewn &brandShortName;.">
+
+<!ENTITY selectDescription.label  "Dewiswch y math o ffeil i'w mewnforio:">
+<!ENTITY selectDescriptionB.label "Dewiswch gyfrif cyfredol neu greu cyfrif newydd:">
+<!ENTITY selectDescription.accesskey "f">
+<!ENTITY acctName.label           "Enw:">
+<!ENTITY acctName.accesskey       "E">
+<!ENTITY noModulesFound.label     "Dim rhaglen na ffeil i fewnforio data ohoni wedi ei ganfod.">
+
+<!ENTITY back.label               "&lt; Nôl">
+<!ENTITY forward.label            "Nesaf &gt;">
+<!ENTITY finish.label             "Gorffen">
+<!ENTITY cancel.label             "Diddymu">
+
+<!ENTITY select.label             "neu ddewis y math o ddeunydd i'w fewnforio:">
+
+<!ENTITY title.label              "Teitl">
+<!ENTITY processing.label         "Mewnforio…">
diff --git a/l10n-cy/mail/chrome/messenger/importMsgs.properties b/l10n-cy/mail/chrome/messenger/importMsgs.properties
new file mode 100644
index 0000000000..ab7c517e95
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/importMsgs.properties
@@ -0,0 +1,307 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The following are used by the import code to display status/error 
+# and informational messages
+
+# The following are used by the import code to display status/error
+# and informational messages
+
+# Success message when no address books are found to import
+## @name IMPORT_NO_ADDRBOOKS
+## @loc None
+2000=Heb ganfod llyfrau cyfeiriadau i'w mewnforio.
+
+# Error: Address book import not intialized		
+## @name IMPORT_ERROR_AB_NOTINITIALIZED
+## @loc None
+2001=Methu mewnforio llyfrau cyfeiriadau: gwall ymgychwyn.
+
+# Error: Unable to create the import thread
+## @name IMPORT_ERROR_AB_NOTHREAD
+## @loc None
+2002=Methu mewnforio llyfrau cyfeiriadau: methu creu edefyn mewnforio.
+
+# Error: Unable to create the import thread
+## @name IMPORT_ERROR_GETABOOK
+## @loc None
+# LOCALIZATION NOTE (Error 2003): Do not translate the word "%S" below.
+2003=Gwall wrth fewnforio %S: methu creu llyfr cyfeiriadau.
+
+# Success message when no mailboxes are found to import
+## @name IMPORT_NO_MAILBOXES
+## @loc None
+2004=Dim blychau e-bost wediu canfod i'w mewnforio
+
+# Error: Mailbox import not intialized		
+## @name IMPORT_ERROR_MB_NOTINITIALIZED
+## @loc None
+2005=Methu mewnforio blychau e-bost, gwall ymgychwyn
+
+# Error: Unable to create the import thread
+## @name IMPORT_ERROR_MB_NOTHREAD
+## @loc None
+2006=Methu mewnforio blychau e-bost, methu creu edefyn mewnforio
+
+# Error: Unable to create the proxy object for importing mailboxes
+## @name IMPORT_ERROR_MB_NOPROXY
+## @loc None
+2007=Methu mewnforio blychau e-bost, methu creu gwrthrych dirprwyol ar gyfer cyrchfan blychau e-bost
+
+# Error: Error creating destination mailboxes
+## @name IMPORT_ERROR_MB_FINDCHILD
+## @loc None
+# LOCALIZATION NOTE (Error 2008): Do not translate the word "%S" below.
+# Place %S in your translation where the name of the mailbox should appear.
+2008=Gwall wrth greu blychau e-bost cyrchfan, methu canfod blwch %S
+
+# Error: Error creating destination mailboxes
+## @name IMPORT_ERROR_MB_CREATE
+## @loc None
+# LOCALIZATION NOTE (Error 2009): Do not translate the word "%S" below.
+# Place %S in your translation where the name of the mailbox should appear.
+2009=Gwall wrth fewnforio blwch e-bost %S, methu creu blwch e-bost cyrchfan
+
+# Error: No destination folder to import mailboxes
+## @name IMPORT_ERROR_MB_NODESTFOLDER
+## @loc None
+2010=Methu creu cyfrif i fewnforio iddo
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC_START
+## @loc None
+2100=Enw Cyntaf
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2101=Enw Olaf
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2102=Enw Dangos
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2103=Llysenw
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2104=Prif E-bost
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2105=E-bost Eilradd
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2106=Rhif Ffôn Gwaith
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2107=Rhif Ffôn Cartref
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2108=Rhif Ffacs
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2109=Rhif Swnyn
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2110=Rhif Ffôn Symudol
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2111=Cyfeiriad Cartref
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2112=Cyfeiriad Cartref 2
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2113=Tref/Dinas Cartref
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2114=Sir/Talaith Cartref
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2115=Cod Post Cartref
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2116=Gwlad Cartref
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2117=Cyfeiriad Gwaith
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2118=Cyfeiriad Gwaith 2
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2119=Tref/Dinas Gwaith
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2120=Sir/Talaith Gwaith
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2121=Cod Post Gwaith
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2122=Gwlad Gwaith
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2123=Teitl Swydd
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2124=Adran
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2125=Corff
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2126=Tudalen Gwe 1
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2127=Tudalen Gwe 2
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2128=Blwyddyn Geni
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2129=Mis Geni
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2130=Diwrnod Geni
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2131=Cyfaddasu 1
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2132=Cyfaddasu 2
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2133=Cyfaddasu 3
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2134=Cyfaddasu 4
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC
+## @loc None
+2135=Nodiadau
+
+# Description: Address book field name
+## @name IMPORT_FIELD_DESC_END
+## @loc None
+2136=Enw Sgrin
+
+#Error strings
+ImportAlreadyInProgress=Mae gweithred mewnforio yn digwydd ar hyn o bryd, rhowch gynnig arall pan fydd y mewnforio cyfredol wedi dod i ben.
+
+#Error strings for settings import
+ImportSettingsBadModule=Methu llwytho modiwl gosodiadau
+ImportSettingsNotFound=Methu canfod gosodiadau.  Gwiriwch fod y rhaglen wedi'i osod ar y peiriant.
+ImportSettingsFailed=Digwyddodd gwall wrth fewnforio gosodiadau.  Mae'n bosib i rai ac efallai'r cyfan fethu cael eu mewnforio.
+# LOCALIZATION NOTE : Do not translate the word "%S" below.
+ImportSettingsSuccess=Gosodiadau wedi'u mewnforio o %S
+
+#Error string for mail import
+ImportMailBadModule=Methu llwytho modiwl mewnforio e-bost
+ImportMailNotFound=Digwyddodd gwall wrth fewnforio gosodiadau.  Mae'n bosib i rai ac efallai'r cyfan fethu cael eu mewnforio.
+ImportEmptyAddressBook=Methu mewnforio llyfr cyfeiriadau gwag %S.
+# LOCALIZATION NOTE: Do not translate the word "%S" below.
+ImportMailFailed=Digwyddodd gwall wrth fewnforio e-bost o %S
+# LOCALIZATION NOTE: Do not translate the word "%S" below.
+ImportMailSuccess=E-bost wedi'i fewnforio'n llwyddiannus o %S
+
+# Error string for address import
+ImportAddressBadModule=Methu llwytho modiwl mewnforio llyfr cyfeiriadau.
+ImportAddressNotFound=Methu canfod unrhyw lyfr cyfeiriadau i'w fewnforio.  Gwiriwch fod y rhaglen neu'r fformat wedi'i osod yn gywir ar y peiriant.
+# LOCALIZATION NOTE : Do not translate the word "%S" below.
+ImportAddressFailed=Digwyddodd gwall wrth fewnforio cyfeiriadau o %S.
+# LOCALIZATION NOTE : Do not translate the word "%S" below.
+ImportAddressSuccess=Cyfeiriadau wedi'u mewnforio'n llwyddiannus o %S.
+
+# Error string for filters import
+ImportFiltersBadModule=Methu llwytho modiwl mewnforio hidlau.
+# LOCALIZATION NOTE : The %S will get replaced by the name of the import module.
+ImportFiltersFailed=Digwyddodd gwall wrth fewnforio hidlau o %S.
+# LOCALIZATION NOTE : The %S will get replaced by the name of the import module.
+ImportFiltersSuccess=Hidlau wedi'u mewnforio'n llwyddiannus o %S.
+# LOCALIZATION NOTE : The %S will get replaced by the name of the import module.
+ImportFiltersPartial=Hidlau wedi'u mewnforio'n rhannol o %S.  Rhybudd isod:
+
+#Progress strings
+# LOCALIZATION NOTE : Do not translate the word "%S" below.
+MailProgressMeterText=Trosi blychau e-bost o %S
+# LOCALIZATION NOTE : Do not translate the word "%S" below.
+AddrProgressMeterText=Trosi llyfrau cyfeiriadau o %S
+
+#Import file dialog strings
+ImportSelectSettings=Dewiswch ffeil gosodiadau
+ImportSelectMailDir=Dewiswch gyfeiriadur e-bost
+ImportSelectAddrDir=Dewiswch gyfeiriadur llyfr cyfeiriadau
+ImportSelectAddrFile=Dewiswch ffeil llyfr cyfeiriadau
+
+# Folder Names for imported Mail
+DefaultFolderName=E-bost wedi'i Fewnforio
+# LOCALIZATION NOTE: Do not translate the word "%S" below.
+ImportModuleFolderName=Mewnforio %S
diff --git a/l10n-cy/mail/chrome/messenger/joinChat.dtd b/l10n-cy/mail/chrome/messenger/joinChat.dtd
new file mode 100644
index 0000000000..ff1971209f
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/joinChat.dtd
@@ -0,0 +1,10 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY joinChatWindow.title           "Ymuno â sgwrs">
+<!ENTITY name.label                     "Ystafell">
+<!ENTITY optional.label                 "(dewisol)">
+<!ENTITY account.label                  "Cyfrif">
+<!ENTITY autojoin.label                 "Awto-ymuno â'r Ystafell Sgwrsio">
+<!ENTITY autojoin.accesskey             "A">
diff --git a/l10n-cy/mail/chrome/messenger/junkLog.dtd b/l10n-cy/mail/chrome/messenger/junkLog.dtd
new file mode 100644
index 0000000000..96e6d35a7c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/junkLog.dtd
@@ -0,0 +1,10 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY adaptiveJunkLog.title "Cofnod Sbam Addasol">
+<!ENTITY adaptiveJunkLogInfo.label "Cofnod gweithgaredd rheoli e-bost sbam addasol.">
+<!ENTITY clearLog.label "Clirio'r Cofnod">
+<!ENTITY clearLog.accesskey "l">
+<!ENTITY closeLog.label "Cau">
+<!ENTITY closeLog.accesskey "a">
diff --git a/l10n-cy/mail/chrome/messenger/localMsgs.properties b/l10n-cy/mail/chrome/messenger/localMsgs.properties
new file mode 100644
index 0000000000..d82a0bf89c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/localMsgs.properties
@@ -0,0 +1,140 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the local mail code to display progress/status/error messages
+#
+
+# LOCALIZATION NOTE(pop3ErrorDialogTitle): Do not translate the word "%S"
+# below. Place the word %S where the account name should appear.
+pop3ErrorDialogTitle=Gwall gyda chyfrif %S
+
+# LOCALIZATION NOTE (pop3EnterPasswordPromptTitleWithUsername): Do not translate the
+# word %1$S. Place the word %1$S where the user name should appear.
+pop3EnterPasswordPromptTitleWithUsername=Rhowch eich cyfrinair ar gyfer %1$S
+
+# LOCALIZATION NOTE(pop3EnterPasswordPrompt): Do not translate the words "%1$S"
+# and "%2$S" below. Place the word %1$S where the user name should appear, and
+# %2$S where the host name should appear.
+pop3EnterPasswordPrompt=Cyflwyno eich cyfrinair ar gyfer %1$S ar %2$S:
+
+# LOCALIZATION NOTE(pop3PreviouslyEnteredPasswordIsInvalidPrompt): Do not
+# translate the words "%1$S" and "%2$S" below. Place the word %1$S where the
+# user name should appear, and %2$S where the host name should appear.
+pop3PreviouslyEnteredPasswordIsInvalidPrompt=Rhoi cyfrinair newydd i ddefnyddiwr %1$S ar %2$S:
+
+# Status - Downloading message n of m
+# LOCALIZATION NOTE (receivingMessages): Do not translate %1$S or %2$S in the following lines.
+# Place the word %1$S where the number of messages downloaded so far should appear.
+# Place the word %2$S where the total number of messages to receive should appear;
+receivingMessages=Llwytho i lawr neges %1$S o %2$S…
+
+# Status - connecting to host
+hostContact=Wedi cysylltu â'r gwesteiwr, anfon manylion mewngofnodi…
+
+# Status - no messages to download
+noNewMessages=Does dim negeseuon newydd.
+
+# Status - messages received after the download
+#LOCALIZATION NOTE : Do not translate %1$S or %2$S in the following line.
+# %1$S will receive the number of messages received
+# %2$S will receive the total number of messages
+receivedMsgs=Mae %1$S o %2$S neges wedi eu derbyn
+
+# Status - parsing folder
+#LOCALIZATION NOTE (buildingSummary): Do not translate %S in the following line.
+# Place the word %S where the name of the mailbox should appear
+buildingSummary=Adeiladu ffeil crynodeb ar gyfer %S…
+
+# Status - parsing folder
+localStatusDocumentDone=Gorffen
+
+# Status - pop3 server error
+#LOCALIZATION NOTE (pop3ServerError): Do not translate POP3 in the following line.
+pop3ServerError=Digwyddodd gwall gyda gweinydd e-bost POP3.
+
+# Status - pop3 user name failed
+pop3UsernameFailure=Methwyd anfon yr enw defnyddiwr.
+
+# Status - password failed
+#LOCALIZATION NOTE (pop3PasswordFailed): Do not translate "%1$S" below.
+# Place the word %1$S where the user name should appear.
+pop3PasswordFailed=Methodd anfon cyfrinair defnyddiwr %1$S.
+
+# Status - write error occurred
+pop3MessageWriteError=Methu ysgrifennu'r e-bost i'r blwch e-bost. Gwnewch yn siŵr fod y system ffeiliau yn caniatáu hawliau ysgrifennu a bod gennych ddigon o le ar ddisg i gopïo i'r blwch e-bost.
+
+# Status - retr failure from the server
+pop3RetrFailure=Methodd y gorchymyn RETR. Gwall estyn y neges.
+
+# Status - password undefined
+pop3PasswordUndefined=Gwall wrth estyn cyfrinair e-bost.
+
+# Status - username undefined
+pop3UsernameUndefined=Nid ydych wedi darparu enw defnyddiwr ar gyfer y gweinydd.  Darparwch un yn newislen gosod y cyfrif a cheisio eto.
+
+# Status - list failure
+pop3ListFailure=Methodd y gorchymyn LIST. Gwall canfod enw a maint y neges.
+
+# Status - delete error
+pop3DeleFailure=Methodd y gorchymyn DELE. Gwall wrth farcio neges wedi'i ddileu.
+
+# Status - stat failed
+pop3StatFail=Methodd y gorchymyn STAT. Gwall canfod rhif y neges a'u maint.
+
+#LOCALIZATION NOTE (pop3ServerSaid): Do not remove the leading space during translation.
+pop3ServerSaid= Ymateb gweinydd e-bost %S oedd:\u0020
+
+#LOCALIZATION NOTE (pop3TempServerError): %S is where the POP3 server name will appear.
+pop3TempServerError=Gwall dros dro o %S wrth adfer negeseuon newydd. \
+Bydd y weithred yn cael ei dynnu yn y gwiriad nesaf am negeseuon newydd.
+
+copyingMessagesStatus=Copïo %S o %S neges i %S
+
+movingMessagesStatus=Symud %S o %S neges i %S
+
+# Status - pop3 server or folder busy
+# LOCALIZATION NOTE (pop3ServerBusy): Do not translate the word "%S" below.
+# Place %S where the account name should appear.
+pop3ServerBusy=Mae cyfrif %S yn cael ei brosesu. Arhoswch i'r prosesu gwblhau cyn derbyn eich negeseuon.
+
+pop3TmpDownloadError=Bu gwall wrth lwytho i lawr y neges ganlynol:   \nOddi wrth: %S\n   Pwnc: %S\n Gall y neges gynnwys firws neu does dim digon o le ar y disg. Hepgor y neges?
+
+# Status - the server doesn't support UIDL…
+# LOCALIZATION NOTE(pop3ServerDoesNotSupportUidlEtc): The following sentence should be translated in this way:
+# Do not translate "POP3"
+# Do not translate "%S". Place %S in your translation where the name of the server should appear.
+# Do not translate "UIDL"
+pop3ServerDoesNotSupportUidlEtc=Nid yw'r gweinydd POP3 (%S) yn cynnal UIDL na XTND XLST, sydd ei angen i weithredu dewisiadau ``Gadael ar y Gweinydd", ``Maint Mwyaf Neges" neu ``Estyn Pennyn yn Unig". I lwytho eich e-bost i lawr diffoddwch y dewisiadau hyn Gosodiadau Gweinydd eich gweinydd e-bost yn ffenestr Gosodiadau Cyfrif.
+
+# Status - the server doesn't support the top command
+# LOCALIZATION NOTE(pop3ServerDoesNotSupportTopCommand): The following sentence should be translated in this way:
+# Do not translate "POP3"
+# Do not translate "%S". Place %S in your translation where the name of the server should appear.
+# Do not translate "TOP"
+pop3ServerDoesNotSupportTopCommand=Nid yw'r gweinydd POP3 (%S) yn cynnal y gorchymyn TOP. Heb gefnogaeth y gweinydd ar gyfer hwn nid ydym yn gallu gweithredu dewisiadau ``Maint Mwyaf Neges" neu ``Estyn Pennyn yn Unig".  Mae'r dewis wedi ei anablu a bydd negeseuon yn cael eu llwytho i lawr beth bynnag yw eu maint.
+
+nsErrorCouldNotConnectViaTls=Methu creu cysylltiad TLS gyda gweinydd POP3. Gall fod bod y gweinydd wedi methu neu heb ei ffurfweddu'n gywir. Gwiriwch fod gosodiadau eich cyfrif E-bost/Newyddion yn gywir a cheisiwch eto.
+
+# LOCALIZATION NOTE (pop3MoveFolderToTrash): Do not translate the word %S below.
+# "%S" is the the name of the folder.
+pop3MoveFolderToTrash=Ydych chi'n siŵr eich bod am ddileu'r ffolder '%S'?
+
+pop3DeleteFolderDialogTitle=Dileu Ffolder
+
+pop3DeleteFolderButtonLabel=&Dileu Ffolder
+
+pop3AuthInternalError=Gwall cyflwr mewnol yn ystod dilysu gweinydd POP3. Gwall mewnol annisgwyl o fewn y rhaglen yw hwn, anfonwch adroddiad gwall.
+
+pop3AuthChangeEncryptToPlainNoSSL=Nid yw'r gweinydd e-bost POP3 yma i weld yn cynnal cyfrineiriau amgryptiedig. Os ydych newydd greu cyfrif, ceisiwch hewid i 'Cyfrinair, trosglwyddo anniogel' fel y 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd'. Os oedd arfer gweithio ond nawr yn methu, mae hwn yn sefyllfa gyffredin lle gall rhywun ddwyn eich cyfrinair.
+
+pop3AuthChangeEncryptToPlainSSL=Nid yw'r gweinydd e-bost POP3 yma i weld yn cynnal cyfrineiriau amgryptiedig. Os ydych newydd greu cyfrif, ceisiwch newid i 'Cyfrinair arferol' fel y 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd'. Os oedd arfer gweithio ond nawr yn methu, cysylltwch â'ch gweinyddwr e-bost neu ddarparwr.
+
+pop3AuthChangePlainToEncrypt=Nid yw'r gweinydd e-bost POP3 yma caniatáu cyfrineiriau testun plaen. Ceisiwch newid i 'Cyfrinair amgryptiedig' fel y 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd'.
+
+# Authentication server caps and pref don't match
+pop3AuthMechNotSupported=Nid yw'r gweinydd yn cynnal y dull dilysu yma. Newidiwch y 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd'.
+
+# Status - Could not log in to GSSAPI, and it was the only method
+pop3GssapiFailure=Nid yw'r tocyn Kerberos/GSSAPI wedi'i dderbyn gan y gweinydd POP. Gwiriwch eich bod wedi eich mewngofnodi i'r cylch Kerberos/GSSAPI.
diff --git a/l10n-cy/mail/chrome/messenger/mailEditorOverlay.dtd b/l10n-cy/mail/chrome/messenger/mailEditorOverlay.dtd
new file mode 100644
index 0000000000..64728f3361
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/mailEditorOverlay.dtd
@@ -0,0 +1,6 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY sendPage.label                   "Anfon y Dudalen…">
+<!ENTITY sendPage.accesskey               "A">
diff --git a/l10n-cy/mail/chrome/messenger/mailOverlay.dtd b/l10n-cy/mail/chrome/messenger/mailOverlay.dtd
new file mode 100644
index 0000000000..5b7c0eab37
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/mailOverlay.dtd
@@ -0,0 +1,11 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY  newMessageCmd2.key              "N">
+<!ENTITY  newMessageCmd.key               "M">
+<!ENTITY  newMessageCmd.label             "Neges">
+<!ENTITY  newMessageCmd.accesskey         "N">
+ 
+<!ENTITY  newContactCmd.label             "Cysylltiad Llyfr Cyfeiriadau…">
+<!ENTITY  newContactCmd.accesskey         "C">
diff --git a/l10n-cy/mail/chrome/messenger/mailViewList.dtd b/l10n-cy/mail/chrome/messenger/mailViewList.dtd
new file mode 100644
index 0000000000..f2f599b051
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/mailViewList.dtd
@@ -0,0 +1,9 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE msgViewPickerOverlay.dtd UI for showing various views on a folder -->
+
+
+<!ENTITY mailViewListTitle.label "Cyfaddasu Golwg Negeseuon">
+
diff --git a/l10n-cy/mail/chrome/messenger/mailViewSetup.dtd b/l10n-cy/mail/chrome/messenger/mailViewSetup.dtd
new file mode 100644
index 0000000000..49b1a15a8d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/mailViewSetup.dtd
@@ -0,0 +1,12 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE msgViewPickerOverlay.dtd UI for showing various views on a folder -->
+
+
+<!ENTITY mailViewSetupTitle.label "Gosod Golwg Negeseuon">
+<!ENTITY mailViewHeading.label "Enw golwg neges:">
+<!ENTITY mailViewHeading.accesskey "E">
+<!ENTITY searchTermCaption.label "Pan fyddwch yn dewis y golwg hwn, dangos dim ond negeseuon sydd:">
+
diff --git a/l10n-cy/mail/chrome/messenger/mailviews.properties b/l10n-cy/mail/chrome/messenger/mailviews.properties
new file mode 100644
index 0000000000..380ce9ec25
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/mailviews.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# Mail Views
+#
+
+mailViewPeopleIKnow=Pobl Rwy'n Nabod
+mailViewRecentMail=E-bost Diweddar
+mailViewLastFiveDays=5 Diwrnod Diwethaf
+mailViewNotJunk=Nid Sbam
+mailViewHasAttachments=Atodiadau Ynghlwm
diff --git a/l10n-cy/mail/chrome/messenger/markByDate.dtd b/l10n-cy/mail/chrome/messenger/markByDate.dtd
new file mode 100644
index 0000000000..6b5772f28e
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/markByDate.dtd
@@ -0,0 +1,9 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY messageMarkByDate.label "Marcio'r Negeseuon Wedi eu Darllen yn ôl Dyddiad">
+<!ENTITY markByDateLower.label "Marcio'r negeseuon hyn wedi'u darllen ers:">
+<!ENTITY markByDateLower.accesskey "M">
+<!ENTITY markByDateUpper.label "At:">
+<!ENTITY markByDateUpper.accesskey "A">
diff --git a/l10n-cy/mail/chrome/messenger/messenger.dtd b/l10n-cy/mail/chrome/messenger/messenger.dtd
new file mode 100644
index 0000000000..232d557f3a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messenger.dtd
@@ -0,0 +1,945 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY titledefault.label "&brandFullName;">
+<!ENTITY titleSeparator.label " - ">
+
+<!-- File Menu -->
+<!ENTITY newFolderCmd.label "Ffolder…">
+<!ENTITY newFolderCmd.accesskey "F">
+<!ENTITY closeTabCmd2.label "Cau'r Tab">
+<!ENTITY closeTabCmd2.accesskey "C">
+<!ENTITY closeOtherTabsCmd2.label "Cau Tabiau Eraill">
+<!ENTITY closeOtherTabsCmd2.accesskey "E">
+<!ENTITY recentlyClosedTabsCmd.label "Tabiau Wedi'u Cau'n Ddiweddar">
+<!ENTITY recentlyClosedTabsCmd.accesskey "D">
+
+<!ENTITY undoCloseTabCmd.commandkey "T">
+<!-- LOCALIZATION NOTE (moveToNewWindow.label):
+     Menu option to cause the current tab to be migrated to a new Thunderbird
+     window.
+     -->
+<!ENTITY moveToNewWindow.label "Symud i Ffenestr Newydd">
+<!ENTITY moveToNewWindow.accesskey "S">
+<!ENTITY newVirtualFolderCmd.label "Chwilio a Gadwyd…">
+<!ENTITY newVirtualFolderCmd.accesskey "w">
+<!ENTITY newCreateEmailAccountCmd.label "Estyn Cyfrif E-bost Newydd…">
+<!ENTITY newCreateEmailAccountCmd.accesskey "E">
+<!ENTITY newExistingEmailAccountCmd.label "Cyfrif E-bost Cyfredol…">
+<!ENTITY newExistingEmailAccountCmd.accesskey "C">
+<!ENTITY newIMAccountCmd.label "Cyfrif Sgwrsio…">
+<!ENTITY newIMAccountCmd.accesskey "S">
+<!ENTITY newFeedAccountCmd.label "Cyfrif Llif…">
+<!ENTITY newFeedAccountCmd.accesskey "y">
+<!ENTITY newIMContactCmd.label "Cysylltiad Sgwrsio…">
+<!ENTITY newIMContactCmd.accesskey "S">
+<!ENTITY  newMessageCmd2.key "E">
+<!ENTITY  newMessageCmd.key "N">
+<!ENTITY  newMessageCmd.label "Neges">
+<!ENTITY  newMessageCmd.accesskey "n">
+<!ENTITY  newContactCmd.label "Cysylltiad Llyfr Cyfeiriadau…">
+<!ENTITY  newContactCmd.accesskey "C">
+<!ENTITY openMenuCmd.label "Agor">
+<!ENTITY openMenuCmd.accesskey "A">
+<!ENTITY openMessageFileCmd.label "Agor Neges Wedi'i Chadw…">
+<!ENTITY openMessageFileCmd.accesskey "s">
+<!ENTITY saveAsMenu.label "Cadw Fel">
+<!ENTITY saveAsMenu.accesskey "C">
+<!ENTITY saveAsFileCmd.key "s">
+<!ENTITY saveAsTemplateCmd.label "Templed">
+<!ENTITY saveAsTemplateCmd.accesskey "T">
+<!ENTITY getNewMsgForCmd.label "Estyn Negeseuon Newydd">
+<!ENTITY getNewMsgForCmd.accesskey "E">
+<!ENTITY getAllNewMsgCmdPopupMenu.label "Pob Cyfrif">
+<!ENTITY getAllNewMsgCmdPopupMenu.accesskey "P">
+<!ENTITY getNewMsgCurrentAccountCmdPopupMenu.label "Cyfrif Cyfredol">
+<!ENTITY getNewMsgCurrentAccountCmdPopupMenu.accesskey "y">
+<!ENTITY getNextNMsgCmd2.label "Estyn y Negeseuon Newyddion Nesaf">
+<!ENTITY getNextNMsgCmd2.accesskey "E">
+<!ENTITY sendUnsentCmd.label "Anfon Negeseuon heb eu Hanfon">
+<!ENTITY sendUnsentCmd.accesskey "H">
+<!ENTITY subscribeCmd.label "Tanysgrifio…">
+<!ENTITY subscribeCmd.accesskey "T">
+<!ENTITY deleteFolder.label "Dileu Ffolder">
+<!ENTITY deleteFolder.accesskey "D">
+<!ENTITY renameFolder.label "Ailenwi Ffolder…">
+<!ENTITY renameFolder.accesskey "F">
+<!ENTITY renameFolder.key "VK_F2">
+<!ENTITY compactFolders.label "Cywasgu'r Ffolderi">
+<!ENTITY compactFolders.accesskey "w">
+<!ENTITY emptyTrashCmd.label "Gwagio'r Sbwriel">
+<!ENTITY emptyTrashCmd.accesskey "w">
+<!ENTITY offlineMenu.label "All-lein">
+<!ENTITY offlineMenu.accesskey "l">
+<!ENTITY offlineGoOfflineCmd.label "Gweithio All-lein">
+<!ENTITY offlineGoOfflineCmd.accesskey "w">
+<!ENTITY synchronizeOfflineCmd.label "Llwytho i Lawr/Cydweddu Nawr…">
+<!ENTITY synchronizeOfflineCmd.accesskey "L">
+<!ENTITY settingsOfflineCmd2.label "Gosodiadau All-lein">
+<!ENTITY settingsOfflineCmd2.accesskey "G">
+<!ENTITY downloadSelectedCmd.label "Estyn y Negeseuon Hyn">
+<!ENTITY downloadSelectedCmd.accesskey "H">
+<!ENTITY downloadStarredCmd.label "Estyn Negeseuon Serennog">
+<!ENTITY downloadStarredCmd.accesskey "S">
+<!ENTITY printCmd.label "Argraffu…">
+<!ENTITY printCmd.accesskey "A">
+<!ENTITY printCmd.key "p">
+
+<!-- Edit Menu -->
+<!ENTITY deleteMsgCmd.label "Dileu Neges">
+<!ENTITY deleteMsgCmd.accesskey "N">
+<!ENTITY undeleteMsgCmd.label "Dad-ddileu Neges">
+<!ENTITY undeleteMsgCmd.accesskey "a">
+<!ENTITY deleteMsgsCmd.label "Dileu'r Negeseuon Hyn">
+<!ENTITY deleteMsgsCmd.accesskey "i">
+<!ENTITY undeleteMsgsCmd.label "Dad-ddileu'r Negeseuon Hyn">
+<!ENTITY undeleteMsgsCmd.accesskey "a">
+<!ENTITY deleteFolderCmd.label "Dileu Ffolder">
+<!ENTITY deleteFolderCmd.accesskey "F">
+<!ENTITY unsubscribeNewsgroupCmd.label "Dad-danysgrifio">
+<!ENTITY unsubscribeNewsgroupCmd.accesskey "y">
+<!ENTITY selectMenu.label "Dewis">
+<!ENTITY selectMenu.accesskey "w">
+<!ENTITY all.label "Popeth">
+<!ENTITY all.accesskey "P">
+<!ENTITY selectThreadCmd.label "Edefyn">
+<!ENTITY selectThreadCmd.accesskey "E">
+<!ENTITY selectThreadCmd.key "a">
+<!ENTITY selectFlaggedCmd.label "Negeseuon Serennog">
+<!ENTITY selectFlaggedCmd.accesskey "S">
+<!ENTITY menuFavoriteFolder.label "Hoff Ffolder">
+<!ENTITY menuFavoriteFolder.accesskey "H">
+<!ENTITY folderPropsCmd2.label "Priodweddau">
+<!ENTITY folderPropsFolderCmd2.label "Priodweddau Ffolder">
+<!ENTITY folderPropsNewsgroupCmd2.label "Priodweddau Grŵp Newyddion">
+<!ENTITY folderPropsCmd.accesskey "o">
+<!ENTITY undoDeleteMsgCmd.label "Dadwneud Dileu Negeseuon">
+<!ENTITY redoDeleteMsgCmd.label "Ail-wneud Dileu Neges">
+<!ENTITY undoMoveMsgCmd.label "Dadwneud Symud Neges">
+<!ENTITY redoMoveMsgCmd.label "Ailwneud Symud Neges">
+<!ENTITY undoCopyMsgCmd.label "Dadwneud Copïo Neges">
+<!ENTITY redoCopyMsgCmd.label "Ail-wneud Copïo Neges">
+<!ENTITY undoMarkAllCmd.label "Dadwneud Marcio Pob Un Wedi ei Ddarllen">
+<!ENTITY redoMarkAllCmd.label "Ail-wneud Marcio Popeth Wedi'i Ddarllen">
+<!ENTITY undoDefaultCmd.label "Dadwneud">
+<!ENTITY undoDefaultCmd.accesskey "u">
+<!ENTITY redoDefaultCmd.label "Ailwneud">
+<!ENTITY redoDefaultCmd.accesskey "A">
+
+<!-- View Menu -->
+<!ENTITY menubarCmd.label "Bar Dewislen">
+<!ENTITY menubarCmd.accesskey "D">
+<!ENTITY showMessengerToolbarCmd.label "Bar Offer E-bost">
+<!ENTITY showMessengerToolbarCmd.accesskey "O">
+<!ENTITY customizeToolbar.label "Cyfaddasu…">
+<!ENTITY customizeToolbar.accesskey "C">
+
+<!ENTITY messagePaneLayoutStyle.label "Cynllun">
+<!ENTITY messagePaneLayoutStyle.accesskey "C">
+<!ENTITY messagePaneClassic.label "Golwg Glasurol">
+<!ENTITY messagePaneClassic.accesskey "l">
+<!ENTITY messagePaneWide.label "Golwg Lydan">
+<!ENTITY messagePaneWide.accesskey "L">
+<!ENTITY messagePaneVertical.label "Golwr Fertigol">
+<!ENTITY messagePaneVertical.accesskey "F">
+<!ENTITY showFolderPaneCmd.label "Paen Ffolder">
+<!ENTITY showFolderPaneCmd.accesskey "F">
+<!ENTITY showFolderPaneColsCmd.label "Colofnau Paenau Ffolderi">
+<!ENTITY showFolderPaneColsCmd.accesskey "P">
+<!ENTITY showMessageCmd.label "Paen Neges">
+<!ENTITY showMessageCmd.accesskey "N">
+
+<!ENTITY folderView.label "Ffolderi">
+<!ENTITY folderView.accesskey "F">
+<!ENTITY unifiedFolders.label "Unedig">
+<!ENTITY unifiedFolders.accesskey "U">
+<!ENTITY allFolders.label "Popeth">
+<!ENTITY allFolders.accesskey "P">
+<!ENTITY unreadFolders.label "Heb ei Ddarllen">
+<!ENTITY unreadFolders.accesskey "H">
+<!ENTITY favoriteFolders.label "Ffefryn">
+<!ENTITY favoriteFolders.accesskey "F">
+<!ENTITY recentFolders.label "Diweddar">
+<!ENTITY recentFolders.accesskey "D">
+<!ENTITY compactVersion.label "Golwg Cryno">
+<!ENTITY compactVersion.accesskey "G">
+
+<!-- Sort Menu -->
+<!ENTITY sortMenu.label "Trefnu yn ôl">
+<!ENTITY sortMenu.accesskey "T">
+<!ENTITY sortByDateCmd.label "Dyddiad">
+<!ENTITY sortByDateCmd.accesskey "D">
+<!ENTITY sortByReceivedCmd.label "Derbyn">
+<!ENTITY sortByReceivedCmd.accesskey "e">
+<!ENTITY sortByStarCmd.label "Seren">
+<!ENTITY sortByStarCmd.accesskey "S">
+<!ENTITY sortByAttachmentsCmd.label "Atodiadau">
+<!ENTITY sortByAttachmentsCmd.accesskey "A">
+<!ENTITY sortByPriorityCmd.label "Blaenoriaeth">
+<!ENTITY sortByPriorityCmd.accesskey "B">
+<!ENTITY sortBySizeCmd.label "Maint">
+<!ENTITY sortBySizeCmd.accesskey "M">
+<!ENTITY sortByStatusCmd.label "Statws">
+<!ENTITY sortByStatusCmd.accesskey "S">
+<!ENTITY sortByTagsCmd.label "Tagiau">
+<!ENTITY sortByTagsCmd.accesskey "g">
+<!ENTITY sortByJunkStatusCmd.label "Statws Sbam">
+<!ENTITY sortByJunkStatusCmd.accesskey "S">
+<!ENTITY sortBySubjectCmd.label "Pwnc">
+<!ENTITY sortBySubjectCmd.accesskey "P">
+<!ENTITY sortByFromCmd.label "Oddi wrth">
+<!ENTITY sortByFromCmd.accesskey "O">
+<!ENTITY sortByRecipientCmd.label "Derbynnydd">
+<!ENTITY sortByRecipientCmd.accesskey "D">
+<!ENTITY sortByCorrespondentCmd.label "Cyfathrebwyr">
+<!ENTITY sortByCorrespondentCmd.accesskey "f">
+<!ENTITY sortByUnreadCmd.label "Darllenwyd">
+<!ENTITY sortByUnreadCmd.accesskey "D">
+<!ENTITY sortByOrderReceivedCmd.label "Trefn Derbyn">
+<!ENTITY sortByOrderReceivedCmd.accesskey "T">
+<!ENTITY sortAscending.label "Esgyn">
+<!ENTITY sortAscending.accesskey "E">
+<!ENTITY sortDescending.label "Disgyn">
+<!ENTITY sortDescending.accesskey "D">
+<!ENTITY sortThreaded.label "Edafwyd">
+<!ENTITY sortThreaded.accesskey "d">
+<!ENTITY sortUnthreaded.label "Dim edefyn">
+<!ENTITY sortUnthreaded.accesskey "i">
+<!ENTITY groupBySort.label "Grwpio yn ôl Trefnu">
+<!ENTITY groupBySort.accesskey "G">
+<!ENTITY msgsMenu.label "Negeseuon">
+<!ENTITY msgsMenu.accesskey "N">
+<!ENTITY threads.label "Edafedd">
+<!ENTITY threads.accesskey "d">
+<!ENTITY allMsgsCmd.label "Popeth">
+<!ENTITY allMsgsCmd.accesskey "P">
+<!ENTITY expandAllThreadsCmd.label "Ehangu Pob Edefyn">
+<!ENTITY expandAllThreadsCmd.accesskey "E">
+<!ENTITY expandAllThreadsCmd.key "*">
+<!ENTITY collapseAllThreadsCmd.label "Cau Pob Edefyn">
+<!ENTITY collapseAllThreadsCmd.accesskey "C">
+<!ENTITY collapseAllThreadsCmd.key "\">
+<!ENTITY unreadMsgsCmd.label "Heb ei Ddarllen">
+<!ENTITY unreadMsgsCmd.accesskey "H">
+<!ENTITY threadsWithUnreadCmd.label "Edafedd gyda rhai Heb eu Darllen">
+<!ENTITY threadsWithUnreadCmd.accesskey "H">
+<!ENTITY watchedThreadsWithUnreadCmd.label "Gwylio Edafedd gyda rhai Heb eu Darllen">
+<!ENTITY watchedThreadsWithUnreadCmd.accesskey "G">
+<!ENTITY ignoredThreadsCmd.label "Edafedd Anwybyddwyd">
+<!ENTITY ignoredThreadsCmd.accesskey "n">
+
+<!ENTITY headersMenu.label "Penynnau">
+<!ENTITY headersMenu.accesskey "P">
+<!ENTITY headersAllCmd.label "Popeth">
+<!ENTITY headersAllCmd.accesskey "P">
+<!ENTITY headersNormalCmd.label "Arferol">
+<!ENTITY headersNormalCmd.accesskey "A">
+<!ENTITY bodyMenu.label "Corff y Neges Fel">
+<!ENTITY bodyMenu.accesskey "o">
+<!ENTITY bodyAllowHTML.label "HTML Gwreiddiol">
+<!ENTITY bodyAllowHTML.accesskey "H">
+<!ENTITY bodySanitized.label "HTML Syml">
+<!ENTITY bodySanitized.accesskey "S">
+<!ENTITY bodyAsPlaintext.label "Testun Plaen">
+<!ENTITY bodyAsPlaintext.accesskey "P">
+<!ENTITY bodyAllParts.label "Pob Rhan o'r Corff">
+<!ENTITY bodyAllParts.accesskey "P">
+
+<!ENTITY bodyMenuFeed.label "Corff Neges Llif Fel">
+<!ENTITY bodyMenuFeed.accesskey "L">
+<!ENTITY viewFeedWebPage.label "Tudalen Gwe">
+<!ENTITY viewFeedWebPage.accesskey "G">
+<!ENTITY viewFeedSummary.label "Crynodeb">
+<!ENTITY viewFeedSummary.accesskey "r">
+<!ENTITY viewFeedSummaryFeedPropsPref.label "Fformat Rhagosodedig">
+<!ENTITY viewFeedSummaryFeedPropsPref.accesskey "R">
+
+<!ENTITY viewAttachmentsInlineCmd.label "Dangos Atodiadau Mewnlin">
+<!ENTITY viewAttachmentsInlineCmd.accesskey "D">
+
+<!ENTITY pageSourceCmd.label "Ffynhonnell y Neges">
+<!ENTITY pageSourceCmd.accesskey "F">
+<!ENTITY pageSourceCmd.key "u">
+<!ENTITY getNewMessagesCmd.key "y">
+<!ENTITY getAllNewMessagesCmd.key "Y">
+
+<!-- Search Menu -->
+<!ENTITY findMenu.label "Canfod">
+<!ENTITY findMenu.accesskey "f">
+<!ENTITY findCmd.label "Canfod yn y Neges…">
+<!ENTITY findCmd.accesskey "a">
+<!ENTITY findCmd.key "f">
+<!ENTITY findAgainCmd.label "Canfod Eto">
+<!ENTITY findAgainCmd.accesskey "E">
+<!ENTITY findAgainCmd.key "g">
+<!ENTITY findAgainCmd.key2 "VK_F3">
+<!ENTITY findPrevCmd.key "g">
+<!ENTITY findPrevCmd.key2 "VK_F3">
+<!ENTITY searchMailCmd.label "Chwilio Negeseuon…">
+<!ENTITY searchMailCmd.accesskey "N">
+<!ENTITY searchMailCmd.key "f">
+<!ENTITY glodaSearchCmd.label "Chwilio Eang…">
+<!ENTITY glodaSearchCmd.accesskey "C">
+<!ENTITY searchAddressesCmd.label "Chwilio Cyfeiriadau…">
+<!ENTITY searchAddressesCmd.accesskey "y">
+
+<!-- Go Menu -->
+<!ENTITY goMenu.label "Mynd">
+<!ENTITY goMenu.accesskey "M">
+<!ENTITY nextMenu.label "Nesaf">
+<!ENTITY nextMenu.accesskey "N">
+<!ENTITY nextMsgCmd.label "Neges">
+<!ENTITY nextMsgCmd.accesskey "N">
+<!ENTITY nextMsgCmd.key "f">
+<!ENTITY nextUnreadMsgCmd.label "Neges Heb ei Darllen">
+<!ENTITY nextUnreadMsgCmd.accesskey "H">
+<!ENTITY nextUnreadMsgCmd.key "n">
+<!ENTITY nextStarredMsgCmd.label "Neges Serenog">
+<!ENTITY nextStarredMsgCmd.accesskey "S">
+<!ENTITY nextUnreadThread.label "Edafedd Heb eu Darllen">
+<!ENTITY nextUnreadThread.accesskey "D">
+<!ENTITY nextUnreadThread.key "t">
+<!ENTITY prevMenu.label "Blaenorol">
+<!ENTITY prevMenu.accesskey "B">
+<!ENTITY prevMsgCmd.label "Neges">
+<!ENTITY prevMsgCmd.accesskey "N">
+<!ENTITY prevMsgCmd.key "b">
+<!ENTITY prevUnreadMsgCmd.label "Neges Heb ei Darllen">
+<!ENTITY prevUnreadMsgCmd.accesskey "D">
+<!ENTITY prevUnreadMsgCmd.key "p">
+<!ENTITY goForwardCmd.label "Ymlaen">
+<!ENTITY goForwardCmd.accesskey "Y">
+<!ENTITY goForwardCmd.commandKey "]">
+<!ENTITY goBackCmd.label "Nôl">
+<!ENTITY goBackCmd.accesskey "N">
+<!ENTITY goBackCmd.commandKey "[">
+<!ENTITY goChatCmd.label "Sgwrsio">
+<!ENTITY goChatCmd.accesskey "g">
+<!ENTITY prevStarredMsgCmd.label "Neges Serennog">
+<!ENTITY prevStarredMsgCmd.accesskey "S">
+<!ENTITY folderMenu.label "Ffolder">
+<!ENTITY folderMenu.accesskey "o">
+<!ENTITY goRecentlyClosedTabs.label "Tabiau Wedi'u Cau'n Ddiweddar">
+<!ENTITY goRecentlyClosedTabs.accesskey "T">
+<!ENTITY startPageCmd.label "Tudalen Cychwyn E-bost">
+<!ENTITY startPageCmd.accesskey "T">
+
+<!-- Message Menu -->
+<!ENTITY msgMenu.label "Neges">
+<!ENTITY msgMenu.accesskey "N">
+<!ENTITY newMsgCmd.label "Neges Newydd">
+<!ENTITY newMsgCmd.accesskey "N">
+<!ENTITY newNewMsgCmd.label "Neges">
+<!ENTITY newNewMsgCmd.accesskey "e">
+<!ENTITY archiveMsgCmd.label "Archif">
+<!ENTITY archiveMsgCmd.accesskey "A">
+<!ENTITY archiveMsgCmd.key "a">
+<!ENTITY cancelNewsMsgCmd.label "Diddymu Neges">
+<!ENTITY cancelNewsMsgCmd.accesskey "D">
+<!ENTITY replyMsgCmd.label "Ateb">
+<!ENTITY replyMsgCmd.accesskey "A">
+<!ENTITY replyMsgCmd.key "r">
+<!ENTITY replySenderCmd.label "Ateb i'r Anfonwr yn Unig">
+<!ENTITY replySenderCmd.accesskey "t">
+<!ENTITY replyNewsgroupCmd2.label "Dilyn Grŵp Newyddion">
+<!ENTITY replyNewsgroupCmd2.accesskey "D">
+<!ENTITY replyToAllMsgCmd.label "Ateb i Bawb">
+<!ENTITY replyToAllMsgCmd.accesskey "B">
+<!ENTITY replyToAllMsgCmd.key "r">
+<!ENTITY replyToListMsgCmd.label "Ateb i'r Rhestr">
+<!ENTITY replyToListMsgCmd.accesskey "R">
+<!ENTITY replyToListMsgCmd.key "l">
+<!ENTITY forwardMsgCmd.label "Ymlaen">
+<!ENTITY forwardMsgCmd.accesskey "Y">
+<!ENTITY forwardMsgCmd.key "l">
+<!ENTITY forwardAsMenu.label "Ymlaen Fel">
+<!ENTITY forwardAsMenu.accesskey "Y">
+<!ENTITY forwardAsInline.label "Mewnlin">
+<!ENTITY forwardAsInline.accesskey "M">
+<!ENTITY forwardAsAttachmentCmd.label "Atodiad">
+<!ENTITY forwardAsAttachmentCmd.accesskey "A">
+<!ENTITY editAsNewMsgCmd.label "Golygu fel Neges Newydd">
+<!ENTITY editAsNewMsgCmd.accesskey "G">
+<!ENTITY editAsNewMsgCmd.key "g">
+<!ENTITY editDraftMsgCmd.label "Golygu Neges Ddrafft">
+<!ENTITY editDraftMsgCmd.accesskey "D">
+<!ENTITY editTemplateMsgCmd.label "Golygu Templed">
+<!ENTITY editTemplateMsgCmd.accesskey "T">
+<!ENTITY newMsgFromTemplateCmd.label "Neges Newydd o Dempled">
+<!ENTITY newMsgFromTemplateCmd.keycode "VK_RETURN"><!-- do not change "VK_RETURN" -->
+<!ENTITY createFilter.label "Creu Hidl o'r Neges…">
+<!ENTITY createFilter.accesskey "H">
+<!ENTITY moveMsgToMenu.label "Symud i">
+<!ENTITY moveMsgToMenu.accesskey "S">
+<!ENTITY moveCopyMsgRecentMenu.label "Diweddar">
+<!ENTITY moveCopyMsgRecentMenu.accesskey "D">
+<!ENTITY copyMessageLocation.label "Copïo Lleoliad Neges">
+<!ENTITY copyMessageLocation.accesskey "L">
+<!ENTITY copyMsgToMenu.label "Copïo i">
+<!ENTITY copyMsgToMenu.accesskey "C">
+<!ENTITY moveToFolderAgain.label "Symud Eto">
+<!ENTITY moveToFolderAgain.accesskey "y">
+<!ENTITY moveToFolderAgainCmd.key "m">
+<!ENTITY killThreadMenu.label "Anwybyddu'r Edefyn">
+<!ENTITY killThreadMenu.accesskey "A">
+<!ENTITY killThreadMenu.key "k">
+<!ENTITY killSubthreadMenu.label "Anwybyddu'r Is-Edefyn">
+<!ENTITY killSubthreadMenu.accesskey "I">
+<!ENTITY killSubthreadMenu.key "k">
+<!ENTITY watchThreadMenu.label "Gwylio'r Edefyn">
+<!ENTITY watchThreadMenu.accesskey "w">
+<!ENTITY watchThreadMenu.key "w">
+<!ENTITY tagMenu.label "Tag">
+<!ENTITY tagMenu.accesskey "g">
+<!ENTITY tagCmd0.key "0">
+<!ENTITY tagCmd1.key "1">
+<!ENTITY tagCmd2.key "2">
+<!ENTITY tagCmd3.key "3">
+<!ENTITY tagCmd4.key "4">
+<!ENTITY tagCmd5.key "5">
+<!ENTITY tagCmd6.key "6">
+<!ENTITY tagCmd7.key "7">
+<!ENTITY tagCmd8.key "8">
+<!ENTITY tagCmd9.key "9">
+<!ENTITY markMenu.label "Marcio">
+<!ENTITY markMenu.accesskey "M">
+<!ENTITY toggleReadCmd.key "m">
+<!ENTITY markAsReadCmd.label "Wedi ei Ddarllen">
+<!ENTITY markAsReadCmd.accesskey "W">
+<!ENTITY markAsUnreadCmd.label "Heb ei Ddarllen">
+<!ENTITY markAsUnreadCmd.accesskey "H">
+<!ENTITY markThreadAsReadCmd.label "Edefyn wedi'i Ddarllen">
+<!ENTITY markThreadAsReadCmd.accesskey "D">
+<!ENTITY markThreadAsReadCmd.key "r">
+<!ENTITY markReadByDateCmd.label "Wedi Darllen yn ôl Dyddiad…">
+<!ENTITY markReadByDateCmd.accesskey "D">
+<!ENTITY markReadByDateCmd.key "c">
+<!ENTITY markAllReadCmd.label "Popeth Wedi ei Ddarllen">
+<!ENTITY markAllReadCmd.accesskey "P">
+<!ENTITY markAllReadCmd.key "c">
+<!ENTITY markStarredCmd.label "Ychwanegu Seren">
+<!ENTITY markStarredCmd.accesskey "S">
+<!ENTITY markStarredCmd.key "S">
+<!ENTITY markAsJunkCmd.label "Fel Sbam">
+<!ENTITY markAsJunkCmd.accesskey "b">
+<!ENTITY markAsJunkCmd.key "j">
+<!ENTITY markAsNotJunkCmd.label "Fel Nid Sbam">
+<!ENTITY markAsNotJunkCmd.accesskey "N">
+<!ENTITY markAsNotJunkCmd.key "j">
+<!ENTITY recalculateJunkScoreCmd.label "Rhedeg Rheolydd E-bost Sbam">
+<!ENTITY recalculateJunkScoreCmd.accesskey "R">
+<!ENTITY openMessageWindowCmd.label "Agor Neges">
+<!ENTITY openMessageWindowCmd.accesskey "A">
+<!ENTITY openMessageWindowCmd.key "o">
+<!ENTITY openInConversationCmd.label "Agor mewn Sgwrs">
+<!ENTITY openInConversationCmd.accesskey "s">
+<!ENTITY openInConversationCmd.key "o">
+<!ENTITY openAttachmentListCmd.label "Atodiadau">
+<!ENTITY openAttachmentListCmd.accesskey "t">
+<!ENTITY openFeedMessage1.label "Wrth Agor Negeseuon Llif">
+<!ENTITY openFeedMessage1.accesskey "L">
+<!ENTITY openFeedWebPage.label "Agor fel Tudalen Gwe">
+<!ENTITY openFeedWebPage.accesskey "G">
+<!ENTITY openFeedSummary.label "Agor fel Crynodeb">
+<!ENTITY openFeedSummary.accesskey "C">
+<!ENTITY openFeedWebPageInMP.label "Toglo Tudalen We a Chrynodeb mewn Paen Neges">
+<!ENTITY openFeedWebPageInMP.accesskey "T">
+
+<!-- Windows Menu -->
+<!ENTITY windowMenu.label "Ffenestr">
+
+<!-- Tools Menu -->
+<!ENTITY tasksMenu.label "Offer">
+<!ENTITY tasksMenu.accesskey "O">
+<!ENTITY messengerCmd.label "E-bost a Grwpiau Newyddion">
+<!ENTITY messengerCmd.accesskey "E">
+<!ENTITY addressBookCmd.label "Llyfr Cyfeiriadau">
+<!ENTITY addressBookCmd.accesskey "L">
+<!ENTITY addressBookCmd.key "B">
+<!ENTITY addonNoPrefs.label "Heb ganfod gosodiadau Ychwanegion.">
+<!ENTITY activitymanager.label "Rheolwr Gweithgaredd">
+<!ENTITY activitymanager.accesskey "R">
+<!ENTITY imAccountsStatus.label "Statws Sgwrsio">
+<!ENTITY imAccountsStatus.accesskey "t">
+<!ENTITY imStatus.available          "Ar Gael">
+<!ENTITY imStatus.unavailable        "Ddim ar Gael">
+<!ENTITY imStatus.offline            "All-lein">
+<!ENTITY imStatus.showAccounts       "Dangos Cyfrifon…">
+<!ENTITY joinChatCmd.label "Ymuno â Sgwrs…">
+<!ENTITY joinChatCmd.accesskey "Y">
+<!ENTITY savedFiles.label "Ffeiliau wedi'u Cadw">
+<!ENTITY savedFiles.accesskey "F">
+<!ENTITY savedFiles.key "j">
+<!ENTITY filtersCmd2.label "Hidlau Negeseuon">
+<!ENTITY filtersCmd2.accesskey "H">
+<!ENTITY filtersApply.label "Rhedeg Hidlau ar Ffolder">
+<!ENTITY filtersApply.accesskey "R">
+<!ENTITY filtersApplyToSelection.label "Rhedeg Hidlau ar Negeseuon Penodol">
+<!ENTITY filtersApplyToSelection.accesskey "P">
+<!ENTITY filtersApplyToMessage.label "Rhedeg Hidlau ar Neges">
+<!ENTITY filtersApplyToMessage.accesskey "N">
+<!ENTITY runJunkControls.label "Rhedeg Rheolydd Sbam ar Ffolder">
+<!ENTITY runJunkControls.accesskey "R">
+<!ENTITY deleteJunk.label "Dileu E-bost wedi'i Nodi fel Sbam yn y Ffolder">
+<!ENTITY deleteJunk.accesskey "D">
+<!ENTITY importCmd.label "Mewnforio…">
+<!ENTITY importCmd.accesskey "M">
+<!ENTITY exportCmd.label "Allforio…">
+<!ENTITY exportCmd.accesskey "A">
+<!ENTITY clearRecentHistory.label "Clirio Hanes Diweddar…">
+<!ENTITY clearRecentHistory.accesskey "H">
+<!ENTITY accountManagerCmd2.label "Gosodiadau'r Cyfrif">
+<!ENTITY accountManagerCmd2.accesskey "G">
+<!-- LOCALIZATION NOTE (accountManagerCmdUnix.accesskey):
+     Belongs to accountManagerCmd.label, which is placed under the Edit menu
+     on Unix systems
+  -->
+<!ENTITY accountManagerCmdUnix2.accesskey "A">
+
+<!-- Developer Tools Submenu -->
+<!ENTITY devtoolsMenu.label "Offer Datblygwyr">
+<!ENTITY devtoolsMenu.accesskey "D">
+<!ENTITY devToolboxCmd.label "Blwch Offer Datblygwyr">
+<!ENTITY devToolboxCmd.accesskey "B">
+<!ENTITY devToolboxCmd.commandkey "i">
+<!ENTITY debugAddonsCmd.label "Ychwanegion Dadfygio">
+<!ENTITY debugAddonsCmd.accesskey "Y">
+<!ENTITY errorConsoleCmd.label "Consol Gwall">
+<!ENTITY errorConsoleCmd.accesskey "C">
+<!ENTITY errorConsoleCmd.commandkey "j">
+
+<!-- Mail Toolbar -->
+<!ENTITY getMsgButton1.label "Estyn Negeseuon">
+<!ENTITY newMsgButton.label "Ysgrifennu">
+<!ENTITY replyButton.label "Ateb">
+<!ENTITY replyAllButton.label "Ateb Pawb">
+<!ENTITY replyListButton.label "Ateb i'r Rhestr">
+<!ENTITY forwardButton.label "Ymlaen">
+<!ENTITY fileButton.label "Ffeil">
+<!ENTITY archiveButton.label "Archifo">
+<!ENTITY openConversationButton.label "Sgwrs">
+<!ENTITY nextButton.label "Nesaf">
+<!ENTITY nextButtonToolbarItem.label "Nesaf Heb ei Ddarllen">
+<!ENTITY nextMsgButton.label "Nesaf">
+<!ENTITY previousButton.label "Blaenorol">
+<!ENTITY previousButtonToolbarItem.label "Blaenorol Heb ei Ddarllen">
+<!ENTITY previousMsgButton.label "Blaenorol">
+<!ENTITY backButton1.label "Nôl">
+<!ENTITY goForwardButton1.label "Ymlaen">
+<!ENTITY deleteItem.title "Dileu">
+<!ENTITY markButton.label "Marcio">
+<!ENTITY printButton.label "Argraffu">
+<!ENTITY stopButton.label "Atal">
+<!ENTITY throbberItem.title "Dangosydd Gweithgaredd">
+<!ENTITY junkItem.title "Sbam">
+<!ENTITY addressBookButton.label "Llyfr Cyfeiriadau">
+<!ENTITY chatButton.label "Sgwrsio">
+<!ENTITY glodaSearch.title "Chwilio Eang">
+<!ENTITY searchItem.title "Chwilio Cyflym">
+<!ENTITY mailViewsToolbarItem.title "Golwg E-bost">
+<!ENTITY folderLocationToolbarItem.title "Lleoliad Ffolder">
+<!ENTITY tagButton.label "Tag">
+<!ENTITY compactButton.label "Cywasgu">
+<!ENTITY appmenuButton.label "AppMenu">
+
+<!-- Mail Toolbar Tooltips-->
+<!ENTITY advancedButton.tooltip "Chwilio neges uwch">
+<!ENTITY getMsgButton.tooltip "Estyn negeseuon newydd">
+<!ENTITY getAllNewMsgCmd.label "Estyn Pob Neges Newydd">
+<!ENTITY getAllNewMsgCmd.accesskey "E">
+<!ENTITY newMsgButton.tooltip "Creu neges newydd">
+<!ENTITY replyButton.tooltip "Ateb y neges">
+<!ENTITY replyAllButton.tooltip "Ateb yr anfonwr a phob derbyniwr">
+<!ENTITY replyListButton.tooltip "Ateb i'r rhestr e-bost">
+<!ENTITY forwardButton.tooltip "Anfon y neges ymlaen">
+<!ENTITY forwardAsInline.tooltip "Anfon neges dewiswyd ymlaen fel testun mewnlin">
+<!ENTITY forwardAsAttachment.tooltip "Anfon neges dewiswyd ymlaen fel atodiad">
+<!ENTITY fileButton.tooltip "Ffeilio'r neges">
+<!ENTITY archiveButton.tooltip "Archifo'r negeseuon">
+<!ENTITY openMsgConversationButton.tooltip "Dangos sgwrs neges sydd wedi ei dewis">
+<!ENTITY nextButton.tooltip "Symud i'r neges nesaf heb ei darllen">
+<!ENTITY nextMsgButton.tooltip "Symud i'r neges nesaf">
+<!ENTITY previousButton.tooltip "Symud i'r neges heb ei darllen diwethaf">
+<!ENTITY previousMsgButton.tooltip "Symud i'r neges flaenorol">
+<!ENTITY goForwardButton.tooltip "Mynd ymlaen un neges">
+<!ENTITY goBackButton.tooltip "Mynd nôl un neges">
+<!ENTITY markButton.tooltip "Marcio negeseuon">
+<!ENTITY printButton.tooltip "Argraffu'r neges">
+<!ENTITY stopButton.tooltip "Atal y trosglwyddiad cyfredol">
+<!ENTITY addressBookButton.tooltip "Mynd i'r llyfr cyfeiriadau">
+<!ENTITY chatButton.tooltip "Dangos y tab Sgwrsio">
+<!ENTITY tagButton.tooltip "Tagio negeseuon">
+<!ENTITY compactButton.tooltip "Tynnu negeseuon wedi'u dileu o'r ffolder">
+<!ENTITY appmenuButton1.tooltip "Dangos Dewislen &brandShortName;">
+
+<!-- Toolbar Button Popup -->
+<!ENTITY buttonMenuForwardAsInline.label "Anfon Ymlaen fel Mewnlin">
+<!ENTITY buttonMenuForwardAsAttachment.label "Anfon Ymlaen fel Atodiad">
+
+<!-- Remote Content Button Popup -->
+<!ENTITY remoteContentOptionsAllowForMsg.label "Dangos cynnwys pell o fewn y neges hon">
+<!ENTITY remoteContentOptionsAllowForMsg.accesskey "D">
+<!ENTITY editRemoteContentSettings.label "Golygu dewisiadau cynnwys pell…">
+<!ENTITY editRemoteContentSettings.accesskey "G">
+<!ENTITY editRemoteContentSettingsUnix.label "Golygu dewisiadau cynnwys pell…">
+<!ENTITY editRemoteContentSettingsUnix.accesskey "d">
+
+<!-- Phishing Button Popup -->
+<!ENTITY phishingOptionIgnore.label "Anwybyddu rhybudd am y neges hon">
+<!ENTITY phishingOptionIgnore.accesskey "A">
+<!ENTITY phishingOptionSettings.label "Golygu dewisiadau canfod twyll…">
+<!ENTITY phishingOptionSettings.accesskey "o">
+<!ENTITY phishingOptionSettingsUnix.label "Golygu dewisiadau canfod twyll…">
+<!ENTITY phishingOptionSettingsUnix.accesskey "o">
+
+<!-- AppMenu Popup -->
+<!ENTITY appmenuNewMsgCmd.label "Neges Newydd">
+<!ENTITY appmenuNewContactCmd.label "Cysylltiad Llyfr Cyfeiriadau…">
+<!ENTITY appmenuEditMenu.label "Golygu">
+<!ENTITY appmenuToolbarLayout.label "Cynllun Bar Offer…">
+<!ENTITY appmenuSelectThread.label "Dewis Edefyn">
+<!ENTITY appmenuSelectFlagged.label "Estyn Negeseuon Serennog">
+
+<!-- Tags Menu Popup -->
+<!ENTITY addNewTag.label "Tag Newydd…">
+<!ENTITY addNewTag.accesskey "T">
+<!ENTITY manageTags.label "Rheoli Tagiau…">
+<!ENTITY manageTags.accesskey "T">
+
+<!-- Folder Pane -->
+<!ENTITY folderNameColumn.label "Enw">
+<!ENTITY folderUnreadColumn.label "Heb ei Ddarllen">
+<!ENTITY folderTotalColumn.label "Cyfanswm">
+<!ENTITY folderSizeColumn.label "Maint">
+
+<!-- Folder Pane Context Menu -->
+<!ENTITY folderContextGetMessages.label "Estyn Negeseuon">
+<!ENTITY folderContextGetMessages.accesskey "s">
+<!ENTITY folderContextMarkAllFoldersRead.label "Marcio Pob Ffolder Wedi'u Darllen">
+<!ENTITY folderContextPauseAllUpdates.label "Oedi Pob Diweddariad">
+<!ENTITY folderContextPauseUpdates.label "Oedi Diweddariadau">
+<!ENTITY folderContextPauseUpdates.accesskey "D">
+<!ENTITY folderContextOpenInNewWindow.label "Agor mewn Ffenestr Newydd">
+<!ENTITY folderContextOpenInNewWindow.accesskey "N">
+<!ENTITY folderContextOpenNewTab.label "Agor mewn Tab Newydd">
+<!ENTITY folderContextOpenNewTab.accesskey "T">
+<!ENTITY folderContextNew.label "Is ffolder Newydd…">
+<!ENTITY folderContextNew.accesskey "I">
+<!ENTITY folderContextRename.label "Ailenwi">
+<!ENTITY folderContextRename.accesskey "A">
+<!ENTITY folderContextRemove.label "Dileu">
+<!ENTITY folderContextRemove.accesskey "D">
+<!ENTITY folderContextCompact.label "Cywasgu">
+<!ENTITY folderContextCompact.accesskey "C">
+<!ENTITY folderContextEmptyTrash.label "Gwagio'r Sbwriel">
+<!ENTITY folderContextEmptyTrash.accesskey "G">
+<!ENTITY folderContextEmptyJunk.label "Gwagio'r Sbam">
+<!ENTITY folderContextEmptyJunk.accesskey "S">
+<!ENTITY folderContextSendUnsentMessages.label "Anfon Negeseuon heb eu Hanfon">
+<!ENTITY folderContextSendUnsentMessages.accesskey "A">
+<!ENTITY folderContextUnsubscribe.label "Dad-danysgrifio">
+<!ENTITY folderContextUnsubscribe.accesskey "D">
+<!ENTITY folderContextMarkNewsgroupRead.label "Marcio Grŵp Newyddion Wedi'i Ddarllen">
+<!ENTITY folderContextMarkNewsgroupRead.accesskey "G">
+<!ENTITY folderContextMarkMailFolderRead.label "Marcio Ffolder Wedi'i Ddarllen">
+<!ENTITY folderContextMarkMailFolderRead.accesskey "W">
+<!ENTITY folderContextSubscribe.label "Tanysgrifio…">
+<!ENTITY folderContextSubscribe.accesskey "T">
+<!ENTITY folderContextSearchForMessages.label "Chwilio Negeseuon…">
+<!ENTITY folderContextSearchForMessages.accesskey "C">
+<!ENTITY folderContextProperties2.label "Priodweddau">
+<!ENTITY folderContextProperties2.accesskey "P">
+<!ENTITY folderContextFavoriteFolder.label "Hoff Ffolder">
+<!ENTITY folderContextFavoriteFolder.accesskey "H">
+<!ENTITY folderContextSettings2.label "Gosodiadau">
+<!ENTITY folderContextSettings2.accesskey "o">
+
+<!-- Search Bar -->
+<!ENTITY SearchNameOrEmail.label "Mae'r Enw neu E-bost yn cynnwys:">
+<!ENTITY SearchNameOrEmail.accesskey "E">
+
+<!-- Gloda Search Bar -->
+<!ENTITY glodaSearchBar.placeholder "Chwilio negeseuon…">
+
+<!-- Quick Search Menu Bar -->
+<!ENTITY searchSubjectMenu.label "Pwnc">
+<!ENTITY searchFromMenu.label "Oddi wrth">
+<!ENTITY searchSubjectOrFromMenu.label "Pwnc neu Oddi wrth">
+<!ENTITY searchRecipient.label "At neu Cc">
+<!ENTITY searchSubjectOrRecipientMenu.label "Pwnc, At neu Cc">
+<!ENTITY searchMessageBody.label "Neges Gyfan">
+<!ENTITY saveAsVirtualFolderMenu.label "Cadw'r Chwilio fel Ffolder…">
+
+<!-- Thread Pane -->
+<!ENTITY selectColumn.label "Dewis Negeseuon">
+<!ENTITY threadColumn.label "Edefyn">
+<!ENTITY fromColumn.label "Oddi wrth">
+<!ENTITY recipientColumn.label "Derbynnydd">
+<!ENTITY correspondentColumn.label "Cyfathrebwyr">
+<!ENTITY subjectColumn.label "Pwnc">
+<!ENTITY dateColumn.label "Dyddiad">
+<!ENTITY priorityColumn.label "Blaenoriaeth">
+<!ENTITY tagsColumn.label "Tag">
+<!ENTITY accountColumn.label "Cyfrif">
+<!ENTITY statusColumn.label "Statws">
+<!ENTITY sizeColumn.label "Maint">
+<!ENTITY junkStatusColumn.label "Statws Sbam">
+<!ENTITY unreadColumn.label "Heb ei Ddarllen">
+<!ENTITY totalColumn.label "Cyfanswm">
+<!ENTITY readColumn.label "Darllenwyd">
+<!ENTITY receivedColumn.label "Derbyniwyd">
+<!ENTITY starredColumn.label "Serennog">
+<!ENTITY locationColumn.label "Lleoliad">
+<!ENTITY idColumn.label "Trefn Derbyn">
+<!ENTITY attachmentColumn.label "Atodiadau">
+<!ENTITY deleteColumn.label "Dileu">
+
+<!-- Thread Pane Tooltips -->
+<!ENTITY columnChooser2.tooltip "Dewis colofnau i'w dangos">
+<!ENTITY selectColumn.tooltip "Toglo dewis pob neges">
+<!ENTITY threadColumn2.tooltip "Dangos edafedd negeseuon">
+<!ENTITY fromColumn2.tooltip "Trefnu yn ôl anfonwr">
+<!ENTITY recipientColumn2.tooltip "Trefnu yn ôl derbyniwr">
+<!ENTITY correspondentColumn2.tooltip "Trefnu yn ôl cyfathrebwyr">
+<!ENTITY subjectColumn2.tooltip "Trefnu yn ôl pwnc">
+<!ENTITY dateColumn2.tooltip "Trefnu yn ôl dyddiad">
+<!ENTITY priorityColumn2.tooltip "Trefnu yn ôl blaenoriaeth">
+<!ENTITY tagsColumn2.tooltip "Trefnu yn ôl tagiau">
+<!ENTITY accountColumn2.tooltip "Trefnu yn ôl cyfrif">
+<!ENTITY statusColumn2.tooltip "Trefnu yn ôl statws">
+<!ENTITY sizeColumn2.tooltip "Trefnu yn ôl maint">
+<!ENTITY junkStatusColumn2.tooltip "Trefnu yn ôl statws sbam">
+<!ENTITY unreadColumn2.tooltip "Nifer y negeseuon heb eu darllen yn yr edafedd">
+<!ENTITY totalColumn2.tooltip "Cyfanswm y nifer o negeseuon yn yr edafedd">
+<!ENTITY readColumn2.tooltip "Trefnu yn ôl darllenwyd">
+<!ENTITY receivedColumn2.tooltip "Trefnu yn ôl dyddiad derbyniwyd">
+<!ENTITY starredColumn2.tooltip "Trefnu yn ôl sêr">
+<!ENTITY locationColumn2.tooltip "Trefnu yn ôl lleoliad">
+<!ENTITY idColumn2.tooltip "Trefnu yn ôl y drefn derbyniwyd">
+<!ENTITY attachmentColumn2.tooltip "Trefnu yn ôl atodiad">
+<!ENTITY deleteColumn.tooltip "Dileu neges">
+
+<!-- Thread Pane Context Menu -->
+<!ENTITY contextNewMsgFromTemplate.label "Neges Newydd o Dempled">
+<!ENTITY contextOpenNewWindow.label "Agor Neges mewn Ffenestr Newydd">
+<!ENTITY contextOpenNewWindow.accesskey "F">
+<!-- The contextOpenNewTab.accesskey ("T") potentially conflicts with
+     cutCmd.accessKey which is defined in textcontext.dtd from toolkit. Right
+     now, both menu items can't be visible at the same time, but should someone
+     enable copy/paste of message, this key would probably need to be changed. -->
+<!ENTITY contextOpenNewTab.label "Agor Neges mewn Tab Newydd">
+<!ENTITY contextOpenNewTab.accesskey "T">
+<!ENTITY contextOpenConversation.label "Agor Neges mewn Sgwrs">
+<!ENTITY contextOpenConversation.accesskey "s">
+<!ENTITY contextOpenContainingFolder.label "Agor Neges yn y Ffolder Cynnwys">
+<!ENTITY contextOpenContainingFolder.accesskey "A">
+<!ENTITY contextEditMsgAsNew.label "Golygu fel Neges Newydd">
+<!ENTITY contextEditMsgAsNew.accesskey "N">
+<!ENTITY contextEditDraftMsg.label "Golygu Neges Ddrafft">
+<!ENTITY contextEditTemplate.label "Golygu Templed">
+<!ENTITY contextEditTemplate.accesskey "T">
+<!ENTITY contextArchive.label "Archifo">
+<!ENTITY contextArchive.accesskey "A">
+<!ENTITY contextReplySender.label "Ateb i'r Anfonwr yn Unig">
+<!ENTITY contextReplySender.accesskey "n">
+<!ENTITY contextReplyNewsgroup2.label "Dilyn Grŵp Newyddion">
+<!ENTITY contextReplyNewsgroup2.accesskey "D">
+<!ENTITY contextReplyAll.label "Ateb i Bawb">
+<!ENTITY contextReplyAll.accesskey "B">
+<!ENTITY contextReplyList.label "Ateb i'r Rhestr">
+<!ENTITY contextReplyList.accesskey "R">
+<!ENTITY contextForward.label "Ymlaen">
+<!ENTITY contextForward.accesskey "Y">
+<!ENTITY contextForwardAsMenu.label "Ymlaen Fel">
+<!ENTITY contextForwardAsMenu.accesskey "Y">
+<!ENTITY contextForwardAsInline.label "Mewnlin">
+<!ENTITY contextForwardAsInline.accesskey "M">
+<!ENTITY contextForwardAsAttachmentItem.label "Atodiad">
+<!ENTITY contextForwardAsAttachmentItem.accesskey "A">
+<!ENTITY contextMultiForwardAsAttachment.label "Ymlaen fel Atodiadau">
+<!ENTITY contextMultiForwardAsAttachment.accesskey "A">
+<!ENTITY contextMoveMsgMenu.label "Symud i">
+<!ENTITY contextMoveMsgMenu.accesskey "S">
+<!ENTITY contextMoveCopyMsgRecentMenu.label "Diweddar">
+<!ENTITY contextMoveCopyMsgRecentMenu.accesskey "D">
+<!ENTITY contextMoveCopyMsgFavoritesMenu.label "Ffefrynnau">
+<!ENTITY contextMoveCopyMsgFavoritesMenu.accesskey "F">
+<!ENTITY contextCopyMsgMenu.label "Copïo i">
+<!ENTITY contextCopyMsgMenu.accesskey "C">
+<!ENTITY contextKillThreadMenu.label "Anwybyddu'r Edefyn">
+<!ENTITY contextKillSubthreadMenu.accesskey "I">
+<!ENTITY contextKillThreadMenu.accesskey "A">
+<!ENTITY contextKillSubthreadMenu.label "Anwybyddu'r Is-Edefyn">
+<!ENTITY contextWatchThreadMenu.label "Gwylio'r Edefyn">
+<!-- LOCALIZATION NOTE (contextWatchThreadMenu.accesskey):
+     In the en-US locale we ran out of access keys, so there is an empty access key for
+     Watch Thread. Localizers can pick a suitable key
+  -->
+<!ENTITY contextWatchThreadMenu.accesskey "">
+<!ENTITY contextSaveAs.label "Cadw Fel…">
+<!ENTITY contextSaveAs.accesskey "a">
+<!ENTITY contextPrint.label "Argraffu…">
+<!ENTITY contextPrint.accesskey "A">
+<!ENTITY contextPrintPreview.label "Rhagolwg Argraffu">
+<!ENTITY contextPrintPreview.accesskey "R">
+
+<!-- LOCALIZATION NOTE (columnPicker.applyTo.label):
+     This option in the thread pane column picker pops up a sub-menu containing
+     the "columnPicker.applyToFolder.label" and
+     "columnPicker.applyToFolderAndChildren.label" options. This item indicates
+     a desire to apply the currently displayed set of columns to some other
+     folder(s). The sub-menu items indicate whether we want to apply it to just
+     a folder or also its children.
+  -->
+<!ENTITY columnPicker.applyTo.label "Gosod y colofnau yn y…">
+<!-- LOCALIZATION NOTE (columnPicker.applyToFolder.label):
+     This option in the thread pane column picker is found on a sub-menu beneath
+     the "columnPicker.applyTo.label" alongside
+     "columnPicker.applyToFolderAndChildren.label". It indicates a desire to
+     apply the currently display thread pane column settings to a single folder
+     that the user selects using the same widget as the move to/copy to
+     mechanism (via a series of popups).
+  -->
+<!ENTITY columnPicker.applyToFolder.label "Ffolder…">
+<!-- LOCALIZATION NOTE (columnPicker.applyToFolderAndChildren.label):
+     This option in the thread pane column picker is found on a sub-menu beneath
+     the "columnPicker.applyTo.label" alongside
+     "columnPicker.applyToFolder.label". It indicates a desire to
+     apply the currently display thread pane column settings to a folder and all
+     of its descendents. The user selects the folder using the same widget as the
+     move to/copy to mechanism (via a series of popups).
+  -->
+<!ENTITY columnPicker.applyToFolderAndChildren.label "Ffolder a'i blant…">
+<!-- LOCALIZATION NOTE (columnPicker.thisFolder.label):
+     This is used in the folder selection widget for the
+     "columnPicker.applyToFolder.label" and
+     "columnPicker.applyToFolderAndChildren.label" menu options. Whenever
+     a folder has children, it results in a menu popup; the first menu item
+     in that popup is given this label to indicate that that folder should be
+     selected. For example, if folder "A" has two children, "B" and "C", then
+     when the user hovers over "A", a new popup menu will be displayed whose
+     items are "This folder", "B", and "C". This is the equivalent of the
+     "File here" option for the move to/copy to widget.
+  -->
+<!ENTITY columnPicker.thisFolder.label "Y ffolder hwn">
+
+<!-- Media (video/audio) controls -->
+<!ENTITY contextPlay.label "Chwarae">
+<!ENTITY contextPlay.accesskey "h">
+<!ENTITY contextPause.label "Oedi">
+<!ENTITY contextPause.accesskey "O">
+<!ENTITY contextMute.label "Tewi">
+<!ENTITY contextMute.accesskey "T">
+<!ENTITY contextUnmute.label "Dad-dewi">
+<!ENTITY contextUnmute.accesskey "D">
+
+<!-- Quick Search Bar -->
+<!-- LOCALIZATION NOTE (quickSearchCmd.key):
+     This is actually the key used for the global message search box; we have
+     not changed
+  -->
+<!ENTITY quickSearchCmd.key "k">
+<!-- LOCALIZATION NOTE (search.label.base1):
+     This is the base of the empty text for the global search box. We replace
+     #1 with the contents of the appropriate search.keyLabel.* value for the
+     platform.
+     The goal is to convey to the user that typing in the box will allow them
+     to search for messages globally and that there is a hotkey they can press
+     to get to the box faster. If the global indexer is disabled, the search
+     box will be collapsed and the user will never see this message.
+  -->
+<!ENTITY search.label.base1 "Chwilio #1">
+<!-- LOCALIZATION NOTE (search.keyLabel.nonmac):
+     The description of the key-binding to get into the global search box on
+     windows and linux (which use the control key). We use the key defined in
+     the quickSearchCmd.key entity defined above, the letter should match it.
+  -->
+<!ENTITY search.keyLabel.nonmac "&lt;Ctrl+K&gt;">
+<!-- LOCALIZATION NOTE (search.keyLabel.mac):
+     The description of the key-binding to get into the global search box on mac
+     systems. We use the key defined in the quickSearchCmd.key entity defined
+     above, the letter should match it.
+  -->
+<!ENTITY search.keyLabel.mac "&lt;&#x2318;K&gt;">
+
+<!-- Message Header Context Menu -->
+<!ENTITY AddToAddressBook.label "Ychwanegu i'r Llyfr Cyfeiriadau…">
+<!ENTITY AddToAddressBook.accesskey "L">
+<!ENTITY AddDirectlyToAddressBook.label "Ychwanegu i'r Llyfr Cyfeiriadau">
+<!ENTITY AddDirectlyToAddressBook.accesskey "C">
+<!ENTITY EditContact1.label "Golygu Cysylltiad">
+<!ENTITY EditContact1.accesskey "G">
+<!ENTITY ViewContact.label "Gweld Cysylltiad">
+<!ENTITY ViewContact.accesskey "w">
+<!ENTITY SubscribeToNewsgroup.label "Tanysgrifio i Grŵp Newyddion">
+<!ENTITY SubscribeToNewsgroup.accesskey "N">
+<!ENTITY SendMessageTo.label "Ysgrifennu Neges At">
+<!ENTITY SendMessageTo.accesskey "Y">
+<!ENTITY CopyEmailAddress.label "Copïo Cyfeiriad E-bost">
+<!ENTITY CopyEmailAddress.accesskey "C">
+<!ENTITY CopyNameAndEmailAddress.label "Copïo Enw a Chyfeiriad E-bost">
+<!ENTITY CopyNameAndEmailAddress.accesskey "E">
+<!ENTITY CopyNewsgroupName.label "Copïo Enw Grŵp Newyddion">
+<!ENTITY CopyNewsgroupName.accesskey "N">
+<!ENTITY CopyNewsgroupURL.label "Copïo URL Grŵp Newyddion">
+<!ENTITY CopyNewsgroupURL.accesskey "U">
+<!ENTITY CreateFilterFrom.label "Creu Hidl o…">
+<!ENTITY CreateFilterFrom.accesskey "H">
+<!ENTITY reportPhishingURL.label "Adrodd ar Dwyll E-bost">
+<!ENTITY reportPhishingURL.accesskey "A">
+
+<!-- Spell checker context menu items -->
+<!ENTITY spellAddDictionaries.label "Ychwanegu Geiriaduron…">
+<!ENTITY spellAddDictionaries.accesskey "Y">
+
+<!-- Content Pane Context Menu -->
+<!ENTITY saveLinkAsCmd.label "Cadw Dolen Fel…">
+<!ENTITY saveLinkAsCmd.accesskey "D">
+<!ENTITY saveImageAsCmd.label "Cadw Delwedd Fel…">
+<!ENTITY saveImageAsCmd.accesskey "D">
+<!ENTITY copyLinkCmd.label "Copïo Lleoliad Dolen">
+<!ENTITY copyLinkCmd.accesskey "C">
+<!ENTITY copyImageAllCmd.label "Copïo Delwedd">
+<!ENTITY copyImageAllCmd.accesskey "p">
+<!ENTITY copyEmailCmd.label "Copïo Cyfeiriad E-bost">
+<!ENTITY copyEmailCmd.accesskey "E">
+<!ENTITY stopCmd.label "Atal">
+<!ENTITY stopCmd.accesskey "A">
+<!ENTITY reloadCmd.label "Ail-lwytho">
+<!ENTITY reloadCmd.accesskey "A">
+<!ENTITY openInBrowser.label "Agor yn y Porwr">
+<!ENTITY openInBrowser.accesskey "A">
+<!ENTITY openLinkInBrowser.label "Agor Dolen yn y Porwr">
+<!ENTITY openLinkInBrowser.accesskey "D">
+
+<!-- Statusbar -->
+<!ENTITY statusText.label "Gorffen">
+
+<!-- Mac OS X Window Menu -->
+<!ENTITY minimizeWindow.label "Lleihau">
+<!ENTITY minimizeWindow.key "m">
+<!ENTITY bringAllToFront.label "Dwyn y Cyfan i'r Blaen">
+<!ENTITY zoomWindow.label "Chwyddo">
+
+<!-- Mac OS X Application Menu (Cocoa widgets) -->
+<!ENTITY preferencesCmdMac2.label       "Dewisiadau">
+<!ENTITY preferencesCmdMac.commandkey   ",">
+<!ENTITY preferencesCmdMac.modifiers    "accel">
+<!ENTITY servicesMenuMac.label          "Gwasanaethau">
+<!ENTITY hideThisAppCmdMac.label        "Cuddio &brandShortName;">
+<!ENTITY hideThisAppCmdMac.commandkey   "H">
+<!ENTITY hideThisAppCmdMac.modifiers    "accel">
+<!ENTITY hideOtherAppsCmdMac.label      "Cuddio Eraill">
+<!ENTITY hideOtherAppsCmdMac.commandkey "E">
+<!ENTITY hideOtherAppsCmdMac.modifiers  "accel,alt">
+<!ENTITY showAllAppsCmdMac.label        "Dangos Popeth">
+
+<!-- Mac OS X Dock Icon pop-up menu -->
+<!ENTITY dockOptions.label              "Dewisiadau Eicon Ap…">
+<!ENTITY writeNewMessageDock.label      "Ysgrifennu Neges Newydd">
+<!ENTITY openAddressBookDock.label      "Agor y Llyfr Cyfeiriadau">
+
+<!-- Content tab Navigation buttons -->
+<!ENTITY browseBackButton.tooltip    "Nôl un tudalen">
+<!ENTITY browseForwardButton.tooltip "Mynd ymlaen un tudalen">
diff --git a/l10n-cy/mail/chrome/messenger/messenger.properties b/l10n-cy/mail/chrome/messenger/messenger.properties
new file mode 100644
index 0000000000..150865339d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messenger.properties
@@ -0,0 +1,762 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The following are used by the messenger application
+#
+
+# LOCALIZATION NOTE(statusMessage):
+# Do not translate the words %1$S and %2$S below. Place the word %1$S where the
+# account name should appear and %2$S where the status message should appear.
+# EXAMPLE: Jim's Account: Downloading messages...
+statusMessage=%1$S: %2$S
+
+removeAccount=Dileu Cyfrif…
+newFolderMenuItem=Ffolder…
+newSubfolderMenuItem=Is-ffolder…
+newFolder=Ffolder Newydd…
+newSubfolder=Is ffolder Newydd…
+markFolderRead=Marcio Ffolder wedi'i Darllen;Marcio Ffolderi wedi'u Darllen
+markNewsgroupRead=Marcio Grŵp Newyddion wedi'i Darllen; Marcio Grwpiau Newyddion wedi'u Darllen
+folderProperties=Priodweddau Ffolderi
+newTag=Tag Newydd…
+# LOCALIZATION NOTE (getNextNewsMessages): Semi-colon list of plural forms.
+# #1 is the number of news messages to get.
+getNextNewsMessages=Estyn y #1 Neges Newyddion Nesaf;Estyn y #1 Neges Newyddion Nesaf
+advanceNextPrompt=Ymlaen i'r neges nesaf heb ei darllen yn %S?
+titleNewsPreHost=ar
+replyToSender=Ateb i'r Anfonwr
+reply=Ateb
+EMLFiles=Ffeiliau E-bost
+OpenEMLFiles=Agor Neges
+# LOCALIZATION NOTE(defaultSaveMessageAsFileName): Do not translate ".eml"
+# in the line below. Also, the complete file name should be 8.3.
+defaultSaveMessageAsFileName=message.eml
+# LOCALIZATION NOTE(longMsgSubjectTruncator): A suffix string appended to the filename
+# (created from message subject) if it needed to be truncated due to length.
+longMsgSubjectTruncator=...
+SaveMailAs=Cadw Neges Fel
+SaveAttachment=Cadw Atodiad
+SaveAllAttachments=Cadw Pob atodiad
+DetachAttachment=Datod Atodiad
+DetachAllAttachments=Datod Pob Atodiad
+ChooseFolder=Dewis Ffolder
+MessageLoaded=Neges wedi'i llwytho…
+PreviewTitle=%S - %S
+saveAttachmentFailed=Methu cadw'r atodiad. Gwiriwch enw eich ffeil a cheisiwch eto yn ddiweddarach.
+saveMessageFailed=Methu cadw'r neges. Gwirio enw'r ffeil a cheisio eto yn ddiweddarach.
+fileExists=Mae %S yn bodoli yn barod. Hoffech chi newid y ffeil?
+# LOCALIZATION NOTE(failedToReadFile): %1$S is replaced by the file name, %2$S is replaced by the reason the file load failed.
+failedToReadFile=Methu darllen ffeil : %1$S rheswm: %2$S
+
+downloadingNewsgroups=Llwytho Grwpiau Newyddion ar gyfer Defnydd All-lein
+downloadingMail=Llwytho E-bost i lawr ar gyfer Defnydd All-lein
+sendingUnsent=Anfon Negeseuon sydd Heb eu Hanfon
+
+folderExists=Mae ffolder gyda'r enw hwnnw'n bodoli eisoes. Rhowch enw arall arno.
+# LOCALIZATION NOTE(confirmDuplicateFolderRename): %1$S is name of folder being moved, %2$S is parent folder name, %3$S is proposed new folder name
+confirmDuplicateFolderRename=Mae is-ffolder gyda'r enw '%1$S' yn bodoli yn ffolder '%2$S'. Hoffech chi symud y ffolder hwn gan ddefnyddio'r enw newydd '%3$S'?
+folderCreationFailed=Methu creu'r ffolder oherwydd bod y ffolder dewiswyd yn cynnwys nod anhysbys. Rhowch enw arall a cheisiwch eto.
+
+compactingFolder=Cywasgu ffolder %S…
+# LOCALIZATION NOTE(compactingDone): %1$S is the compaction gain.
+compactingDone=Wedi cwblhau cywasgu (tua %1$S wedi ei ryddhau).
+
+confirmFolderDeletionForFilter=Bydd dileu ffolder '%S' yn analluogi'r hidl(au) cysylltiedig. Ydych chi'n siŵr eich bod chi eisiau dileu'r ffolder?
+alertFilterChanged=Bydd yr hidlau sy'n gysylltiedig â'r ffolder yn cael ei ddiweddaru.
+filterDisabled=Nid oedd modd dod o hyn i ffolder '%S', felly bydd ffolder(i) sy'n gysylltiedig a'r ffolder yn cael eu hanalluogi. Gwiriwch fod y ffolder yn bodoli a bod yr hidlau yn cyfeirio at ffolder cyrchfan gwirioneddol.
+filterFolderDeniedLocked=Nid oedd modd hidlo'r negeseuon i ffolder '%S' gan fod gweithred arall ar waith.
+parsingFolderFailed=Methu agor ffolder %S gan ei fod yn cael ei ddefnyddio gan weithred arall. Arhoswch i'r weithred ddod i ben ac yna dewis y ffolder eto.
+deletingMsgsFailed=Methu dileu negeseuon yn ffolder %S gan ei fod yn cael ei ddefnyddio gan weithred arall. Arhoswch i'r weithred ddod i ben ac yna ceisio eto.
+alertFilterCheckbox=Peidiwch â rhybuddio fi eto.
+compactFolderDeniedLock=Nid oes modd cywasgu ffolder '%S' oherwydd bod gweithred arall ar waith. Ceisiwch eto yn ddiweddarach.
+compactFolderWriteFailed=Nid oedd modd cywasgu ffolder '%S' oherwydd methodd ysgrifennu i ffolder. Gwiriwch fod gennych ddigon o le ar ddisg, a bod gennych hawl ysgrifennu i'r system ffeiliau, ac yna ceisiwch eto.
+compactFolderInsufficientSpace=Nid oes modd cywasgu rhai ffolderi (e.e. '%S') gan nad oes digon o le ar ddisg. Dilëwch rhai ffeiliau a cheisiwch eto.
+filterFolderHdrAddFailed=Nid oedd modd hidlo ffolder '%S' oherwydd methodd ychwanegu neges ato. Gwiriwch fod fod y ffolder yn ymddangos yn iawn neu ceisiwch ei drwsio drwy briodweddau'r ffolder.
+filterFolderWriteFailed=Nid oedd modd i'r negeseuon gael eu hidlo i ffolder '%S' oherwydd i ysgrifennu i ffolder fethu. Gwiriwch fod gennych ddigon o le ar eich disg, a bod gennych hawl ysgrifennu i'r system ffeil, yna ceisiwch eto.
+copyMsgWriteFailed=Nid oedd modd symud na chopïo negeseuon i ffolder '%S' am i ysgrifennu i'r ffolder fethu. I gynyddu lle ar ddisg, o'r ddewislen Ffeil, yn gyntaf dewiswch Gwagio'r Sbwriel, yna dewis Cywasgu Ffolderi a wedyn ceisio eto.
+cantMoveMsgWOBodyOffline=Tra'n gweithio all-lein, nid oes modd symud na chopïo negeseuon nad ydynt wedi'u llwytho i lawr ar gyfer defnydd all-lein. O'r ffenestr E-bost, agorwch ddewislen Ffeil, dewis All-lein, yna Gweithio All-lein, a cheisio eto.
+operationFailedFolderBusy=Methodd y weithred am fod gweithred arall yn defnyddio'r ffolder. Arhoswch i'r weithred honno orffen a cheisiwch eto.
+folderRenameFailed=Nid oedd modd ailenwi'r ffolder. Efallai fod y ffolder yn cael ei ailddosrannu, neu nid yw'r enw newydd yn enw ffolder dilys.
+# LOCALIZATION NOTE(verboseFolderFormat): %1$S is folder name, %2$S is server name
+verboseFolderFormat=%1$S ar %2$S
+# LOCALIZATION NOTE(filterFolderTruncateFailed): %1$S is replaced by the folder name, %2$S is replaced by the brandShortName
+filterFolderTruncateFailed=Bu gwall wrth docio'r Blwch Derbyn ar ôl hidlo neges yn ffolder '%1$S'. Efallai bydd rhaid i chi gau %2$S a dileu INBOX.msf.
+
+mailboxTooLarge=Mae ffolder %S yn llawn ac yn methu dal rhagor. I wneud lle am ragor, dilëwch unrhyw negeseuon hen neu ddiangen a chywasgu'r ffolder.
+outOfDiskSpace=Does dim digon o le ar ddisg i lwytho eich negeseuon i lawr. Dilëwch hen bost, gwagio ffolder Sbwriel a chywasgu eich ffolderi e-bost, ac yna ceisiwch eto.
+errorGettingDB=Methu agor ffeil crynodeb %S. Efallai bod gwall ar y disg, neu fod y llwybr llawn yn rhy hir.
+defaultServerTag=(Rhagosodiad)
+
+# Used in message database list view to provide a text value for graphic based cells.
+messageUnread=Heb eu Darllen
+messageHasFlag=Serennog
+messageHasAttachment=Atodiad Ynghlwm
+messageJunk=Sbam
+messageExpanded=Estynnwyd
+messageCollapsed=Caeedig
+
+# Used in the SMTP Account Settings panel when a server value has no properties
+smtpServerList-NotSpecified=<not specified>
+smtpServer-ConnectionSecurityType-0=Dim
+smtpServer-ConnectionSecurityType-1=STARTTLS, os ar gael
+smtpServer-ConnectionSecurityType-2=STARTTLS
+smtpServer-ConnectionSecurityType-3=SSL/TLS
+smtpServers-confirmServerDeletionTitle=Dileu'r Gweinydd
+smtpServers-confirmServerDeletion=Ydych chi'n siŵr eich bod am ddileu gweinydd: \n %S?
+
+# Account Settings - Both Incoming and SMTP server
+authNo=Dim dilysiad
+authOld=Cyfrinair, dull gwreiddiol (anniogel)
+authPasswordCleartextInsecurely=Cyfrinair, wedi'i drosglwyddo'n anniogel
+authPasswordCleartextViaSSL=Cyfrinair arferol
+authPasswordEncrypted=Cyfrinair wedi'i amgryptio
+authKerberos=Kerberos / GSSAPI
+authExternal=Tystysgrif TLS
+authNTLM=NTLM
+authOAuth2=OAuth2
+authAnySecure=Unrhyw ddull diogel (anghymeradwy)
+authAny=Unrhyw ddull (anniogel)
+
+# OAuth2 window title
+# LOCALIZATION NOTE(oauth2WindowTitle):
+# %1$S is the username (or full email address) used for authentication.
+# %2$S is the hostname of the account being authenticated.
+oauth2WindowTitle=Rhowch fanylion %1$S ar %2$S
+
+# LOCALIZATION NOTE(serverType-nntp): Do not translate "NNTP" in the line below
+serverType-nntp=Gweinydd Newyddion (NNTP)
+# LOCALIZATION NOTE(serverType-pop3): Do not translate "POP" in the line below
+serverType-pop3=Gweinydd E-bost POP
+# LOCALIZATION NOTE(serverType-imap): Do not translate "IMAP" in the line below
+serverType-imap=Gweinydd E-bost IMAP
+serverType-none=Storfa E-bost Lleol
+
+sizeColumnTooltip2=Trefnu yn ôl maint
+sizeColumnHeader=Maint
+linesColumnTooltip2=Trefnu yn ôl llinellau
+linesColumnHeader=Llinellau
+
+# LOCALIZATION NOTE (getMsgButtonTooltip): Do not translate the word "%S" below.
+# Place the word "%S" in your translation where the name of the comma separated accounts should appear.
+getMsgButtonTooltip=Estyn negeseuon ar gyfer %S
+# Used to separate email addresses in a list.  Note the trailing space ', '
+getMsgButtonTooltip.listSeparator=,\u0020
+
+# status feedback stuff
+documentDone=
+documentLoading=Llwytho Neges…
+
+# LOCALIZATION NOTE (autosyncProgress): Do not translate the word "%1$S" or "%2$S" below.
+# Place the word %1$S in your translation where the name of the comma separated folders should appear.
+# Place the word %2$S in your translation where the name of the comma separated accounts should appear.
+autosyncProgress=Cydweddu negeseuon yn %1$S o %2$S…
+
+unreadMsgStatus=Heb eu darllen: %S
+selectedMsgStatus=Dewiswyd:%S
+totalMsgStatus=Cyfanswm: %S
+
+# localized folder names
+
+localFolders=Ffolderi Lleol
+
+# LOCALIZATION NOTE (inboxFolderName): OK to translate all foldernames, bugzilla #57440 & bugzilla #23625 fixed
+inboxFolderName=Blwch Derbyn
+trashFolderName=Sbwriel
+sentFolderName=Anfonwyd
+draftsFolderName=Drafftiau
+templatesFolderName=Templedi
+outboxFolderName=Blwch Anfon
+junkFolderName=Sbam
+archivesFolderName=Archifau
+
+# "Normal" priority is often blank,
+# depending on the consumers of these strings
+priorityLowest=Isaf
+priorityLow=Isel
+priorityNormal=Arferol
+priorityHigh=Uchel
+priorityHighest=Uchaf
+
+#Group by date thread pane titles
+today=Heddiw
+yesterday=Ddoe
+lastWeek=Wythnos Diwethaf
+last7Days=7 Diwrnod Diwethaf
+twoWeeksAgo=Pythefnos yn Ôl
+last14Days=14 Diwrnod Diwethaf
+older=Hŷn
+futureDate=Y Dyfodol
+
+#Grouped By Tags
+untaggedMessages=Negeseuon heb eu Tagio
+
+# Grouped by status
+messagesWithNoStatus=Dim Statws
+
+#Grouped by priority
+noPriority=Dim Blaenoriaeth
+
+#Grouped by has attachments
+noAttachments=Dim Atodiad
+attachments=Atodiadau
+
+#Grouped by starred
+notFlagged=Dim Serenog
+groupFlagged=Serennog
+
+# defaults descriptions for tag prefs listed in mailnews.js
+# (we keep the .labels. names for backwards compatibility)
+mailnews.tags.remove=Tynnu Pob Tag
+mailnews.labels.description.1=Pwysig
+mailnews.labels.description.2=Gwaith
+mailnews.labels.description.3=Personol
+mailnews.labels.description.4=I'w Gwneud
+mailnews.labels.description.5=Diweddarach
+
+# Format definition tag menu texts.
+# This is necessary in order to get the accesskeys to be the on the first
+# character of the menu text instead of after the menu text.
+# If a key definition exists for the tag at index n, that key's key will be
+# taken as the accesskey, eg.
+#   <key id="key_tag3" key="&tagCmd3.key;" oncommand="ToggleMessageTagKey(3);"/>
+# makes the third tag have the accesskey &tagCmd3.key;.
+# In the menuitem's label, this accesskey appears at %1$S below; %2$S will be
+# replaced by the tag label.
+mailnews.tags.format=%1$S %2$S
+
+replied=Atebwyd
+forwarded=Anfonwyd Ymlaen
+redirected=Ailgyfeiriwyd
+new=Newydd
+read=Darllenwyd
+flagged=Serennog
+
+# for junk status picker in search and mail views
+junk=Sbam
+
+# for junk score origin picker in search and mail views
+junkScoreOriginPlugin=Ategyn
+junkScoreOriginFilter=Hidl
+junkScoreOriginWhitelist=Rhestr Wen
+junkScoreOriginUser=Defnyddiwr
+junkScoreOriginImapFlag=Baner IMAP
+
+# for the has attachment picker in search and mail views
+hasAttachments=Atodiadau Ynghlwm
+
+# for the Tag picker in search and mail views.
+tag=Tagiau
+
+# LOCALIZATION NOTE(andOthers):
+# for multiple authors, add this abbreviation to the first author to indicate
+# there are more; for the From column in the threadpane message list.
+andOthers=et al.
+
+# whether to also show phonetic fields in the addressbook
+# LOCALIZATION NOTE(mail.addr_book.show_phonetic_fields):
+# the only valid values are: true OR false (choose from the untranslated English words)
+mail.addr_book.show_phonetic_fields=false
+
+# valid format options are:
+# 1: yyyy/mm/dd
+# 2: yyyy/dd/mm
+# 3: mm/dd/yyyy
+# 4: mm/yyyy/dd
+# 5: dd/mm/yyyy
+# 6: dd/yyyy/mm
+#
+# 0: auto-detect the current locale format
+#    a separator has to be either '/', '-', '.' and the year in Christian year
+#    otherwise mm/dd/yyyy (option 3) is used
+#
+mailnews.search_date_format=0
+# separator for search date (e.g. "/", "-"), or empty when search_date_format is zero
+mailnews.search_date_separator=
+# leading zeros for day and month values, not used if mailnews.search_date_format is not zero
+mailnews.search_date_leading_zeros=true
+
+# offline msg
+nocachedbodybody2=Nid yw corff y neges wedi cael ei llwytho i lawr o'r gweinydd ar gyfer darllen all-lein. I ddarllen y neges rhaid i chi ail gysylltu â'r rhwydwaith, dewis All-lein o'r ddewislen Ffeil ac yna dad-dewis Gweithio All-lein. Yn y dyfodol, gallwch ddewis pa neges neu ffolder i'w ddarllen all-lein. I wneud hyn, dewiswch All-lein o'r ddewislen ffeil ac yna dewis Llwytho i Lawr/Cydweddu Nawr. Gallwch newid Lle ar Ddisg i atal llwytho negeseuon mawr i lawr.
+
+# LOCALIZATION NOTE(acctCentralTitleFormat): %1$S is brand, %2$S is account type, %3$S is account name
+acctCentralTitleFormat=%1$S %2$S - %3$S
+mailAcctType=E-bost
+newsAcctType=Newyddion
+feedsAcctType=Llif
+
+# LOCALIZATION NOTE(nocachedbodytitle): Do not translate "<TITLE>" or "</TITLE>" in the line below
+nocachedbodytitle=<TITLE>Ewch Ar-lein i Ddarllen y Neges Hon</TITLE>\n
+
+# mailWindowOverlay.js
+confirmUnsubscribeTitle=Cadarnhau Dad-danysgrifio
+confirmUnsubscribeText=Ydych chi'n siŵr eich bod am ddad-danysgrifio o %S?
+confirmUnsubscribeManyText=Ydych chi'n siŵr eich bod am ddad-danysgrifio o'r grwpiau newyddion hyn?
+restoreAllTabs=Adfer Pob Tab
+
+confirmMarkAllFoldersReadTitle=Marcio Pob Ffolder Wedi'u Darllen
+confirmMarkAllFoldersReadMessage=Ydych chi'n siŵr eich bod am farcio pob neges ym mhob ffolder o'r cyfrif hwn fel wedi'i darllen?
+
+# LOCALIZATION NOTE(junkBarMessage): %S is brand
+junkBarMessage=Mae %S yn meddwl mai Sbam yw'r neges hon.
+junkBarButton=Nid Sbam
+junkBarButtonKey=N
+junkBarInfoButton=Dysgu Rhagor
+junkBarInfoButtonKey=R
+
+# LOCALIZATION NOTE(remoteContentBarMessage): %S is brand
+remoteContentBarMessage=I ddiogelu eich preifatrwydd, mae %S wedi rhwystro delweddau pell yn y neges.
+remoteContentPrefLabel=Dewisiadau
+remoteContentPrefAccesskey=D
+remoteContentPrefLabelUnix=Dewisiadau
+remoteContentPrefAccesskeyUnix=D
+
+# LOCALIZATION NOTE(remoteAllowResource): %S is origin
+remoteAllowResource=Caniatáu cynnwys pell o %S
+# LOCALIZATION NOTE(remoteAllowAll): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# #1 is the number of origins
+remoteAllowAll=Peidio â chaniatáu cynnwys pell o'r ffynonellau uchod;Caniatáu cynnwys pell o'r #1 ffynhonnell uchod;Caniatáu cynnwys pell o'r #1 ffynhonnell uchod;Caniatáu cynnwys pell o'r #1 ffynhonnell uchod;Caniatáu cynnwys pell o'r #1 ffynhonnell uchod;Caniatáu cynnwys pell o'r #1 ffynhonnell uchod
+
+phishingBarMessage=Efallai mai ffugiad yw'r neges hon.
+phishingBarPrefLabel=Dewisiadau
+phishingBarPrefAccesskey=e
+phishingBarPrefLabelUnix=Dewisiadau
+phishingBarPrefAccesskeyUnix=d
+
+mdnBarIgnoreButton=Anwybyddu'r Cais
+mdnBarIgnoreButtonKey=n
+mdnBarSendReqButton=Anfon Derbynneb
+mdnBarSendReqButtonKey=A
+
+draftMessageMsg=Neges ddrafft yw hon.
+draftMessageButton=Golygu
+draftMessageButtonKey=G
+
+# msgHdrViewOverlay.js
+openLabel=Agor
+openLabelAccesskey=O
+saveLabel=Cadw Fel…
+saveLabelAccesskey=A
+detachLabel=Datod…
+detachLabelAccesskey=D
+deleteLabel=Dileu
+deleteLabelAccesskey=E
+openFolderLabel=Agor Ffolder Cynhwysol
+openFolderLabelAccesskey=F
+deleteAttachments=Bydd yr atodiadau canlynol yn cael eu dileu'n barhaol o neges:\n%S\nNid oes modd dadwneud y weithred hon. Hoffech chi barhau?
+detachAttachments=Mae'r atodiadau canlynol wedi'u cadw'n llwyddiannus a byddant yn cael eu dileu o'r neges yn barhaol:\n%S\nNid oes modd dadwneud y weithred hon. Hoffech chi barhau?
+deleteAttachmentFailure=Methu dileu'r atodiad yma.
+emptyAttachment=Mae'r atodiad yma i weld yn wag.\nGwiriwch gyda'r person anfonodd hwn.\nYn aml mae muriau tân neu raglenni gwrth firws yn dinistrio atodiadau.
+externalAttachmentNotFound=Nid yw'r ffeil ar wahân hon neu atodiad dolen wedi ei ganfod neu nid yw'n hygyrch yn y lleoliad hwn bellach.
+
+# LOCALIZATION NOTE (attachmentCount): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# #1 number of attachments
+attachmentCount=Dim atodiadau;#1 atodiad;#1 atodiad;#1 atodiad;#1 atodiad;#1 atodiad
+
+# LOCALIZATION NOTE (attachmentCountSingle): This is the format for the
+# attachment header when a message has only one attachment. This is separate
+# from attachmentCount above, since attachmentCountSingle typically ends with a
+# colon.
+attachmentCountSingle=1 atodiad:
+
+# LOCALIZATION NOTE (attachmentSizeUnknown): The string to show for the total
+# size of all attachments when none of the attachments' sizes can be detected.
+attachmentSizeUnknown=maint anhysbys
+
+# LOCALIZATION NOTE (attachmentSizeAtLeast): The string to show for the total
+# size of all attachments when at least one (but not all) of the attachments'
+# sizes can't be detected. %1$S is the formatted size.
+attachmentSizeAtLeast=o leiaf %1$S
+
+# This is the format for prepending accesskeys to the
+# each of the attachments in the file|attachments menu:
+#   ie: 1 file.txt
+#       2 another file.txt
+attachmentDisplayNameFormat=%S %S
+
+# This is the heading for the attachment summary when printing an email
+attachmentsPrintHeader=Atodiadau:
+
+# Connection Error Messages
+# LOCALIZATION NOTE(unknownHostError): %S is the server name
+unknownHostError=Methwyd cysylltu â gweinydd %S.
+# LOCALIZATION NOTE(connectionRefusedError): %S is the server name
+connectionRefusedError=Methwyd cysylltu â gweinydd %S; gwrthodwyd y cysylltiad.
+# LOCALIZATION NOTE(netTimeoutError): %S is the server name
+netTimeoutError=Cyfnod cyswllt i weinydd %S wedi dod i ben.
+# LOCALIZATION NOTE(netResetError): %S is the server name
+netResetError=Cafodd cysylltiad â gweinydd %S ei ailosod.
+# LOCALIZATION NOTE(netInterruptError): %S is the server name
+netInterruptError=Cafodd cysylltiad â gweinydd %S ei darfu.
+
+recipientSearchCriteria=Mae'r Testun neu'r Derbynnydd yn cynnwys:
+fromSearchCriteria=Mae'r Pwnc neu'r Anfonwr yn cynnwys:
+
+# LOCALIZATION NOTE(biffNotification): %1$S is the number of new messages
+biffNotification_message=%1$S neges newydd
+biffNotification_messages=%1$S neges newydd
+
+# LOCALIZATION NOTE(newMailNotification_message): %1$S is the name of the account %2$S is the number of new messages
+newMailNotification_message=Mae %1$S wedi derbyn %2$S neges newydd
+
+# LOCALIZATION NOTE(newMailNotification_messages): %1$S is the name of the account %2$S is the number of new messages
+newMailNotification_messages=Mae %1$S wedi derbyn %2$S neges newydd
+
+# LOCALIZATION NOTE(newMailNotification_messagetitle): %1$S is subject of new message and %2$S is sender of new message.
+# This is UNIX only
+newMailNotification_messagetitle=%1$S o %2$S
+
+# LOCALIZATION NOTE(newMailAlert_message):
+# Semi-colon list of plural forms. See:
+# https://developer.mozilla.org/en/docs/Localization_and_Plurals
+# #1 is the name of the account, #2 is the number of new messages
+newMailAlert_message=Nid yw #1 wedi derbyn negeseuon newydd;#1 wedi derbyn #2 neges newydd;#1 wedi derbyn #2 neges newydd;#1 wedi derbyn #2 neges newydd;#1 wedi derbyn #2 neges newydd;#1 wedi derbyn #2 neges newydd
+
+# For the Quota tab in the mail folder properties dialog
+quotaPercentUsed=%S%% yn llawn
+# for quota in main window (commandglue.js)
+percent=%S%%
+quotaTooltip2=Cwota IMAP: mae %S KB wedi'i ddefnyddio allan o gyfanswm o %S KB. Cliciwch am fanylion.
+
+# for message views
+confirmViewDeleteTitle=Cadarnhau
+confirmViewDeleteMessage=Ydych chi'n siŵr eich bod am ddileu'r olwg yma?
+
+# for virtual folders
+confirmSavedSearchTitle=Cadarnhau Dileu
+confirmSavedSearchDeleteMessage=Ydych chi'n siŵr eich bod am ddileu'r chwilio a gadwyd?
+
+## @name ENTER_PASSWORD_PROMPT
+## @loc None
+# LOCALIZATION NOTE (passwordPrompt): Do not translate the word %S below.
+# Place the word "%S" in your translation where the email address
+# or the username should appear
+passwordPrompt=Rhowch gyfrinair ar gyfer %1$S ar %2$S:
+
+## @name ENTER_PASSWORD_PROMPT_TITLE
+## @loc None
+passwordTitle=Mae angen Cyfrinair gweinydd E-bost
+
+# for checking if the user really wants to open lots of messages in separate windows.
+openWindowWarningTitle=Cadarnhau
+# LOCALIZATION NOTE (openWindowWarningConfirmation): Semi-colon list of plural forms.
+# #1 is the number of messages the user is attempting to open.
+openWindowWarningConfirmation=Efallai bydd agor #1 neges yn araf. Parhau?;Efallai bydd agor #1neges yn araf. Parhau?
+
+# for checking if the user really wants to open lots of messages in tabs.
+openTabWarningTitle=Cadarnhau
+# LOCALIZATION NOTE (openTabWarningConfirmation): Semi-colon list of plural forms.
+# #1 is the number of messages the user is attempting to open.
+openTabWarningConfirmation=Efallai bydd agor #1 neges yn araf. Parhau?;Efallai bydd agor #1neges yn araf. Parhau?
+
+# for warning the user that a tag they're trying to create already exists
+tagExists=Mae tag o'r enw yna'n bodoli eisoes.
+
+# title of the edit tag dialog
+editTagTitle=Golygu Tag
+
+# for the virtual folder list dialog title
+# %S is the name of the saved search folder
+editVirtualFolderPropertiesTitle=Golygu Priodweddau Chwilio a Gadwyd ar gyfer %S
+# LOCALIZATION NOTE (foldersChosen): #1 number of chosen folders
+virtualFolderSourcesChosen=Wedi dewis #1 ffolder;Wedi dewis #1 ffolder
+
+#alert to inform the user to choose one or more folders to search for a saved search folder
+alertNoSearchFoldersSelected=Rhaid dewis o leiaf un ffolder i chwilio am y ffolder chwilio a gadwyd.
+
+# These are displayed in the message and folder pane windows
+# LOCALIZATION NOTE %.*f is the abbreviated size in the appropriate units
+byteAbbreviation2=%.*f beit
+kiloByteAbbreviation2=%.*f KB
+megaByteAbbreviation2=%.*f MB
+gigaByteAbbreviation2=%.*f GB
+teraByteAbbreviation2=%.*f TB
+petaByteAbbreviation2=%.*f PB
+
+## LOCALIZATION NOTE(folderWithAccount):
+## This is used to show folder name together with an account name.
+## %1$S = folder name
+## %2$S = account name
+folderWithAccount=%1$S - %2$S
+## LOCALIZATION NOTE(folderWithUnreadMsgs):
+## This is a concatenation of two strings to compose a folder label with unread messages.
+## %1$S = folder name
+## %2$S = count of unread messages
+folderWithUnreadMsgs=%1$S (%2$S)
+## LOCALIZATION NOTE(summarizedValue):
+## This string shows an indication that the value shown is actually a summary
+## accumulated from all subfolders.
+## %S = summarized value from all subfolders
+folderSummarizedSymbolValue=▾%S
+## LOCALIZATION NOTE(subfoldersExplanation):
+## This is a tooltip message shown on the values in the numeric folder pane columns.
+## %1$S = is the count of messages having the respective property, found in the folder under mouse cursor
+## %2$S = is the count of messages having the respective property, found in subfolders of the folder under mouse cursor
+subfoldersExplanation=%1$S yn y ffolder hwn, %2$S mewn isffolderi
+
+# Error message if message for a message id wasn't found
+errorOpenMessageForMessageIdTitle=Gwall wrth agor message-id
+errorOpenMessageForMessageIdMessage=Heb ganfod message-id %S
+
+# Warnings to alert users about phishing urls
+confirmPhishingTitle=Rhybudd E-bost Twyllodrus
+linkMismatchTitle=Wedi canfod Dolenni Anghydweddus
+#LOCALIZATION NOTE %1$S is the brand name, %2$S is the host name of the url being visited
+confirmPhishingUrl=Mae %1$S yn meddwl mai twyll yw'r neges hon. Gall fod y dolenni yn ceisio efelychu tudalennau gwe rydych am ymweld â nhw. Ydych chi'n siŵr eich bod am ymweld â %2$S?
+#LOCALIZATION NOTE %1$S is the host name of indicated host, %2$S is the host name of the actual host.
+confirmPhishingUrlAlternate=Mae'n ymddangos bod y ddolen rydych newydd glicio arni yn mynd i at wefan gwahanol i'r hyn mae testun y ddolen yn ei ddangos. Weithiau mae hyn yn cael ei defnyddio i dracio a ydych wedi clicio ar y ddolen, ond gall hefyd fod yn sgam.\n\n Mae testun y ddolen yn awgrymu fod y ddolen yn mynd i %1$S, ond i %2$S mae'n mynd.
+#LOCALIZATION NOTE $1$S is the host name of the indicated host.
+confirmPhishingGoAhead=Mynd i %1$S beth bynnag
+#LOCALIZATION NOTE %1$S is the host name that was displayed to the user.
+confirmPhishingGoDirect=Mynd i %1$S
+
+# Check for Updates
+# LOCALIZATION NOTE (updatesItem_*): these are alternative labels for Check for Update item in Help menu.
+# Which one is used depends on Update process state.
+updatesItem_default=Gwirio am Ddiweddariadau…
+updatesItem_defaultFallback=Gwirio am Ddiweddariadau…
+updatesItem_default.accesskey=G
+updatesItem_downloading=Llwytho %S i Lawr…
+updatesItem_downloadingFallback=Llwytho'r Diweddariad i Lawr…
+updatesItem_downloading.accesskey=L
+updatesItem_resume=Ail-ddechrau Llwytho %S i Lawr…
+updatesItem_resumeFallback=Ail-ddechrau Llwytho'r Diweddariad i Lawr…
+updatesItem_resume.accesskey=A
+updatesItem_pending=Gosod y Diweddariad Nawr…
+updatesItem_pendingFallback=Gosod y Diweddariad Nawr…
+updatesItem_pending.accesskey=G
+
+# Folder Pane Header Title Strings
+folderPaneModeHeader_all=Pob Ffolder
+folderPaneModeHeader_unread=Ffolderi Heb eu Darllen
+folderPaneModeHeader_favorite=Hoff Ffolderi
+folderPaneModeHeader_recent=Ffolderi Diweddar
+folderPaneModeHeader_smart=Ffolderi a Unwyd
+unifiedAccountName=Ffolderi a Unwyd
+
+# Copy / Move to Folder Again
+#LOCALIZATION NOTE %1$S is the name of the folder we will move to. moveToFolderAgainAccessKey
+# should have the same value as copyToFolderAgainAccessKey as they are the same menu item in the UI
+# moveToFolderAgainAccessKey should also be a letter that occurs before %1$S
+moveToFolderAgain=Symud i "%1$S" Eto
+moveToFolderAgainAccessKey=t
+#LOCALIZATION NOTE %1$S is the name of the folder we will copy to
+# copyToFolderAgainAccessKey
+# should have the same value as moveToFolderAgainAccessKey as they are the same menu item in the UI
+# copyToFolderAgainAccessKey should also be a letter that occurs before %1$S
+copyToFolderAgain=Copïo i "%1$S" Eto
+copyToFolderAgainAccessKey=t
+
+#LOCALIZATION NOTE(mdnBarMessageNormal) %1$S is the name of the sender
+mdnBarMessageNormal=Mae %1$S wedi gofyn i gael ei hysbysu pan fyddwch wedi darllen y neges.
+#LOCALIZATION NOTE(mdnBarMessageAddressDiffers) %1$S is the name of the sender, %2$S is the address(es) to send return receipt to
+mdnBarMessageAddressDiffers=Mae %1$S wedi gofyn i gael ei hysbysu (ar %2$S) pan fyddwch wedi darllen y neges.
+
+# mailCommands.js
+emptyJunkFolderTitle=Gwagio "%S"
+emptyJunkFolderMessage=Dileu pob neges ac is-ffolder yn y ffolder Sbam?
+emptyJunkDontAsk=Peidio â gofyn i mi eto.
+emptyTrashFolderTitle=Gwagio "%S"
+emptyTrashFolderMessage=Dileu pob neges ac is-ffolder yn y ffolder Sbwriel?
+emptyTrashDontAsk=Peidio â gofyn i mi eto.
+
+# junkCommands.js
+junkAnalysisPercentComplete=Dadansoddi sbam, cwblhau %S
+processingJunkMessages=Prosesu Negeseuon Sbam
+
+# Messenger bootstrapping messages
+fileNotFoundTitle = Heb Ganfod Ffeil
+#LOCALIZATION NOTE(fileNotFoundMsg): %S is the filename
+fileNotFoundMsg = Nid yw ffeil %S yn bodoli.
+
+fileEmptyTitle = Ffeil Gwag
+#LOCALIZATION NOTE(fileEmptyMsg): %S is the filename
+fileEmptyMsg = Mae ffeil %S yn wag.
+
+# LOCALIZATION NOTE (headerMoreAddrs): semicolon separated list of plural
+# forms of the word "more" as used after the number of addresses
+# currently hidden while displaying a header such as "to", "cc", or "bcc"
+# in the message header box.  English has two identical forms here, so it will
+# construct strings that look like (for example) "1 more" or "20 more".
+# <https://developer.mozilla.org/en/Localization_and_Plurals> has details
+# on this mechanism.
+headerMoreAddrs=Dim yn rhagor;#1 yn rhagor;#1 yn rhagor;#1 yn rhagor;#1 yn rhagor;#1 yn rhagor
+
+# LOCALIZATION NOTE (headerMoreAddrsTooltip): semicolon separated list of
+# plural forms of the phrase ", and #1 more" as used in the tooltip text
+# of the more widget displayed in the header pane (see headerMoreAddrs).
+# English has two identical forms here, so it will construct strings that
+# look like (for example) ", and 1 more" or ", and 20 more".
+# <https://developer.mozilla.org/en/Localization_and_Plurals> has details
+# on this mechanism.
+headerMoreAddrsTooltip=, a dim yn rhagor;, a #1 yn rhagor;, a #1 yn rhagor;, a #1 yn rhagor;, a #1 yn rhagor;, a #1 yn rhagor
+
+# LOCALIZATION NOTE (headertoFieldMe): first person prepositional object
+# pronoun used in the "to" header of the message header pane.  This is also
+# used for the fallback case if a header-specific localization is not
+# available.
+headertoFieldMe=Fi
+
+# LOCALIZATION NOTE (headerfromFieldMe): first person prepositional object
+# pronoun used in the "from" header of the message header pane.
+headerfromFieldMe=Fi
+
+# LOCALIZATION NOTE (headerreply-toFieldMe): first person prepositional
+# object pronoun used in the "reply-to" header of the message header pane.
+headerreply-toFieldMe=Fi
+
+# LOCALIZATION NOTE (headerccFieldMe): first person prepositional object
+# pronoun used in the "cc" header of the message header pane.
+headerccFieldMe=Fi
+
+# LOCALIZATION NOTE (headerbccFieldMe): first person prepositional object
+# pronoun used in the "bcc" header of the message header pane.
+headerbccFieldMe=Fi
+
+expandAttachmentPaneTooltip=Dangos y paen atodiad
+collapseAttachmentPaneTooltip=Cuddio'r paen atodiad
+
+# Shown when content tabs are being loaded.
+loadingTab=Llwytho…
+
+confirmMsgDelete.title=Cadarnhau Dileu
+confirmMsgDelete.collapsed.desc=Bydd hyn yn dileu negeseuon mewn edafedd caeedig. Ydych chi'n siŵr eich bod am barhau?
+confirmMsgDelete.deleteNoTrash.desc=Bydd hwn yn cael ei ddileu'n syth, heb gadw copi i'r Sbwriel. Ydych chi'n siŵr eich bod am barhau?
+confirmMsgDelete.deleteFromTrash.desc=Bydd hyn yn dileu'r neges yn barhaol o'r Sbwriel. Hoffech chi barhau?
+confirmMsgDelete.dontAsk.label=Peidio â gofyn i mi eto.
+confirmMsgDelete.delete.label=Dileu
+
+mailServerLoginFailedTitle=Methodd Mewngofndi
+# LOCALIZATION NOTE (mailServerLoginFailedTitleWithAccount):
+# "%S" is the account name.
+mailServerLoginFailedTitleWithAccount=Methodd mewngofnodi i gyfrif "%S"
+# LOCALIZATION NOTE (mailServerLoginFailed2):
+# %1$S is the host name of the server, %2$S is the user name.
+mailServerLoginFailed2=Methodd mewngofnodi i weinydd %1$S gydag enw defnyddiwr %2$S.
+mailServerLoginFailedRetryButton=&Ceisio eto
+mailServerLoginFailedEnterNewPasswordButton=&Cynnig Cyfrinair Newydd
+
+# LOCALIZATION NOTE (threadPane.columnPicker.confirmFolder.noChildren.title):
+# When the user selects a folder to apply the currently displayed columns to
+# via the "columnPicker.applyToFolder.label" menu option, this is the title of
+# the confirmation dialog used to verify they selected the correct folder.  This
+# is the case in which we apply the columns only to the folder and not to any of
+# its children.
+threadPane.columnPicker.confirmFolder.noChildren.title=Gosod y Newidiadau?
+# LOCALIZATION NOTE (threadPane.columnPicker.confirmFolder.noChildren.message):
+# When the user selects a folder to apply the currently displayed columns to
+# via the "columnPicker.applyToFolder.label" menu option, this is the text of
+# the confirmation dialog used to verify they selected the correct folder.  The
+# string '%S' is replaced with the name of the folder the user selected in
+# order to help them confirm they picked what they thought they picked.  This
+# is the case in which we apply the columns only to the folder and not to any of
+# its children.
+threadPane.columnPicker.confirmFolder.noChildren.message=Gosod colofnau cyfredol y ffolder i %S?
+
+# LOCALIZATION NOTE (threadPane.columnPicker.confirmFolder.withChildren.title):
+# When the user selects a folder to apply the currently displayed columns to via
+# the "columnPicker.applyToFolderAndChildren.label" menu option, this is the
+# title of the confirmation dialog used to verify they selected the correct
+# folder.  This is the case in which we apply the columns to the folder and all
+# of its children.
+threadPane.columnPicker.confirmFolder.withChildren.title=Gosod y Newidiadau?
+# LOCALIZATION NOTE (threadPane.columnPicker.confirmFolder.withChildren.message):
+# When the user selects a folder to apply the currently displayed columns to via
+# the "columnPicker.applyToFolderAndChildren.label" menu option, this is the
+# text of the confirmation dialog used to verify they selected the correct
+# folder.  The string '%S' is replaced with the name of the folder the user
+# selected in order to help them confirm they picked what they thought they
+# picked.  This is the case in which we apply the columns to the folder and all
+# of its children.
+threadPane.columnPicker.confirmFolder.withChildren.message=Gosod colofnau'r ffolder gyfredol i %S a'i blant?
+
+# LOCALIZATION NOTE (lwthemeInstallRequest.message): %S will be replaced with
+# the host name of the site.
+lwthemeInstallRequest.message=Mae gwefan (%S) wedi ceisio gosod thema.
+lwthemeInstallRequest.allowButton=Caniatáu
+lwthemeInstallRequest.allowButton.accesskey=n
+
+lwthemePostInstallNotification.message=Mae thema newydd wedi'i gosod.
+lwthemePostInstallNotification.undoButton=Dadwneud
+lwthemePostInstallNotification.undoButton.accesskey=U
+lwthemePostInstallNotification.manageButton=Rheoli Themâu…
+lwthemePostInstallNotification.manageButton.accesskey=R
+
+# troubleshootModeRestart
+troubleshootModeRestartPromptTitle=Ailgychwyn yn y Modd Datrys Problemau
+troubleshootModeRestartPromptMessage=Bydd y Modd Datrys Problemau'n analluogi'r holl ychwanegion ac yn defnyddio rhai dewisiadau rhagosodedig dros dro.\nYdych chi'n siŵr eich bod eisiau ailgychwyn?
+troubleshootModeRestartButton=Ailgychwyn
+
+# LOCALIZATION NOTE (downloadAndInstallButton.label): %S is replaced by the
+# version of the update: "Update to 28.0".
+update.downloadAndInstallButton.label=Diweddaru i %S
+update.downloadAndInstallButton.accesskey=D
+
+# Sanitize
+# LOCALIZATION NOTE (sanitizeDialog2.everything.title): When "Time range to
+# clear" is set to "Everything", the Clear Recent History dialog's title is
+# changed to this.  See UI mockup and comment 11 at bug 480169 -->
+sanitizeDialog2.everything.title=Clirio'r Holl Hanes
+sanitizeButtonOK=Clirio Nawr
+# LOCALIZATION NOTE (sanitizeEverythingWarning2): Warning that appears when
+# "Time range to clear" is set to "Everything" in Clear Recent History dialog,
+# provided that the user has not modified the default set of history items to clear.
+sanitizeEverythingWarning2=Bydd yr holl hanes yn cael ei glirio.
+# LOCALIZATION NOTE (sanitizeSelectedWarning): Warning that appears when
+# "Time range to clear" is set to "Everything" in Clear Recent History dialog,
+# provided that the user has modified the default set of history items to clear.
+sanitizeSelectedWarning=Bydd yr holl eitemau a ddewiswyd yn cael eu clirio.
+
+learnMoreAboutIgnoreThread=Dysgu Rhagor…
+learnMoreAboutIgnoreThreadAccessKey = S
+undoIgnoreThread=Dadwneud Anwybyddu Edefyn
+undoIgnoreThreadAccessKey=U
+undoIgnoreSubthread=Dadwneud Anwybyddu Isedefyn
+undoIgnoreSubthreadAccessKey=U
+# LOCALIZATION NOTE (ignoredThreadFeedback): #1 is the message thread title
+ignoredThreadFeedback=Ni fydd atebion i edefyn "#1" yn cael eu dangos.
+# LOCALIZATION NOTE (ignoredSubthreadFeedback): #1 is the message subthread title
+ignoredSubthreadFeedback=Ni fydd atebion i is drywydd "#1" yn cael eu dangos.
+# LOCALIZATION NOTE (ignoredThreadsFeedback): Semi-colon list of plural forms.
+# #1 is the number of threads
+ignoredThreadsFeedback=Ni fydd atebion i'r trywydd dangoswyd yn cael eu dangos.;Ni fydd atebion i'r #1 trywydd dangoswyd yn cael eu dangos.
+# LOCALIZATION NOTE (ignoredSubthreadsFeedback): Semi-colon list of plural forms.
+# #1 is number of subthreads
+ignoredSubthreadsFeedback=Ni fydd atebion i'r trywydd dangoswyd yn cael eu dangos.;Ni fydd atebion i'r #1 trywydd dangoswyd yn cael eu dangos.
+# LOCALIZATION NOTE (saveAsType): replace %S with the extension of the file to be saved.
+saveAsType=Ffeil %S
+
+# LOCALIZATION NOTE (openSearch.label): The label used in the autocomplete
+# widget to refer to a search on the web for a short string containing at most
+# 15 characters. %1$S is the search provider to use. %2$S is the string to
+# search for.
+openSearch.label=Chwilio %1$S am "%2$S"
+
+# LOCALIZATION NOTE (openSearch.label.truncated): The label used in the
+# autocomplete widget to refer to a search on the web for a short string
+# containing more than 15 characters. %1$S is the search provider to use. %2$S
+# is the string to search for, truncated to 15 characters.
+openSearch.label.truncated=Chwilio %1$S am "%2$S"
+
+# LOCALIZATION NOTE (aboutDialog.architecture.*):
+# The sixtyFourBit and thirtyTwoBit strings describe the architecture of the
+# current Thunderbird build: 32-bit or 64-bit. These strings are used in parentheses
+# after the Thunderbird version in the About dialog,
+# e.g.: "48.0.2 (32-bit)" or "51.0a1 (2016-09-05) (64-bit)".
+aboutDialog.architecture.sixtyFourBit = 64 did
+aboutDialog.architecture.thirtyTwoBit = 32 did
+
+errorConsoleTitle = Consol Gwall
+
+# LOCALIZATION NOTE (panel.back):
+# This is used by screen readers to label the "back" button in various browser
+# popup panels, including the sliding subviews of the appmenu.
+panel.back = Nôl
+
+# LOCALIZATION NOTE (folderErrorAlertTitle):
+# %S is a pretty string to identify the folder and account.
+# EXAMPLE: Error - Inbox on bob@example.com
+folderErrorAlertTitle = Gwall - %S
+
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EdAdvancedEdit.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EdAdvancedEdit.dtd
new file mode 100644
index 0000000000..3521a919ef
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EdAdvancedEdit.dtd
@@ -0,0 +1,18 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY WindowTitle.label              "Golygydd Priodwedd Uwch">
+<!ENTITY AttName.label                  "Priodoledd: ">
+<!ENTITY AttValue.label                 "Gwerth: ">
+<!ENTITY PropertyName.label             "Priodwedd: ">
+<!ENTITY currentattributesfor.label     "Priodweddau cyfredol: ">
+<!ENTITY tree.attributeHeader.label     "Priodoledd">
+<!ENTITY tree.propertyHeader.label      "Priodwedd">
+<!ENTITY tree.valueHeader.label         "Gwerth">
+<!ENTITY tabHTML.label                  "Priodweddau HTML">
+<!ENTITY tabCSS.label                   "Arddull Mewn-lein">
+<!ENTITY tabJSE.label                   "Digwyddiadau JavaScript">
+
+<!ENTITY editAttribute.label    "Cliciwch ar eitem i olygu ei gwerth">
+<!ENTITY removeAttribute.label  "Tynnu">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EdColorPicker.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EdColorPicker.dtd
new file mode 100644
index 0000000000..29829fba85
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EdColorPicker.dtd
@@ -0,0 +1,22 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY windowTitle.label "Lliw">
+<!ENTITY lastPickedColor.label "Lliw dewiswyd diwethaf">
+<!ENTITY lastPickedColor.accessKey "L">
+<!ENTITY chooseColor1.label "Dewis lliw:">
+<!ENTITY chooseColor2.label "Rhoi llinyn liw HTML">
+<!ENTITY chooseColor2.accessKey "H">
+<!ENTITY setColorExample.label "(e.e.: &quot;#0000ff&quot; neu &quot;blue&quot;):">
+<!ENTITY default.label "Rhagosodiad">
+<!ENTITY default.accessKey "R">
+<!ENTITY palette.label "Palet:">
+<!ENTITY standardPalette.label "Safonol">
+<!ENTITY webPalette.label "Pob lliw gwe">
+<!ENTITY background.label "Cefndir i:">
+<!ENTITY background.accessKey "e">
+<!ENTITY table.label "Tabl">
+<!ENTITY table.accessKey "T">
+<!ENTITY cell.label "Cell(oedd)">
+<!ENTITY cell.accessKey "C">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EdConvertToTable.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EdConvertToTable.dtd
new file mode 100644
index 0000000000..d818f65eba
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EdConvertToTable.dtd
@@ -0,0 +1,15 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+
+<!ENTITY windowTitle.label "Trosi i Dabl">
+<!ENTITY instructions1.label   "Mae Cyfansoddwr yn creu rhes tabl newydd am bob paragraff yn y dewis.">
+<!ENTITY instructions2.label   "Dewiswch y nod fydd yn cael ei ddefnyddio i wahanu'r dewis yn golofnau:">
+<!ENTITY commaRadio.label      "Collnod">
+<!ENTITY spaceRadio.label      "Lle">
+<!ENTITY otherRadio.label      "Nod Arall:">
+<!ENTITY deleteCharCheck.label "Dileu nod gwahanu">
+<!ENTITY collapseSpaces.label  "Anwybyddu'r bylchau ychwanegol">
+<!ENTITY collapseSpaces.tooltip "Trosi'r bylchau cyfagos i un gwahanydd">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EdDialogOverlay.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EdDialogOverlay.dtd
new file mode 100644
index 0000000000..f924be47fc
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EdDialogOverlay.dtd
@@ -0,0 +1,17 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY AdvancedEditButton.label "Golygu Uwch…">
+<!ENTITY AdvancedEditButton.accessKey "G">
+<!ENTITY AdvancedEditButton.tooltip "Ychwanegu neu newid Priodweddau HTML, priodweddau arddulliau a JavaScript">
+<!ENTITY chooseFileButton.label "Dewis Ffeil...">
+<!ENTITY chooseFileButton.accessKey "D">
+<!ENTITY chooseFileLinkButton.label "Dewis Ffeil...">
+<!ENTITY chooseFileLinkButton.accessKey "D">
+<!ENTITY makeUrlRelative.label "Mae'r URL yn berthynol i'r lleoliad tudalen">
+<!ENTITY makeUrlRelative.accessKey "U">
+<!ENTITY makeUrlRelative.tooltip "Newid rhwng URL absoliwt a pherthynol. Rhaid cadw'r dudalen yn gyntaf cyn gwneud hyn.">
+
+<!ENTITY LinkURLEditField2.label "Rhowch leoliad tudalen gwe, ffeil leol neu ddewis Angor a Enwyd neu Bennawd o feysydd y ddewislen cyd-destun:">
+<!ENTITY LinkURLEditField2.accessKey "w">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EdNamedAnchorProperties.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EdNamedAnchorProperties.dtd
new file mode 100644
index 0000000000..510508d130
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EdNamedAnchorProperties.dtd
@@ -0,0 +1,9 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY windowTitle.label "Priodoleddau'r Angor a Enwyd">
+<!ENTITY anchorNameEditField.label "Enw'r Angor:">
+<!ENTITY anchorNameEditField.accessKey "E">
+<!ENTITY nameInput.tooltip "Rhowch enw unigryw ar gyfer yr angor (targed)">
+
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorColorProperties.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorColorProperties.dtd
new file mode 100644
index 0000000000..2dffbd577a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorColorProperties.dtd
@@ -0,0 +1,29 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+<!ENTITY windowTitle.label "Lliwiau Tudalen a Chefndir">
+<!ENTITY pageColors.label "Lliwiau Tudalen">
+<!ENTITY defaultColorsRadio.label "Lliwiau Rhagosodedig y Darllenydd (Peidio gosod lliwiau ar y dudalen)">
+<!ENTITY defaultColorsRadio.accessKey "L">
+<!ENTITY defaultColorsRadio.tooltip "Defnyddio gosodiad lliw porwr y gwyliwr (darllenydd) yn unig">
+<!ENTITY customColorsRadio.label "Defnyddio lliwiau addasu:">
+<!ENTITY customColorsRadio.accessKey "D">
+<!ENTITY customColorsRadio.tooltip "Mae'r gosodiadau lliw hyn yn drech na gosodiadau'r porwr">
+
+<!ENTITY normalText.label "Testun arferol">
+<!ENTITY normalText.accessKey "T">
+<!ENTITY linkText.label "Testun dolen">
+<!ENTITY linkText.accessKey "d">
+<!ENTITY activeLinkText.label "Cyswllt testun gweithredol">
+<!ENTITY activeLinkText.accessKey "g">
+<!ENTITY visitedLinkText.label "Testun dolen wedi ymweld">
+<!ENTITY visitedLinkText.accessKey "o">
+<!ENTITY background.label "Cefndir:">
+<!ENTITY background.accessKey "e">
+<!ENTITY colon.character ":">
+<!ENTITY backgroundImage.label "Delweddau Cefndir:">
+<!ENTITY backgroundImage.accessKey "D">
+<!ENTITY backgroundImage.tooltip "Defnyddio ffeil delwedd fel cefndir ar gyfer eich tudalen">
+<!ENTITY backgroundImage.shortenedDataURI "URI data byrrach (bydd copi'n gosod yr URI llawn ar i'r clipfwrdd)">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorHLineProperties.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorHLineProperties.dtd
new file mode 100644
index 0000000000..659a9ae24b
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorHLineProperties.dtd
@@ -0,0 +1,27 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+
+<!ENTITY windowTitle.label "Priodweddau Llinell Lorweddol">
+
+<!ENTITY dimensionsBox.label "Dimensiynau">
+<!ENTITY heightEditField.label "Uchder:">
+<!ENTITY heightEditField.accessKey "U">
+<!ENTITY widthEditField.label "Lled:">
+<!ENTITY widthEditField.accessKey "L">
+<!ENTITY pixelsPopup.value "picseli">
+<!ENTITY alignmentBox.label "Aliniad">
+<!ENTITY leftRadio.label "Chwith">
+<!ENTITY leftRadio.accessKey "C">
+<!ENTITY centerRadio.label "Canol">
+<!ENTITY centerRadio.accessKey "a">
+<!ENTITY rightRadio.label "De">
+<!ENTITY rightRadio.accessKey "D">
+
+<!ENTITY threeDShading.label "Gradd liwio 3-D">
+<!ENTITY threeDShading.accessKey "G">
+<!ENTITY saveSettings.label "Defnyddio fel Rhagosodiad">
+<!ENTITY saveSettings.accessKey "R">
+<!ENTITY saveSettings.tooltip "Cadw'r gosodiadau hyn i'w defnyddio wrth fewnosod llinellau llorweddol newydd">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorImageProperties.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorImageProperties.dtd
new file mode 100644
index 0000000000..a01b54400d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorImageProperties.dtd
@@ -0,0 +1,81 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- These strings are for use specifically in the editor's image and form image dialogs. -->
+<!-- Window title -->
+
+
+<!ENTITY windowTitle.label "Priodweddau Delwedd">
+
+<!ENTITY pixelsPopup.value "picseli">
+<!-- These are in the Location tab panel -->
+
+<!ENTITY locationEditField.label "Lleoliad delwedd:">
+<!ENTITY locationEditField.accessKey "L">
+<!ENTITY locationEditField.tooltip "Teipio enw neu leoliad ffeil y ddelwedd">
+<!ENTITY locationEditField.shortenedDataURI "URI data byrrach (bydd copi'n gosod yr URI llawn ar i'r clipfwrdd)">
+<!ENTITY title.label "Cyngor:">
+<!ENTITY title.accessKey "C">
+<!ENTITY title.tooltip "Y briodoledd 'teitl' sy'n cael ei ddangos fel cyngor">
+<!ENTITY altText.label "Testun eiledol:">
+<!ENTITY altText.accessKey "e">
+<!ENTITY altTextEditField.tooltip "Teipio testun i'w arddangos yn lle'r ddelwedd">
+<!ENTITY noAltText.label "Peidio defnyddio testun eiledol">
+<!ENTITY noAltText.accessKey "P">
+
+<!ENTITY previewBox.label "Rhagolwg Delwedd">
+
+<!-- These controls are in the Dimensions tab panel -->
+<!-- actualSize.label should be same as actualSizeRadio.label + ":" -->
+
+<!ENTITY actualSize.label "Maint Gwirioneddol:">
+<!ENTITY actualSizeRadio.label "Maint Gwirioneddol">
+<!ENTITY actualSizeRadio.accessKey "M">
+<!ENTITY actualSizeRadio.tooltip "Dychwelyd i faint gwirioneddol y ddelwedd">
+<!ENTITY customSizeRadio.label "Maint Cyfaddasu">
+<!ENTITY customSizeRadio.accessKey "a">
+<!ENTITY customSizeRadio.tooltip "Newid maint y ddelwedd fel y'i dangosir ar y dudalen">
+<!ENTITY heightEditField.label "Uchder:">
+<!ENTITY heightEditField.accessKey "U">
+<!ENTITY widthEditField.label "Lled:">
+<!ENTITY widthEditField.accessKey "L">
+<!ENTITY constrainCheckbox.label "Cyfyngu">
+<!ENTITY constrainCheckbox.accessKey "f">
+<!ENTITY constrainCheckbox.tooltip "Cadw cyfradd agwedd y ddelwedd">
+<!-- These controls are in the Image Map box of the expanded area -->
+
+<!ENTITY imagemapBox.label "Map Delwedd">
+<!ENTITY removeImageMapButton.label "Tynnu">
+<!ENTITY removeImageMapButton.accessKey "T">
+<!-- These are the options for image alignment -->
+
+<!ENTITY alignment.label "Alinio Testun i'r Ddelwedd">
+<!ENTITY bottomPopup.value "Ar y gwaelod">
+<!ENTITY topPopup.value "Ar y brig">
+<!ENTITY centerPopup.value "Yn y canol">
+<!ENTITY wrapRightPopup.value "Amlapio i'r dde">
+<!ENTITY wrapLeftPopup.value "Amlapio i'r chwith">
+<!-- These controls are in the Spacing Box -->
+
+<!ENTITY spacingBox.label "Bylchu">
+<!ENTITY leftRightEditField.label "Chwith a De:">
+<!ENTITY leftRightEditField.accessKey "h">
+<!ENTITY topBottomEditField.label "Brig a Gwaelod:">
+<!ENTITY topBottomEditField.accessKey "B">
+<!ENTITY borderEditField.label "Ymyl Solet:">
+<!ENTITY borderEditField.accessKey "Y">
+<!-- These controls are in the Link Box -->
+
+<!ENTITY showImageLinkBorder.label "Dangos ymyl o amgylch delwedd gysylltiedig">
+<!ENTITY showImageLinkBorder.accessKey "D">
+<!ENTITY LinkAdvancedEditButton.label "Dolen Golygu Uwch…">
+<!ENTITY LinkAdvancedEditButton.accessKey "D">
+<!ENTITY LinkAdvancedEditButton.tooltip "Ychwanegu neu newid Priodweddau HTML, priodoleddau arddulliau a JavaScript">
+<!-- These tabs are currently used in the image input dialog -->
+
+<!ENTITY imageInputTab.label "Ffurflen">
+<!ENTITY imageLocationTab.label "Lleoliad">
+<!ENTITY imageDimensionsTab.label "Dimensiynau">
+<!ENTITY imageAppearanceTab.label "Gwedd">
+<!ENTITY imageLinkTab.label "Dolen">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertChars.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertChars.dtd
new file mode 100644
index 0000000000..494e858a23
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertChars.dtd
@@ -0,0 +1,19 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+
+<!ENTITY windowTitle.label "Mewnosod Nod">
+<!ENTITY category.label "Categori">
+<!ENTITY letter.label "Llythyren:">
+<!ENTITY letter.accessKey "L">
+<!ENTITY character.label "Nod:">
+<!ENTITY character.accessKey "N">
+<!ENTITY accentUpper.label "Acen Priflythyren">
+<!ENTITY accentLower.label "Acen Llythyren fach">
+<!ENTITY otherUpper.label "Priflythyren Arall">
+<!ENTITY otherLower.label "Llythyren Fach Arall">
+<!ENTITY commonSymbols.label "Symbolau Cyffredin">
+<!ENTITY insertButton.label "Mewnosod">
+<!ENTITY closeButton.label "Cau">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertMath.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertMath.dtd
new file mode 100644
index 0000000000..c3533186a1
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertMath.dtd
@@ -0,0 +1,21 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+<!ENTITY windowTitle.label "Mewnosod Mathemateg">
+
+<!ENTITY sourceEditField.label "Rhosi'r cod ffynhonnell LaTeX:">
+
+<!ENTITY options.label "Dewisiadau">
+<!ENTITY optionInline.label "Modd mewnlin">
+<!ENTITY optionInline.accesskey "m">
+<!ENTITY optionDisplay.label "Modd dangos">
+<!ENTITY optionDisplay.accesskey "d">
+<!ENTITY optionLTR.label "Cyfeiriad chwith i'r dde">
+<!ENTITY optionLTR.accesskey "c">
+<!ENTITY optionRTL.label "Cyfeiriad de i'r chwith">
+<!ENTITY optionRTL.accesskey "d">
+
+<!ENTITY insertButton.label "Mewnosod">
+<!ENTITY insertButton.accesskey "M">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertSource.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertSource.dtd
new file mode 100644
index 0000000000..09877577a5
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertSource.dtd
@@ -0,0 +1,15 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+<!ENTITY windowTitle.label "Mewnosod HTML">
+<!ENTITY sourceEditField.label "Gosod tagiau HTML a thestun:">
+<!ENTITY example.label "Enghraifft: ">
+<!-- LOCALIZATION NOTE (exampleOpenTag.label): DONT_TRANSLATE: they are text for HTML tagnames: "<i>" and "</i>" -->
+<!ENTITY exampleOpenTag.label "&lt;i&gt;">
+<!-- LOCALIZATION NOTE (exampleCloseTag.label): DONT_TRANSLATE: they are text for HTML tagnames: "<i>" and "</i>" -->
+<!ENTITY exampleCloseTag.label "&lt;/i&gt;">
+<!ENTITY exampleText.label "Helo Pawb!">
+<!ENTITY insertButton.label "Mewnosod">
+<!ENTITY insertButton.accesskey "M">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertTOC.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertTOC.dtd
new file mode 100644
index 0000000000..e30f42dfb2
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertTOC.dtd
@@ -0,0 +1,16 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY Window.title        "Tabl Cynnwys">
+<!ENTITY buildToc.label      "Creu'r tabl cynnwys o:">
+<!ENTITY tag.label           "Tag:">
+<!ENTITY class.label         "Dosbarth:">
+<!ENTITY header1.label       "Lefel 1">
+<!ENTITY header2.label       "Lefel 2">
+<!ENTITY header3.label       "Lefel 3">
+<!ENTITY header4.label       "Lefel 4">
+<!ENTITY header5.label       "Lefel 5">
+<!ENTITY header6.label       "Lefel 6">
+<!ENTITY makeReadOnly.label  "Gwneud y tabl cynnwys yn darllen yn unig">
+<!ENTITY orderedList.label   "Rhifo pob cofnod yn y tabl cynnwys">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertTable.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertTable.dtd
new file mode 100644
index 0000000000..9a6acaa5f3
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorInsertTable.dtd
@@ -0,0 +1,18 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+<!ENTITY windowTitle.label "Mewnosod Tabl">
+
+<!ENTITY size.label "Maint">
+<!ENTITY numRowsEditField.label "Rhesi:">
+<!ENTITY numRowsEditField.accessKey "R">
+<!ENTITY numColumnsEditField.label "Colofnau:">
+<!ENTITY numColumnsEditField.accessKey "C">
+<!ENTITY widthEditField.label "Lled:">
+<!ENTITY widthEditField.accessKey "L">
+<!ENTITY borderEditField.label "Ymyl:">
+<!ENTITY borderEditField.accessKey "Y">
+<!ENTITY borderEditField.tooltip "Teipio rhif ar gyfer ymyl y tabl, neu deipio sero (0) am ddim ymyl">
+<!ENTITY pixels.label "picseli">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorLinkProperties.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorLinkProperties.dtd
new file mode 100644
index 0000000000..8f775351aa
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorLinkProperties.dtd
@@ -0,0 +1,6 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY windowTitle.label "Priodweddau Dolen">
+<!ENTITY LinkURLBox.label "Lleoliad Dolen">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorListProperties.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorListProperties.dtd
new file mode 100644
index 0000000000..15216ed8a2
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorListProperties.dtd
@@ -0,0 +1,20 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+
+<!ENTITY windowTitle.label "Rhestri Priodweddau">
+
+<!ENTITY ListType.label "Math Rhestr">
+<!ENTITY bulletStyle.label "Arddull Bwled:">
+<!ENTITY startingNumber.label "Cychwyn yn:">
+<!ENTITY startingNumber.accessKey "C">
+<!ENTITY none.value "Dim">
+<!ENTITY bulletList.value "Rhestr Bwled (Heb ei rhifo)">
+<!ENTITY numberList.value "Rhestr wedi'i Rhifo">
+<!ENTITY definitionList.value "Rhestr Ddiffinio">
+<!ENTITY changeEntireListRadio.label "Newid y rhestr i gyd">
+<!ENTITY changeEntireListRadio.accessKey "N">
+<!ENTITY changeSelectedRadio.label "Newid rhai eitemau yn unig">
+<!ENTITY changeSelectedRadio.accessKey "r">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorPersonalDictionary.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorPersonalDictionary.dtd
new file mode 100644
index 0000000000..d14a116c40
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorPersonalDictionary.dtd
@@ -0,0 +1,18 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+<!ENTITY windowTitle.label "Geiriadur Personol">
+
+<!ENTITY wordEditField.label "Gair newydd:">
+<!ENTITY wordEditField.accessKey "n">
+<!ENTITY AddButton.label "Ychwanegu">
+<!ENTITY AddButton.accessKey "Y">
+<!ENTITY DictionaryList.label "Geiriau yn y geiriadur:">
+<!ENTITY DictionaryList.accessKey "G">
+<!ENTITY RemoveButton.label "Tynnu">
+<!ENTITY RemoveButton.accessKey "y">
+
+<!ENTITY CloseButton.label "Cau">
+<!ENTITY CloseButton.accessKey "u">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorReplace.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorReplace.dtd
new file mode 100644
index 0000000000..af0ee89438
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorReplace.dtd
@@ -0,0 +1,29 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- extracted from EdReplace.xul -->
+
+
+<!-- extracted from EdReplace.xhtml -->
+
+<!ENTITY replaceDialog.title "Canfod a Newid">
+<!ENTITY findField.label "Canfod testun:">
+<!ENTITY findField.accesskey "C">
+<!ENTITY replaceField.label "Newid gyda:">
+<!ENTITY replaceField.accesskey "N">
+<!ENTITY caseSensitiveCheckbox.label "Cydweddu maint">
+<!ENTITY caseSensitiveCheckbox.accesskey "C">
+<!ENTITY wrapCheckbox.label "Amlapio">
+<!ENTITY wrapCheckbox.accesskey "A">
+<!ENTITY backwardsCheckbox.label "Chwilio nôl">
+<!ENTITY backwardsCheckbox.accesskey "h">
+<!ENTITY findNextButton.label "Canfod nesaf">
+<!ENTITY findNextButton.accesskey "n">
+<!ENTITY replaceButton.label "Newid">
+<!ENTITY replaceButton.accesskey "N">
+<!ENTITY replaceAndFindButton.label "Newid a Chanfod">
+<!ENTITY replaceAndFindButton.accesskey "N">
+<!ENTITY replaceAllButton.label "Newid Popeth">
+<!ENTITY replaceAllButton.accesskey "N">
+<!ENTITY closeButton.label "Cau">
+<!ENTITY closeButton.accesskey "C">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorSpellCheck.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorSpellCheck.dtd
new file mode 100644
index 0000000000..e33f37022f
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorSpellCheck.dtd
@@ -0,0 +1,38 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Window title -->
+
+<!ENTITY windowTitle.label "Gwirio Sillafu">
+
+<!ENTITY misspelledWord.label "Gair wedi'i gamsillafu:">
+<!ENTITY wordEditField.label "Newid gyda:">
+<!ENTITY wordEditField.accessKey "N">
+<!ENTITY checkwordButton.label "Gwirio Gair">
+<!ENTITY checkwordButton.accessKey "G">
+<!ENTITY suggestions.label "Awgrymiadau:">
+<!ENTITY suggestions.accessKey "A">
+<!ENTITY ignoreButton.label "Anwybyddu">
+<!ENTITY ignoreButton.accessKey "A">
+<!ENTITY ignoreAllButton.label "Anwybyddu Popeth">
+<!ENTITY ignoreAllButton.accessKey "P">
+<!ENTITY replaceButton.label "Amnewid">
+<!ENTITY replaceButton.accessKey "m">
+<!ENTITY replaceAllButton.label "Newid y Cyfan">
+<!ENTITY replaceAllButton.accessKey "y">
+<!ENTITY stopButton.label "Atal">
+<!ENTITY stopButton.accessKey "A">
+<!ENTITY userDictionary.label "Geiriadur Personol:">
+<!ENTITY moreDictionaries.label "Llwytho rhagor o eiriaduron i lawr…">
+<!ENTITY addToUserDictionaryButton.label "Ychwanegu Gair">
+<!ENTITY addToUserDictionaryButton.accessKey "G">
+<!ENTITY editUserDictionaryButton.label "Golygu…">
+<!ENTITY editUserDictionaryButton.accessKey "G">
+<!ENTITY recheckButton2.label "Ailwirio'r Testun">
+<!ENTITY recheckButton2.accessKey "T">
+<!ENTITY closeButton.label "Cau">
+<!ENTITY closeButton.accessKey "u">
+<!ENTITY sendButton.label "Anfon">
+<!ENTITY sendButton.accessKey "A">
+<!ENTITY languagePopup.label "Iaith:">
+<!ENTITY languagePopup.accessKey "I">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/EditorTableProperties.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/EditorTableProperties.dtd
new file mode 100644
index 0000000000..456758cfa6
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/EditorTableProperties.dtd
@@ -0,0 +1,75 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY tableWindow.title                "Priodoleddau Tabl">
+<!ENTITY applyButton.label                "Gosod">
+<!ENTITY applyButton.accesskey            "G">
+<!ENTITY closeButton.label                "Cau">
+<!ENTITY tableTab.label                   "Tabl">
+<!ENTITY cellTab.label                    "Celloedd">
+<!ENTITY tableRows.label                  "Rhesi:">
+<!ENTITY tableRows.accessKey              "R">
+<!ENTITY tableColumns.label               "Colofnau:">
+<!ENTITY tableColumns.accessKey           "C">
+<!ENTITY tableHeight.label                "Uchder:">
+<!ENTITY tableHeight.accessKey            "U">
+<!ENTITY tableWidth.label                 "Lled:">
+<!ENTITY tableWidth.accessKey             "L">
+<!ENTITY tableBorderSpacing.label         "Ymyl a Bylchiad">
+<!ENTITY tableBorderWidth.label           "Ymyl:">
+<!ENTITY tableBorderWidth.accessKey       "Y">
+<!ENTITY tableSpacing.label               "Bylchu:">
+<!ENTITY tableSpacing.accessKey           "B">
+<!ENTITY tablePadding.label               "Padin:">
+<!ENTITY tablePadding.accessKey           "P">
+<!ENTITY tablePxBetwCells.label           "picseli rhwng celloedd">
+<!ENTITY tablePxBetwBrdrCellContent.label "picseli rhwng border celloedd a'r cynnwys">
+<!ENTITY tableAlignment.label             "Aliniad y Tabl:">
+<!ENTITY tableAlignment.accessKey         "T">
+<!ENTITY tableCaption.label               "Pennawd:">
+<!ENTITY tableCaption.accessKey           "e">
+<!ENTITY tableCaptionAbove.label          "Uwchlaw'r Tabl">
+<!ENTITY tableCaptionBelow.label          "Islaw'r Tabl">
+<!ENTITY tableCaptionLeft.label           "Chwith y Tabl">
+<!ENTITY tableCaptionRight.label          "De'r tabl">
+<!ENTITY tableCaptionNone.label           "Dim">
+<!ENTITY tableInheritColor.label           "(Gadael i liw'r dudalen ddangos drwodd)">
+
+<!ENTITY cellSelection.label              "Dewis">
+<!ENTITY cellSelectCell.label             "Cell">
+<!ENTITY cellSelectRow.label              "Rhes">
+<!ENTITY cellSelectColumn.label           "Colofn">
+<!ENTITY cellSelectNext.label             "Nesaf">
+<!ENTITY cellSelectNext.accessKey         "N">
+<!ENTITY cellSelectPrevious.label         "Blaenorol">
+<!ENTITY cellSelectPrevious.accessKey     "B">
+<!ENTITY applyBeforeChange.label          "Bydd y newidiadau cyfredol yn cael eu gosod chyn newid y dewis.">
+<!ENTITY cellContentAlignment.label       "Aliniad Cynnwys">
+<!ENTITY cellHorizontal.label             "Llorweddol:">
+<!ENTITY cellHorizontal.accessKey         "L">
+<!ENTITY cellVertical.label               "Fertigol:">
+<!ENTITY cellVertical.accessKey           "F">
+<!ENTITY cellStyle.label                  "Arddull Cell:">
+<!ENTITY cellStyle.accessKey              "A">
+<!ENTITY cellNormal.label                 "Arferol">
+<!ENTITY cellHeader.label                 "Pennyn">
+<!ENTITY cellTextWrap.label               "Amlapio Testun:">
+<!ENTITY cellTextWrap.accessKey           "A">
+<!ENTITY cellWrap.label                   "Amlapio">
+<!ENTITY cellNoWrap.label                 "Peidio amlapio">
+<!ENTITY cellAlignTop.label               "Brig">
+<!ENTITY cellAlignMiddle.label            "Canol">
+<!ENTITY cellAlignBottom.label            "Gwaelod">
+<!ENTITY cellAlignJustify.label           "Unioni">
+<!ENTITY cellInheritColor.label           "(Gadael lliw'r tabl ddangos trwodd)">
+<!ENTITY cellUseCheckboxHelp.label        "Defnyddio blychau ticio i bennu pa briodweddau sy'n cael eu cymhwyso i bob un o'r celloedd">
+<!-- Used in both Table and Cell panels  -->
+
+<!ENTITY size.label                       "Maint">
+<!ENTITY pixels.label                     "picseli">
+<!ENTITY backgroundColor.label            "Lliw Cefndir:">
+<!ENTITY backgroundColor.accessKey        "L">
+<!ENTITY AlignLeft.label                  "Chwith">
+<!ENTITY AlignCenter.label                "Canol">
+<!ENTITY AlignRight.label                 "De">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/composeMsgs.properties b/l10n-cy/mail/chrome/messenger/messengercompose/composeMsgs.properties
new file mode 100644
index 0000000000..590689b120
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/composeMsgs.properties
@@ -0,0 +1,460 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the compose back end
+#
+## LOCALIZATION NOTE (unableToOpenFile, unableToOpenTmpFile):
+## %S will be replaced with the name of file that could not be opened
+unableToOpenFile=Methu agor ffeil %S.
+unableToOpenTmpFile=Methu agor y ffeil dros dro %S. Gwiriwch eich gosodiadau 'Cyfeiriadur Dros dro'.
+unableToSaveTemplate=Methu cadw eich neges fel templed.
+unableToSaveDraft=Methu cadw eich negeseuon ar ffurf drafft.
+couldntOpenFccFolder=Methu agor ffolder Anfonwyd. Gwiriwch fod gosodiadau'ch cyfrif e-bost yn gywir.
+noSender=Heb bennu anfonwr. Ychwanegwch eich cyfeiriad e-bost yn ngosodiadau'r cyfrif.
+noRecipients=Heb enwi derbynwyr. Rhowch dderbynnydd neu grŵp newyddion yn y maes cyfeirio.
+errorWritingFile=Gwall wrth ysgrifennu ffeil dros dro.
+
+## LOCALIZATION NOTE (errorSendingFromCommand): argument %s is the Outgoing server (SMTP) response
+errorSendingFromCommand=Cafwyd gwall wrth anfon e-bost. Ymateb y gweinydd oedd: %s. Gwiriwch fod eich cyfeiriad e-bost yn gywir yn eich dewisiadau E-bost a cheisiwch eto.
+
+## LOCALIZATION NOTE (errorSendingDataCommand): argument %s is the Outgoing server (SMTP) response
+errorSendingDataCommand=Digwyddodd gwall (SMTP) wrth anfon e-bost. Ymateb y gweinydd oedd:  %s.
+
+## LOCALIZATION NOTE (errorSendingMessage): argument %s is the Outgoing server (SMTP) response
+errorSendingMessage=Digwyddodd gwall wrth anfon e-bost. Ymateb y gweinydd oedd:   %s. Gwiriwch y neges a cheisiwch eto.
+postFailed=Nid oedd modd cofnodi'r neges am i'r cyswllt a'r gweinydd e-bost fethu. Efallai nad yw'r gweinydd ar gael neu mae'n gwrthod cysylltiadau. Gwiriwch eich gosodiadau gwasanaethau e-bost a cheisiwch eto, neu cysylltwch â'ch gweinyddwr rhwydwaith.
+errorQueuedDeliveryFailed=Digwyddodd gwall wrth anfon negeseuon heb eu hanfon.
+sendFailed=Methwyd anfon neges.
+
+## LOCALIZATION NOTE (sendFailedUnexpected): argument %X is a hex error code value
+sendFailedUnexpected=Wedi methu oherwydd gwall annisgwyl %X. Nid oes disgrifiad ar gael.
+
+## LOCALIZATION NOTE (smtpSecurityIssue): argument %S is the Outgoing server (SMTP) response
+smtpSecurityIssue=Rhaid cywiro'r ffurfweddiad sy'n gysylltiedig â %S.
+
+## LOCALIZATION NOTE (smtpServerError): argument %s is the Outgoing server (SMTP) response
+smtpServerError=Digwyddodd gwall wrth anfon e-bost: Gwall gweinydd Anfon (SMTP). Ymateb y gweinydd oedd:  %s.
+unableToSendLater=Ymddiheuriadau, nid oedd modd cadw eich neges i'w hanfon yn hwyrach.
+
+## LOCALIZATION NOTE (communicationsError): argument %d is the error code
+communicationsError=Digwyddodd gwall cyfathrebu: %d.  Ceisiwch eto.
+dontShowAlert=THIS IS JUST A PLACEHOLDER.  YOU SHOULD NEVER SEE THIS STRING.
+
+couldNotGetUsersMailAddress2=Digwyddodd gwall wrth anfon e-bost: roedd cyfeiriad anfon yr e-bost yn annilys. Gwiriwch fod y cyfeiriad e-bost yn gywir a cheisiwch eto.
+couldNotGetSendersIdentity=Digwyddodd gwall wrth anfon e-bost: roedd hunaniaeth yr anfonwr yn annilys. Gwiriwch ffurfweddiad eich hunaniaeth a cheisiwch eto.
+
+mimeMpartAttachmentError=Gwall atodi.
+failedCopyOperation=Anfonwyd y neges yn llwyddiannus, ond nid oedd modd ei chopïo i'ch ffolder Anfon.
+nntpNoCrossPosting=Dim ond un neges mae modd anfon i un gweinydd newyddion ar y tro.
+msgCancelling=Diddymu…
+sendFailedButNntpOk=Mae eich neges wedi ei chofnodi at y grŵp newyddion ond nid yw wedi'i hanfon at dderbynnydd arall.
+errorReadingFile=Gwall darllen ffeil.
+followupToSenderMessage=Mae awdur y neges yn gofyn bod ymateb yn cael ei yrru at yr awdur yn unig. Os hoffech chi ymateb i'r grŵp newyddion, ychwanegwch res arall i'r maes cyfeiriad, dewis Grŵp Newyddion o'r rhestr derbynwyr a rhoi enw'r grŵp newyddion.
+
+## LOCALIZATION NOTE (errorAttachingFile): argument %S is the file name/URI of the object to be attached
+errorAttachingFile=Ddigwyddodd gwall wrth atodi %S. Gwiriwch fod gennych fynediad i'r ffeil.
+
+## LOCALIZATION NOTE (incorrectSmtpGreeting): argument %s is the Outgoing server (SMTP) greeting
+incorrectSmtpGreeting=Gwall wrth anfon e-bost: Anfonodd y gweinydd e-bost gyfarchiad anghywir:  %s.
+
+## LOCALIZATION NOTE (errorSendingRcptCommand): argument %1$S is the Outgoing server (SMTP) response, argument %2$S is the intended message recipient.
+errorSendingRcptCommand=Digwyddodd gwall wrth anfon e-bost. Ymateb y gweinydd e-bost oedd:  \n%1$S.\n Gwiriwch fod y derbynnydd neges "%2$S" yn gywir a cheisiwch eto.
+
+## LOCALIZATION NOTE (startTlsFailed): argument %S is the Outgoing server (SMTP)
+startTlsFailed=Gwall wrth anfon e-bost: Methu sefydlu cysylltiad diogel gyda gweinydd Anfon (SMTP) %S drwy STARTTLS am nad yw'n hysbysu'r nodwedd hwnnw. Diffoddwch STARTTLS ar gyfer y gweinydd hwnnw neu cysylltwch â'ch darparwr gwasanaeth.
+
+## LOCALIZATION NOTE (smtpPasswordUndefined): argument %S is the Outgoing server (SMTP) account
+smtpPasswordUndefined=Digwyddodd gwall wrth anfon negeseuon: Methu derbyn cyfrinair %S. Heb anfon y neges.
+
+## LOCALIZATION NOTE (smtpSendNotAllowed): argument %s is the Outgoing server (SMTP) response
+smtpSendNotAllowed=Digwyddodd gwall wrth anfon e-bost. Ymateb y gweinydd e-bost yw:\n %s.\nDylech sicrhau eich bod yn defnyddio'r hunaniaeth gywir i'w hanfon a bod y dull dilysu a ddefnyddir yn gywir. Gwiriwch eich bod yn gallu anfon eich tystysgrifau cyfredol o'r rhwydwaith presennol drwy'r gweinydd SMTP hwn.
+
+## LOCALIZATION NOTE (smtpTempSizeExceeded): argument %s is the Outgoing server (SMTP) response
+smtpTempSizeExceeded=Mae maint y neges rydych yn ceisio ei anfon yn fwy nag uchafswm dros dro'r gweinydd. Nid yw'r neges wedi'i hanfon; ceisiwch leihau maint y neges neu aros peth amser a cheisio eto. Ymateb y gweinydd:  %s.
+
+## LOCALIZATION NOTE (smtpClientid): argument %s is the Outgoing server (SMTP) response
+smtpClientid=Mae'r gweinydd allan (SMTP) wedi canfod gwall yn y gorchymyn CLIENTID. Nid yw'r neges wedi ei hanjfon. Ymateb y gweinydd yw: %s
+
+## LOCALIZATION NOTE (smtpClientidPermission): argument %s is the Outgoing server (SMTP) response
+smtpClientidPermission=Mae ymateb y gweinydd allan (SMTP) i'r gorchymyn CLIENTID yn awgrymu nad yw eich dyfais yn cael anfon e-byst. Ymateb y gweinydd yw: %s
+
+## LOCALIZATION NOTE (smtpPermSizeExceeded1): argument %d is the Outgoing server (SMTP) size limit
+smtpPermSizeExceeded1=Mae maint y neges rydych yn ceisio ei hanfon yn fwy nag uchafswm eang dros dro'r gweinydd (%d beit). Nid yw'r neges wedi'i hanfon; ceisiwch leihau maint y neges neu aros peth amser a cheisio eto.
+
+## LOCALIZATION NOTE (smtpPermSizeExceeded2): argument %s is the Outgoing server (SMTP) response
+smtpPermSizeExceeded2=Mae maint y neges rydych yn ceisio ei hanfon yn fwy nag uchafswm eang dros dro'r gweinydd. Nid yw'r neges wedi'i hanfon; ceisiwch leihau maint y neges neu aros peth amser a cheisio eto. Ymateb y gweinydd:  %s.
+
+## LOCALIZATION NOTE (smtpSendFailedUnknownServer): argument %S is the Outgoing server (SMTP)
+smtpSendFailedUnknownServer=Digwyddodd gwall wrth anfon e-bost: Mae'r gweinydd Anfon (SMTP) %S yn anhysbys. Efallai fod y gweinydd wedi'i ffurfweddu yn anghywir. Gwiriwch gosodiadau eich gweinydd (SMTP) yn gywir a cheisiwch eto.
+
+## LOCALIZATION NOTE (smtpSendRequestRefused): argument %S is the Outgoing server (SMTP)
+smtpSendRequestRefused=Nid oedd modd anfon y neges gan fod cysylltu â'r gweinydd Anfon (SMTP) %S wedi methu. Gall fod nad yw'r gweinydd ar gael neu'n gwrthod cysylltiadau SMTP. Gwiriwch fod gosodiadau eich gweinydd Allan (SMTP) yn gywir a cheisiwch eto.
+
+## LOCALIZATION NOTE (smtpSendInterrupted): argument %S is the Outgoing server (SMTP)
+smtpSendInterrupted=Nid oedd modd anfon y neges gan fod cysylltiad â'r gweinydd Anfon (SMTP) %S wedi ei golli yng nghanol trosglwyddiad. Ceisiwch eto.
+
+## LOCALIZATION NOTE (smtpSendTimeout): argument %S is the Outgoing server (SMTP)
+smtpSendTimeout=Nid oedd modd anfon y neges gan fod cysylltu â'r gweinydd Anfon (SMTP) %S wedi dod i ben. Ceisiwch eto.
+
+## LOCALIZATION NOTE (smtpSendFailedUnknownReason): argument %S is the Outgoing server (SMTP)
+smtpSendFailedUnknownReason=Nid oedd modd anfon y neges gan fod cysylltu â'r gweinydd Anfon (SMTP) %S am reswm anhysbys. Gwiriwch fod gosodiadau gweinydd Allan (SMTP) yn gywir a cheisiwch eto.
+
+# LOCALIZATION NOTE (smtpHintAuthEncryptToPlainNoSsl): %S is the server hostname
+smtpHintAuthEncryptToPlainNoSsl=Nid yw'r gweinydd Anfon (SMTP) %S i weld yn cynnal cyfrineiriau wedi eu hamgryptio. Os ydych newydd greu'r cyfrif, ceisiwch newydd y 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gosodiadau gweinydd (SMTP)' i 'Cyfrinair, trosglwyddo anniogel'. Os oedd arfer gweithio ond nid yw nawr, gallwch fod yn agored i gael eich cyfrinair wedi ei ddwyn.
+
+# LOCALIZATION NOTE (smtpHintAuthEncryptToPlainSsl): %S is the server hostname
+smtpHintAuthEncryptToPlainSsl=Nid yw'r gweinydd Anfon (SMTP) %S i weld yn cynnal cyfrineiriau wedi eu hamgryptio. Os ydych newydd greu'r cyfrif, ceisiwch newydd y 'dull Dilysu' yn 'Gosodiadau Cyfrif | Gweinydd anfon (SMTP)' i 'Cyfrinair arferol'.
+
+# LOCALIZATION NOTE (smtpHintAuthPlainToEncrypt): %S is the server hostname
+smtpHintAuthPlainToEncrypt=Nid yw'r gweinydd Anfon (SMTP) %S yn caniatáu cyfrineiriau testun plaen. Ceisiwch newydd y 'dull Dilysu' yn 'Gosodiadau Cyfrif | Gweinydd anfon (SMTP)' i 'Cyfrinair amgryptiedig'.
+
+# LOCALIZATION NOTE (smtpAuthFailure): %S is the server hostname
+smtpAuthFailure=Methu dilysu gweinydd Anfon (SMTP) %S. Gwiriwch eich cyfrinair a dilysu eich 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gweinydd anfon' (SMTP)'.
+
+# LOCALIZATION NOTE (smtpAuthGssapi): %S is the server hostname
+smtpAuthGssapi=Nid yw'r tocyn Kerberos/GSSAPI ticket wedi'i dderbyn gan weinydd Anfon (SMTP) %S. Gwiriwch eich bod wedi eich mewngofnodi i gylch Kerberos/GSSAPI.
+
+# LOCALIZATION NOTE (smtpAuthMechNotSupported): %S is the server hostname
+smtpAuthMechNotSupported=Nid yw'r gweinydd Anfon (SMTP) %S yn cynnal y dull yma o ddilysu. Ceisiwch newid y 'Dull dilysu' yn 'Gosodiadau Cyfrif | Gweinydd Anfon (SMTP)'.
+
+# LOCALIZATION NOTE (errorIllegalLocalPart2): %s is an email address with an illegal localpart
+errorIllegalLocalPart2=Mae nodau nad ydynt yn ASCII yn rhan leol cyfeiriad y derbynnydd %s ac nid yw'ch gweinydd yn cefnogi SMTPUTF8. Newidiwch y cyfeiriad hwn a rhowch gynnig arall arni.
+
+## Strings used for the save message dialog shown when the user closes a message compose window
+saveDlogTitle=Cadw Neges
+
+## LOCALIZATION NOTE (saveDlogMessages3): Do not translate the words %1$S and \n.
+## %1$S is replaced by the folder name configured for saving drafts (typically the "Drafts" folder).
+## Translate "Write" to match the translation of item "windowTitleWrite" below.
+saveDlogMessages3=Cadw'r neges hon yn eich ffolder drafftiau (%1$S) a chau'r ffenestr Ysgrifennu?
+discardButtonLabel=&Dileu newidiadau
+
+## generics string
+defaultSubject=(dim pwnc)
+chooseFileToAttach=Atodi Ffeil(iau)
+genericFailureExplanation=Gwiriwch osodiadau eich cyfrif a rhowch gynnig arall arni.
+
+## LOCALIZATION NOTE (undisclosedRecipients): this string must use only US_ASCII characters
+undisclosedRecipients=derbynnydd cudd
+
+# LOCALIZATION NOTE (chooseFileToAttachViaCloud): %1$S is the cloud
+# provider to save the file to.
+chooseFileToAttachViaCloud=Atodi Ffeil(iau) drwy %1$S
+
+## Window titles
+# LOCALIZATION NOTE (windowTitleWrite):
+# %1$S is the message subject.
+# %2$S is the application name.
+# Example: Write: Re: Invitation - Thunderbird
+windowTitleWrite=Ysgrifennu: %1$S - %2$S
+# LOCALIZATION NOTE (windowTitlePrintPreview):
+# %1$S is the message subject.
+# %2$S is the application name.
+# Example: Print Preview: Re: Invitation - Thunderbird
+windowTitlePrintPreview=Rhagolwg Argraffu: %1$S - %2$S
+
+## From field
+msgIdentityPlaceholder=Rhowch gyfeiriad Oddi Wrth cyfaddas i'w ddefnyddio y lle %S
+customizeFromAddressTitle=Cyfaddasu Cyfeiriad Oddi Wrth
+customizeFromAddressWarning=Os yw eich darparwr e-byst yn ei gynnal, mae Cyfaddasu Cyfeiriad Oddi Wrth yn caniatáu i chi wneud mân newidiadau dros dro heb bod angen creu hunaniaeth newydd yn Ngosodiadau'r Cyfrif. Er enghraifft, os yw eich cyfeiriad Oddi wrth yn John Doe <john@example.com> efallai yr hoffech ei newid i John Doe <john+doe@example.com> neu John <john@example.com>.
+customizeFromAddressIgnore=Peidio fy hysbysu am hyn eto
+
+## Strings used by the empty subject dialog
+subjectEmptyTitle=Atgoffwr Pwnc
+subjectEmptyMessage=Nid oes gan eich neges bwnc.
+sendWithEmptySubjectButton=&Anfon Heb Bwnc
+cancelSendingButton=&Diddymu Anfon
+
+## Strings used by the dialog that informs about the lack of newsgroup support.
+noNewsgroupSupportTitle=Nid yw Grwpiau Newyddion yn Cael eu Cynnal
+recipientDlogMessage=Dim ond derbynwyr e-bost mae'r cyfrif yma yn ei gynnal. Bydd parhau yn anwybyddu grwpiau newyddion.
+
+## Strings used by the alert that tells the user that an email address is invalid.
+addressInvalidTitle=Cyfeiriad Derbynnydd Annilys
+addressInvalid=Nid yw %1$S yn gyfeiriad e-bost dilys gan nad yw yn ffurf user@host. Rhaid cywiro hyn cyn anfon yr e-bost.
+
+## String used by the dialog that asks the user to attach a web page
+attachPageDlogTitle=Nodwch leoliad i'w atodi
+attachPageDlogMessage=Tudalen Gwe (URL):
+
+## String used for attachment pretty name, when the attachment is a message
+messageAttachmentSafeName=Neges wedi'i Hatodi
+
+## String used for attachment pretty name, when the attachment is a message part
+partAttachmentSafeName=Rhan o Neges wedi'i Hatodi
+
+# LOCALIZATION NOTE (attachmentBucketAttachFilesTooltip):
+# This tooltip should be same as attachFile.label in messengercompose.dtd,
+# but without ellipsis (…).
+attachmentBucketAttachFilesTooltip=Atodi Ffeil(iau)
+attachmentBucketClearSelectionTooltip=Clirio'r Dewis
+attachmentBucketHeaderShowTooltip=Dangos paen atodiad
+attachmentBucketHeaderMinimizeTooltip=Lleihau'r paen atodiad
+attachmentBucketHeaderRestoreTooltip=Adfer y paen atodiad
+
+## String used by the Initialization Error dialog
+initErrorDlogTitle=Ysgrifennu Neges
+initErrorDlgMessage=Digwyddodd gwall wrth greu ffenestr ysgrifennu neges. Ceisiwch eto.
+
+## String used if a file to attach does not exist when passed as
+## a command line argument
+errorFileAttachTitle=Atodi Ffeil
+
+## LOCALIZATION NOTE (errorFileAttachMessage): %1$S will be replaced by the non-existent file name.
+errorFileAttachMessage=Nid yw ffeil %1$S yn bodoli felly nid oedd modd ei hatodi i'r neges.
+
+## String used if a file to serve as message body does not exist or cannot be loaded when passed
+## as a command line argument
+errorFileMessageTitle=Ffeil Neges
+
+## LOCALIZATION NOTE (errorFileMessageMessage): %1$S will be replaced by the non-existent file name.
+errorFileMessageMessage=Nid yw ffeil %1$S yn bodoli ac nid oedd modd ei defnyddio fel corff neges.
+
+## LOCALIZATION NOTE (errorLoadFileMessageMessage): %1$S will be replaced by the name of the file that can't be loaded.
+errorLoadFileMessageMessage=Nid oedd modd llwytho %1$S fel corff neges.
+
+## Strings used by the Save as Draft/Template dialog
+SaveDialogTitle=Cadw Neges
+
+## LOCALIZATION NOTE (SaveDialogMsg): %1$S is the folder name, %2$S is the host name
+SaveDialogMsg=Mae eich neges wedi'i chadw i ffolder %1$S o dan %2$S.
+CheckMsg=Peidiwch â dangos y blwch deialog hwn i mi eto.
+
+## Strings used by the prompt when Quitting while in progress
+quitComposeWindowTitle=Anfon Neges
+
+## LOCALIZATION NOTE (quitComposeWindowMessage2): don't translate \n
+quitComposeWindowMessage2=Mae %1$S wrthi'n anfon neges.\nHoffech chi aros tan fod y neges wedi ei hanfon cyn gadael neu gadael nawr?
+quitComposeWindowQuitButtonLabel2=&Gadael
+quitComposeWindowWaitButtonLabel2=&Aros
+quitComposeWindowSaveTitle=Cadw Neges
+
+## LOCALIZATION NOTE (quitComposeWindowSaveMessage): don't translate \n
+quitComposeWindowSaveMessage=Mae %1$S wrthi'n cadw neges.\nHoffech chi aros tan fod y neges wedi ei chadw cyn gadael neu gadael nawr?
+
+## Strings used by the prompt for Ctrl-Enter check before sending message
+sendMessageCheckWindowTitle=Anfon Neges
+sendMessageCheckLabel=Ydych chi'n siŵr eich bod yn barod i anfon y neges hon?
+sendMessageCheckSendButtonLabel=Anfon
+assemblingMessageDone=Cydosod neges...Wedi gorffen
+assemblingMessage=Cydosod neges…
+smtpDeliveringMail=Anfon e-bost…
+smtpMailSent=E-bost wedi'i anfon yn llwyddiannus
+assemblingMailInformation=Crynhoi gwybodaeth e-bost…
+
+## LOCALIZATION NOTE (gatheringAttachment): argument %S is the file name/URI of attachment
+gatheringAttachment=Atodi %S…
+creatingMailMessage=Creu neges e-bost…
+
+## LOCALIZATION NOTE (copyMessageStart): argument %S is the folder name
+copyMessageStart=Copïo neges i'r ffolder %S…
+copyMessageComplete=Copïo wedi gorffen.
+copyMessageFailed=Methodd copïo.
+filterMessageComplete=Mae'r hidl wedi ei gwblhau.
+filterMessageFailed=Methodd yr hidl.
+
+## LOCALIZATION NOTE (largeMessageSendWarning):
+## Do not translate %S. It is the size of the message in user-friendly notation.
+largeMessageSendWarning=Rhybudd! Rydych ar fin anfon neges o faint %S. Ydych chi'n siŵr eich bod eisiau gwneud hyn?
+sendingMessage=Anfon neges…
+sendMessageErrorTitle=Anfon Neges Gwall
+postingMessage=Cofnodi neges…
+sendLaterErrorTitle=Anfon Gwall Diweddarach
+saveDraftErrorTitle=Cadw Gwall Drafft
+saveTemplateErrorTitle=Cadw Gwall Templed
+
+## LOCALIZATION NOTE (failureOnObjectEmbeddingWhileSaving): argument %.200S is the file name/URI of object to be embedded
+failureOnObjectEmbeddingWhileSaving=Bu anhawster wrth gynnwys neges %.200S yn y neges. Hoffech chi barhau i gadw'r ffeil heb y neges?
+
+## LOCALIZATION NOTE (failureOnObjectEmbeddingWhileSending): argument %.200S is the file name/URI of object to be embedded
+failureOnObjectEmbeddingWhileSending=Bu anhawster wrth gynnwys y ffeil %.200S yn y neges. Hoffech chi barhau i anfon y neges heb y ffeil?
+returnToComposeWindowQuestion=Hoffech chi ddychwelyd i'r ffenestr ysgrifennu?
+
+## reply header in composeMsg
+## LOCALIZATION NOTE (mailnews.reply_header_authorwrotesingle): #1 is the author (name of the person replying to)
+mailnews.reply_header_authorwrotesingle=Ysgrifennodd #1:
+
+## LOCALIZATION NOTE (mailnews.reply_header_ondateauthorwrote): #1 is the author, #2 is the date, #3 is the time
+mailnews.reply_header_ondateauthorwrote=Ar #2 #3, ysgrifennodd #1:
+
+## LOCALIZATION NOTE (mailnews.reply_header_authorwroteondate): #1 is the author, #2 is the date, #3 is the time
+mailnews.reply_header_authorwroteondate=Ysgrifennodd #1 ar #2 #3:
+
+## reply header in composeMsg
+## user specified
+mailnews.reply_header_originalmessage=-------- Neges Wreiddiol --------
+
+## forwarded header in composeMsg
+## user specified
+mailnews.forward_header_originalmessage=-------- Neges Wreiddiol --------
+
+## Strings used by the rename attachment dialog
+renameAttachmentTitle=Ailenwi Atodiad
+renameAttachmentMessage=Enw newydd yr atodiad:
+
+## Attachment Reminder
+## LOCALIZATION NOTE (mail.compose.attachment_reminder_keywords): comma separated
+## words that should trigger an attachment reminder.
+mail.compose.attachment_reminder_keywords=.doc,.pdf,.xls,.ppt,.rtf,.pps,atodiad,attachment,atodi,attach,attached,attaching,amgaeëdig, enclosed,CV,llythyr,cover letter
+
+remindLaterButton=Atgoffa Fi yn Ddiweddarach
+remindLaterButton.accesskey=D
+disableAttachmentReminderButton=Analluogwch atgoffwr atodiad ar gyfer y neges hon
+attachmentReminderTitle=Atgoffa am Atodiad
+attachmentReminderMsg=Ydych chi wedi anghofio atodi atodiad?
+
+# LOCALIZATION NOTE (attachmentReminderKeywordsMsgs): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# #1 number of keywords
+attachmentReminderKeywordsMsgs=Wedi canfod dim allweddeiriau atodiadau:;Wedi canfod #1 allweddair atodiad:;Wedi canfod #1 allweddair atodiad:;Wedi canfod #1 allweddair atodiad:;Wedi canfod #1 allweddair atodiad:;Wedi canfod #1 allweddair atodiad:
+attachmentReminderOptionsMsg=Mae modd ffurfweddi geiriau ar gyfer atodiadau yn eich dewisiadau
+attachmentReminderYesIForgot=O, do!
+attachmentReminderFalseAlarm=Na, Anfon Nawr
+
+# Strings used by the Filelink offer notification bar.
+learnMore.label=Dysgu Rhagor…
+learnMore.accesskey=D
+
+# LOCALIZATION NOTE (bigFileDescription): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# #1 number of big attached files
+bigFileDescription=Dim ffeiliau.;Mae'r ffeiliau hyn yn fawr iawn. Efallai y byddai'n well defnyddio Filelink.;Mae'r ffeiliau hyn yn fawr iawn. Efallai y byddai'n well defnyddio Filelink.;Mae'r ffeiliau hyn yn fawr iawn. Efallai y byddai'n well defnyddio Filelink.;Mae'r ffeiliau hyn yn fawr iawn. Efallai y byddai'n well defnyddio Filelink.;Mae'r ffeiliau hyn yn fawr iawn. Efallai y byddai'n well defnyddio Filelink.
+bigFileShare.label=Dolen
+bigFileShare.accesskey=D
+bigFileAttach.label=Anwybyddu
+bigFileAttach.accesskey=A
+bigFileChooseAccount.title=Dewis Cyfrif
+bigFileChooseAccount.text=Dewis cyfrif cwmwl i lwytho'r atodiad iddo
+bigFileHideNotification.title=Peidio Llwytho fy Ffeiliau i Fyny
+bigFileHideNotification.text=Ni fyddwch yn cael eich hysbysu os byddwch yn atodi rhagor o ffeiliau mawr i'r neges hon.
+bigFileHideNotification.check=Peidio fy hysbysu am hyn eto.
+
+# LOCALIZATION NOTE(cloudFileUploadingTooltip): Do not translate the string
+# %S. %S is the display name for the cloud account the attachment is being
+# uploaded to.
+cloudFileUploadingTooltip=Llwytho i fyny i %S…
+
+# LOCALIZATION NOTE(cloudFileUploadedTooltip): Do not translate the string
+# %S. %S is the display name for the cloud account the attachment was uploaded
+# to.
+cloudFileUploadedTooltip=Wedi'u llwytho i fyny i %S
+cloudFileUploadingNotification=Mae eich ffeil wedi'i chysylltu. Bydd yn ymddangos yng nghorff y neges ar ôl ei gwblhau.;Mae eich ffeiliau wedi'u cysylltu. Byddant yn ymddangos yng nghorff y neges ar ôl ei gwblhau.
+cloudFileUploadingCancel.label=Diddymu
+cloudFileUploadingCancel.accesskey=D
+cloudFilePrivacyNotification=Mae cysylltu wedi ei gwblhau. Sylwch y gall atodiadau sydd wedi eu cysylltu fod yn agored i bobl all weld neu ddyfalu'r dolenni.
+
+## LOCALIZATION NOTE(smtpEnterPasswordPrompt): Do not translate the
+## word %S. Place the word %S where the host name should appear.
+smtpEnterPasswordPrompt=Rhowch eich cyfrinair ar gyfer %S:
+
+## LOCALIZATION NOTE(smtpEnterPasswordPromptWithUsername): Do not translate the
+## words %1$S and %2$S. Place the word %1$S where the host name should appear,
+## and %2$S where the user name should appear.
+smtpEnterPasswordPromptWithUsername=Rhowch eich cyfrinair ar gyfer %2$S ar %1$S:
+## LOCALIZATION NOTE(smtpEnterPasswordPromptTitleWithHostname): Do not translate the
+## word %1$S. Place the word %1$S where the server host name should appear.
+smtpEnterPasswordPromptTitleWithHostname=Mae Angen Cyfrinair ar gyfer Gweinydd Allanol (SMTP) %1$S
+
+# LOCALIZATION NOTE (removeAttachmentMsgs): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+removeAttachmentMsgs=Dim Atodiadau;Tynnu Atodiad;Tynnu Atodiadau;Tynnu Atodiadau;Tynnu Atodiadau;Tynnu Atodiadau
+
+## LOCALIZATION NOTE(promptToSaveSentLocally2): Do not translate the strings %1$S, %2$S, %3$S and \n.
+## %2$S will be replaced with the account name. $1$S will be replaced by the folder name
+## configured to contain saved sent messages (typically the "Sent" folder).
+## %3$S will be replaced with the local folders account name (typically "Local Folders").
+## Translate "Write" to match the translation of item "windowTitleWrite" above.
+promptToSaveSentLocally2=Anfonwyd eich neges ond nid oes copi wedi ei gosod yn eich ffolder anfon (%1$S) oherwydd gwallau rhwydwaith neu fynediad i ffeil.\nGallwch geisio eto neu gadw'r neges yn lleol i %3$S/%1$S-%2$S.
+errorFilteringMsg=Mae eich neges wedi ei hanfon a'i chadw, ond bu gwall wrth redeg yr hidlau neges arni.
+errorCloudFileAuth.title=Gwall Dilysu
+
+## LOCALIZATION NOTE(promptToSaveDraftLocally2): Do not translate the strings %1$S, %2$S, %3$S and \n.
+## %2$S will be replaced with the account name. $1$S will be replaced by the folder name
+## configured to contain saved draft messages (typically the "Drafts" folder).
+## %3$S will be replaced with the local folders account name (typically "Local Folders").
+promptToSaveDraftLocally2=Nid yw eich neges ddrafft wedi ei chopïo i'ch ffolder drafft (%1$S) oherwydd gwallau rhwydwaith neu fynediad i ffeil.\nGallwch geisio eto neu gadw'r neges yn lleol i %3$S/%1$S-%2$S.
+buttonLabelRetry2=&Ceisio eto
+
+## LOCALIZATION NOTE(promptToSaveTemplateLocally2): Do not translate the strings %1$S, %2$S, %3$S and \n.
+## %2$S will be replaced with the account name. $1$S will be replaced by the folder name
+## configured to contain saved templates (typically the "Templates" folder).
+## %3$S will be replaced with the local folders account name (typically "Local Folders").
+promptToSaveTemplateLocally2=Nid yw eich templed wedi ei gopïo i'ch ffolder templedi (%1$S) oherwydd gwallau rhwydwaith neu fynediad i ffeil.\nGallwch geisio eto neu gadw'r neges yn lleol i %3$S/%1$S-%2$S.
+
+## LOCALIZATION NOTE(saveToLocalFoldersFailed): Message appears after normal
+## save fails (e.g., to Sent) and save to Local Folders also fails. This could
+## occur if network is down and filesystem problems are present such as disk
+## full, permission issues or hardware failure.
+saveToLocalFoldersFailed=Methu cadw eich neges i ffolderi lleol. Posib nad oes lle storio yn weddill.
+
+## LOCALIZATION NOTE(errorCloudFileAuth.message):
+## %1$S is the name of the online storage service against which the authentication failed.
+errorCloudFileAuth.message=Methu dilysu i %1$S.
+errorCloudFileUpload.title=Gwall Llwytho i Fyny
+
+## LOCALIZATION NOTE(errorCloudFileUpload.message):
+## %1$S is the name of the online storage service against which the uploading failed.
+## %2$S is the name of the file that failed to upload.
+errorCloudFileUpload.message=Methu llwytho %2$S i fyny i %1$S.
+errorCloudFileQuota.title=Gwall Cwota
+
+## LOCALIZATION NOTE(errorCloudFileQuota.message):
+## %1$S is the name of the online storage service being uploaded to.
+## %2$S is the name of the file that could not be uploaded due to exceeding the storage limit.
+errorCloudFileQuota.message=Bydd llwytho %2$S i fyny i %1$S yn croesi trothwy eich cwota.
+errorCloudFileLimit.title=Gwall Maint Ffeil
+
+## LOCALIZATION NOTE(errorCloudFileLimit.message):
+## %1$S is the name of the online storage service being uploaded to.
+## %2$S is the name of the file that could not be uploaded due to size restrictions.
+errorCloudFileLimit.message=Mae %2$S yn fwy na maint mwyaf %1$S.
+errorCloudFileOther.title=Gwall Anhysbys
+
+## LOCALIZATION NOTE(errorCloudFileOther.message):
+## %1$S is the name of the online storage service that cannot be communicated with.
+errorCloudFileOther.message=Digwyddodd gwall anhysbys wrth gyfathrebu gyda %1$S.
+errorCloudFileDeletion.title=Gwall Dileu
+
+## LOCALIZATION NOTE(errorCloudFileDeletion.message):
+## %1$S is the name of the online storage service that the file is to be deleted from.
+## %2$S is the name of the file that failed to be deleted.
+errorCloudFileDeletion.message=Nid oedd anhawster wrth ddileu %2$S o %1$S.
+errorCloudFileUpgrade.label=Diweddaru
+
+## LOCALIZATION NOTE(stopShowingUploadingNotification): This string is used in the Filelink
+## upload notification bar to allow the user to dismiss the notification permanently.
+stopShowingUploadingNotification.accesskey=P
+stopShowingUploadingNotification.label=Peidio dangos hwn eto
+replaceButton.label=Amnewid…
+replaceButton.accesskey=a
+replaceButton.tooltip=Dangos y deialog Canfod ac Newid
+
+## LOCALIZATION NOTE(blockedAllowResource): %S is the URL to load.
+blockedAllowResource=Dadrwystro %S
+## LOCALIZATION NOTE (blockedContentMessage): Semi-colon list of plural forms.
+## See: https://developer.mozilla.org/en/docs/Localization_and_Plurals
+## %S will be replaced by brandShortName.
+## Files must be unblocked individually, therefore the plural form reads:
+## Unblocking a file (one of several) will include it (that one file) in your sent message.
+## In other words:
+## Unblocking one/several file(s) will include it/them in your message.
+blockedContentMessage=Nid yw %S wedi rhwystro ffeiliau rhag llwytho i'r neges hon. Bydd dad-rwystro'r ffeil yn ei chynnwys yn eich neges a anfonwyd;Mae %S wedi rhwystro ffeiliau rhag llwytho i'r neges hon. Bydd dad-rwystro'r ffeil yn ei chynnwys yn eich neges a anfonwyd.;Mae %S wedi rhwystro ffeiliau rhag llwytho i'r neges hon. Bydd dad-rwystro'r ffeil yn ei chynnwys yn eich neges a anfonwyd.;Mae %S wedi rhwystro ffeiliau rhag llwytho i'r neges hon. Bydd dad-rwystro'r ffeil yn ei chynnwys yn eich neges a anfonwyd.;Mae %S wedi rhwystro ffeiliau rhag llwytho i'r neges hon. Bydd dad-rwystro'r ffeil yn ei chynnwys yn eich neges a anfonwyd.;Mae %S wedi rhwystro ffeiliau rhag llwytho i'r neges hon. Bydd dad-rwystro'r ffeil yn ei chynnwys yn eich neges a anfonwyd.
+
+blockedContentPrefLabel=Dewisiadau
+blockedContentPrefAccesskey=D
+
+blockedContentPrefLabelUnix=Dewisiadau
+blockedContentPrefAccesskeyUnix=e
+
+## Recipient pills fields.
+## LOCALIZATION NOTE(confirmRemoveRecipientRowTitle2): %S will be replaced with the field name.
+confirmRemoveRecipientRowTitle2=Tynnwch Gyfeiriadau %S
+## LOCALIZATION NOTE(confirmRemoveRecipientRowBody2): %S will be replaced with the field name.
+confirmRemoveRecipientRowBody2=Ydych chi'n siŵr eich bod am gael gwared ar gyfeiriadau %S?
+confirmRemoveRecipientRowButton=Tynnu
+
+## LOCALIZATION NOTE headersSpaceStyle is for aligning label of a newly create recipient row.
+## It should be larger than the largest Header label and identical to &headersSpace2.style;
+headersSpaceStyle=width: 8em
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/editor.properties b/l10n-cy/mail/chrome/messenger/messengercompose/editor.properties
new file mode 100644
index 0000000000..62a5d47d26
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/editor.properties
@@ -0,0 +1,208 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE FILE: embedded "\n" represent HTML breaks (<br>)
+# Don't translate embedded "\n".
+# Don't translate strings like this: %variable% 
+#  as they will be replaced using JavaScript
+#
+No=Na
+Save=Cadw
+More=Rhagor
+Less=Llai
+MoreProperties=Rhagor o Briodweddau
+FewerProperties=Llai o Briodweddau
+PropertiesAccessKey=P
+None=Dim
+none=dim
+OpenHTMLFile=Agor Ffeil HTML
+OpenTextFile=Agor Ffeil Testun
+SelectImageFile=Dewiswch Ffeil Delwedd
+SaveDocument=Cadw Tudalen
+SaveDocumentAs=Cadw Tudalen Fel
+SaveTextAs=Cadw Testun Fel
+EditMode=Modd Golygu
+Preview=Rhagolwg
+Publish=Cyhoeddi
+PublishPage=Cyhoeddi Tudalen
+DontPublish=Peidio Cyhoeddi
+SavePassword=Defnyddiwch y Rheolwr Cyfrinair i gadw'r cyfrinair
+CorrectSpelling=(sillafu cywir)
+NoSuggestedWords=(dim geiriau'n cael eu cynnig)
+NoMisspelledWord=Does dim geiriau wedi'u camsillafu
+CheckSpellingDone=Cwblhawyd gwirio'r sillafu.
+CheckSpelling=Gwirio Sillafu
+InputError=Gwall
+Alert=Rhybudd
+CantEditFramesetMsg=Nid yw'r golygydd yn gallu golygu fframsetiau HTML na thudalennau gyda fframiau mewnlin. Ar gyfer fframsetiau ceisiwch olygu'r dudalen ar gyfer pob ffrâm ar wahân. Am dudalennau gyda fframiau, cadwch gopi o'r dudalen a thynnu'r tag <iframe>.
+CantEditMimeTypeMsg=Does dim modd golygu'r math yma o dudalen.
+CantEditDocumentMsg=Does dim modd golygu'r dudalen am reswm anhysbys.
+BeforeClosing=cyn cau
+BeforePreview=cyn edrych arno yn y porwr
+BeforeValidate=cyn gwirio'r ddogfen
+# LOCALIZATION NOTE (SaveFilePrompt, PublishPrompt): Don't translate %title% and %reason% (this is the reason for asking user to close, such as "before closing")
+SaveFilePrompt=Cadw newidiadau i "%title%" %reason%?\u0020
+PublishPrompt=Cadw newidiadau i "%title%" %reason%?\u0020
+SaveFileFailed=Methwyd cadw'r ffeil!
+
+# Publishing error strings:
+# LOCALIZATION NOTE Don't translate %dir% or %file% in the Publishing error strings:
+FileNotFound=Heb ganfod %file%.
+SubdirDoesNotExist=Nid yw'r is-gyfeiriadur "%dir%" yn bodoli ar y safle hwn neu mae'r enw ffeil "%file%" yn cael ei ddefnyddio gan is-gyfeiriadur arall.
+FilenameIsSubdir=Mae'r enw ffeil "%file%" yn cael ei ddefnyddio eisoes gan is-gyfeiriadur arall.
+ServerNotAvailable=Nid yw'r gweinydd ar gael. Gwiriwch eich cysylltiad a cheisiwch eto yn ddiweddarach.
+Offline=Rydych all-lein. Cliciwch yr eicon wrth ymyl y gornel de gwaelod unrhyw ffenestr i fynd ar-lein.
+DiskFull=Does dim digon o le ar ddisg ar gael i gadw ffeil "%file%."
+NameTooLong=Mae'r enw ffeil neu is-gyfeiriadur yn rhy hir.
+AccessDenied=Does gennych ddim caniatâd i chi gyhoeddi i'r lleoliad hwn.
+UnknownPublishError=Digwyddodd gwall cyhoeddi anhysbys.
+PublishFailed=Methodd y cyhoeddi.
+PublishCompleted=Wedi cwblhau'r cyhoeddi.
+AllFilesPublished=Pob ffeil eu cyhoeddi
+# LOCALIZATION NOTE Don't translate %x% or %total%
+FailedFileMsg=Methodd %x% o %total% ffeil gael eu cyhoeddi.
+# End-Publishing error strings
+Prompt=Anogiad
+# LOCALIZATION NOTE (PromptFTPUsernamePassword): Don't translate %host% 
+PromptFTPUsernamePassword=Rhowch enw defnyddiwr a chyfrinair ar gyfer gweinydd FTP %host%
+RevertCaption=Dychwelyd i Cadwyd Diwethaf
+Revert=Dychwelyd
+SendPageReason=cyn anfon y dudalen
+Send=Anfon
+## LOCALIZATION NOTE (PublishProgressCaption, PublishToSite, AbandonChanges): Don't translate %title%
+PublishProgressCaption=Cyhoeddi: %title%
+PublishToSite=Cyhoeddi i Wefan: %title%
+AbandonChanges=Gadael newidiadau heb eu cadw i "%title%" ac ail-lwytho'r dudalen?
+DocumentTitle=Teitl y Dudalen
+NeedDocTitle=Rhoi teitl i'r dudalen gyfredol.
+DocTitleHelp=Mae hwn yn adnabod y dudalen yn nheitl y ffenestr a'r nodau tudalen.
+CancelPublishTitle=Diddymu'r cyhoeddi?
+## LOCALIZATION NOTE: "Continue" in this sentence must match the text for
+## the CancelPublishContinue key below
+CancelPublishMessage=Gall diddymu argraffu arwain at eich ffeil(iau)'n cael eu trosglwyddo'n wallus. Parhau neu Diddymu?
+CancelPublishContinue=Parhau
+MissingImageError=Rhoi neu ddewis ddelwedd gif, jpg, neu png.
+EmptyHREFError=Rhaid rhoi neu ddewis lleoliad i greu dolen newydd.
+LinkText=Cysylltu Testun
+LinkImage=Cysylltu Delwedd
+MixedSelection=[Dewis cymysg]
+Mixed=(cymysg)
+# LOCALIZATION NOTE (NotInstalled): %S is the name of the font
+NotInstalled=%S (heb ei osod)
+EnterLinkText=Rhoi testun i'w arddangos ar gyfer y ddolen:
+EnterLinkTextAccessKey=T
+EmptyLinkTextError=Rhowch ychydig o destun ar gyfer y ddolen.
+EditTextWarning=Bydd hwn yn cymryd lle'r cynnwys cyfredol.
+#LOCALIZATION NOTE (ValidateNumber):Don't translate: %n% %min% %max%
+ValidateRangeMsg=Mae'r rhif rydych wedi'i rhoi (%n%) tu allan i'r amrediad sy'n cael ei ganiatáu.
+ValidateNumberMsg=Rhowch rif rhwng %min% a %max%.
+MissingAnchorNameError=Rhowch enw i'r angor.
+#LOCALIZATION NOTE (DuplicateAnchorNameError): Don't translate %name%
+DuplicateAnchorNameError=Mae "%name%" yn bodoli eisoes ar y dudalen. Rhowch enw gwahanol.
+BulletStyle=Arddull Bwled
+SolidCircle=Cylch solet
+OpenCircle=Cylch agored
+SolidSquare=Sgwâr solet
+NumberStyle=Arddull Rhif
+Automatic=Awtomatig
+Style_1=1, 2, 3…
+Style_I=I, II, III…
+Style_i=i, ii, iii…
+Style_A=A, B, C…
+Style_a=a, b, c…
+Pixels=picseli
+Percent=y cant
+PercentOfCell=% o gell
+PercentOfWindow=% o ffenestr
+PercentOfTable=% o dabl
+#LOCALIZATION NOTE (untitledTitle): %S is the window #.  No plural handling needed.
+untitledTitle=dideitl-%S
+untitledDefaultFilename=dideitl
+ShowToolbar=Dangos Bar Offer
+HideToolbar=Cuddio'r Bar Offer
+ImapError=Methu llwytho'r ddelwedd\u0020
+ImapCheck=\nDewiswch leoliad (URL) newydd a cheisiwch eto.
+SaveToUseRelativeUrl=Dim ond ar dudalennau sydd wedi'u cadw mae modd defnyddio URL sy'n perthyn
+NoNamedAnchorsOrHeadings=(Nid oes angorau a enwyd na phenawdau ar y dudalen)
+TextColor=Lliw Testun
+HighlightColor=Lliw Amlygu
+PageColor=Lliw Cefndir Tudalen
+BlockColor=Rhwystro Cefndir Lliw
+TableColor=Lliw Cefndir Tabl
+CellColor=Lliw Cefndir Cell
+TableOrCellColor=Lliw Tabl neu Gell
+LinkColor=Lliw'r Testun Dolen
+ActiveLinkColor=Lliw Dolen Gweithredol
+VisitedLinkColor=Lliw Dolen Ymwelwyd
+NoColorError=Cliciwch ar liw neu roi llinyn lliw o HTML dilys
+Table=Tabl
+TableCell=Cell Tabl
+NestedTable=Tabl Nythwyd
+HLine=Llinell Llorweddol
+Link=Dolen
+Image=Delwedd
+ImageAndLink=Delwedd a Dolen
+NamedAnchor=Angor a Enwyd
+List=Rhestr
+ListItem=Rhestri'r eitem
+Form=Ffurflen
+InputTag=Maes Ffurflen
+InputImage=Delwedd Ffurflen
+TextArea=Ardal Testun
+Select=Rhestr Dewis
+Button=Botwm
+Label=Label
+FieldSet=Set Maes
+Tag=Tag
+MissingSiteNameError=Rhowch enw ar gyfer y wefan cyhoeddi.
+MissingPublishUrlError=Rhowch leoliad i gyhoeddi'r dudalen.
+MissingPublishFilename=Rhowch enw ffeil ar gyfer y dudalen gyfredol.
+#LOCALIZATION NOTE (DuplicateSiteNameError): Don't translate %name%
+DuplicateSiteNameError=Mae "%name%" yn bodoli eisoes. Rhowch enw safle gwahanol.
+AdvancedProperties=Priodweddau Uwch…
+AdvancedEditForCellMsg=Nid yw Golygu Uwch ar gael pan fydd celloedd niferus wedi'u dewis
+# LOCALIZATION NOTE (ObjectProperties):Don't translate "%obj%" it will be replaced with one of above object nouns
+ObjectProperties=Priodweddau %obj%…
+# LOCALIZATION NOTE This character must be in the above string and not confict with other accesskeys in Format menu
+ObjectPropertiesAccessKey=o
+# LOCALIZATION NOTE (JoinSelectedCells): This variable should contain the "tableJoinCells.accesskey" 
+# letter as defined in editorOverlay.dtd
+JoinSelectedCells=Uno'r Celloedd
+# LOCALIZATION NOTE (JoinCellToRight): This variable should contain the "tableJoinCells.accesskey" 
+# letter as defined in editorOverlay.dtd
+JoinCellToRight=Uno gyda'r Gell i'r Dde
+JoinCellAccesskey=j
+# LOCALIZATION NOTE (TableSelectKey): Ctrl key on a keyboard
+TableSelectKey=Ctrl+
+# LOCALIZATION NOTE (XulKeyMac): Command key on a Mac keyboard
+XulKeyMac=Cmd+
+# LOCALIZATION NOTE (Del): Del key on a keyboard
+Del=Del
+Delete=Dileu
+DeleteCells=Dileu Celloedd
+DeleteTableTitle=Dileu Rhesi neu Golofnau
+DeleteTableMsg=Bydd lleihau'r nifer o resi neu golofnau yn dileu celloedd tabl a'u cynnwys. Ydych chi wir eisiau gwneud hyn?
+Clear=Clirio
+#Mouse actions
+Click=Cliciwch
+Drag=Llusgo
+Unknown=Anhysbys
+#
+# LOCALIZATION NOTE "RemoveTextStylesAccesskey" is used for both
+#  menu items: "RemoveTextStyles" and "StopTextStyles"
+RemoveTextStylesAccesskey=x
+RemoveTextStyles=Tynnu Pob Arddull Testun
+StopTextStyles=Peidio Parhau gyda'r Arddulliau Testun
+#
+# LOCALIZATION NOTE "RemoveLinksAccesskey" is used for both
+#  menu items: "RemoveLinks" and "StopLinks"
+RemoveLinksAccesskey=n
+RemoveLinks=Tynnu Dolenni
+StopLinks=Peidio Parhau gyda'r Ddolen
+#
+NoFormAction=Awgrymir eich bod yn rhoi gweithred ar gyfer y ffurflen. Nid yw ffurflenni hunan gofnodi'n gweithio ar bob porwr am ei fod yn dechneg flaengar.
+NoAltText=Argymhellir eich bod yn darparu testun arall fydd yn ymddangos mewn porwyr testun yn unig, a fydd hefyd yn ymddangos mewn porwyr eraill pan fydd delwedd yn llwytho neu pan fo llwytho delwedd wedi'i analluogi.
+#
+Malformed=Nid oedd modd trosi'r ffynhonnell yn ôl i'r ddogfen am nad yw'n XHTML dilys.
+NoLinksToCheck=Does dim elfennau gyda chysylltiadau i'w gwirio
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/editorOverlay.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/editorOverlay.dtd
new file mode 100644
index 0000000000..d0e99b0b6d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/editorOverlay.dtd
@@ -0,0 +1,303 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- Attn: Localization - some of the menus in this dialog directly affect mail also. -->
+
+<!-- Edit menu items -->
+<!ENTITY pasteNoFormatting.label "Gludo heb fformatio">
+<!ENTITY pasteNoFormatting.accesskey "G">
+<!ENTITY pasteNoFormatting.key "V">
+<!ENTITY pasteAsQuotationCmd.label "Gludo fel Dyfyniad">
+<!ENTITY pasteAsQuotationCmd.accesskey "D">
+
+<!-- Insert menu items -->
+<!ENTITY insertMenu.label "Mewnosod">
+<!ENTITY insertMenu.accesskey "M">
+<!ENTITY insertLinkCmd2.label "Dolen…">
+<!ENTITY insertLinkCmd2.accesskey "D">
+<!ENTITY insertLinkCmd2.key "K">
+<!ENTITY insertAnchorCmd.label "Angor a Enwyd…">
+<!ENTITY insertAnchorCmd.accesskey "A">
+<!ENTITY insertImageCmd.label "Delwedd…">
+<!ENTITY insertImageCmd.accesskey "D">
+<!ENTITY insertHLineCmd.label "Llinell Llorweddol">
+<!ENTITY insertHLineCmd.accesskey "l">
+<!ENTITY insertTableCmd.label "Tabl…">
+<!ENTITY insertTableCmd.accesskey "T">
+<!ENTITY insertHTMLCmd.label "HTML…">
+<!ENTITY insertHTMLCmd.accesskey "H">
+<!ENTITY insertMathCmd.label "Mathemateg…">
+<!ENTITY insertMathCmd.accesskey "M">
+<!ENTITY insertCharsCmd.label "Nodau a Symbolau…">
+<!ENTITY insertCharsCmd.accesskey "N">
+<!ENTITY insertBreakAllCmd.label "Toriad Islaw Delwedd(au)">
+<!ENTITY insertBreakAllCmd.accesskey "I">
+
+<!-- Used just in context popup. -->
+<!ENTITY createLinkCmd.label "Creu Dolen…">
+<!ENTITY createLinkCmd.accesskey "D">
+<!ENTITY editLinkCmd.label "Golygu'r ddolen o fewn Cyfansoddwr Newydd">
+<!ENTITY editLinkCmd.accesskey "G">
+
+<!-- Font Face SubMenu -->
+<!ENTITY FontFaceSelect.tooltip "Dewiswch ffont">
+<!ENTITY fontfaceMenu.label "Ffont">
+<!ENTITY fontfaceMenu.accesskey "F">
+<!ENTITY fontVarWidth.label "Lled Newidiol">
+<!ENTITY fontVarWidth.accesskey "N">
+<!ENTITY fontFixedWidth.label "Lled Osodedig">
+<!ENTITY fontFixedWidth.accesskey "O">
+<!ENTITY fontFixedWidth.key "T">
+<!ENTITY fontHelvetica.label "Helvetica, Arial">
+<!ENTITY fontHelvetica.accesskey "l">
+<!ENTITY fontTimes.label "Times">
+<!ENTITY fontTimes.accesskey "T">
+<!ENTITY fontCourier.label "Courier">
+<!ENTITY fontCourier.accesskey "C">
+
+<!-- Font Size SubMenu -->
+<!ENTITY FontSizeSelect.tooltip "Dewiswch faint y ffont">
+<!ENTITY decreaseFontSize.label "Llai">
+<!ENTITY decreaseFontSize.accesskey "L">
+<!ENTITY decrementFontSize.key "&lt;">
+<!ENTITY decrementFontSize.key2 ","> <!-- < is above this key on many keyboards -->
+<!ENTITY increaseFontSize.label "Mwy">
+<!ENTITY increaseFontSize.accesskey "M">
+<!ENTITY incrementFontSize.key "&gt;">
+<!ENTITY incrementFontSize.key2 "."> <!-- > is above this key on many keyboards -->
+
+<!ENTITY fontSizeMenu.label "Maint">
+<!ENTITY fontSizeMenu.accesskey "M">
+<!ENTITY size-tinyCmd.label "Bach Iawn">
+<!ENTITY size-tinyCmd.accesskey "I">
+<!ENTITY size-smallCmd.label "Bach">
+<!ENTITY size-smallCmd.accesskey "B">
+<!ENTITY size-mediumCmd.label "Canolig">
+<!ENTITY size-mediumCmd.accesskey "C">
+<!ENTITY size-largeCmd.label "Mawr">
+<!ENTITY size-largeCmd.accesskey "M">
+<!ENTITY size-extraLargeCmd.label "Mawr Iawn">
+<!ENTITY size-extraLargeCmd.accesskey "w">
+<!ENTITY size-hugeCmd.label "Anferth">
+<!ENTITY size-hugeCmd.accesskey "A">
+
+<!-- Font Style SubMenu -->
+<!ENTITY fontStyleMenu.label "Arddull Testun">
+<!ENTITY fontStyleMenu.accesskey "A">
+<!ENTITY styleBoldCmd.label "Trwm">
+<!ENTITY styleBoldCmd.accesskey "T">
+<!ENTITY styleBoldCmd.key "B">
+<!ENTITY styleItalicCmd.label "Italig">
+<!ENTITY styleItalicCmd.accesskey "I">
+<!ENTITY styleItalicCmd.key "I">
+<!ENTITY styleUnderlineCmd.label "Tanlinellu">
+<!ENTITY styleUnderlineCmd.accesskey "a">
+<!ENTITY styleUnderlineCmd.key "U">
+<!ENTITY styleStrikeThruCmd.label "Taro drwodd">
+<!ENTITY styleStrikeThruCmd.accesskey "o">
+<!ENTITY styleSuperscriptCmd.label "Uwchysgrif">
+<!ENTITY styleSuperscriptCmd.accesskey "U">
+<!ENTITY styleSubscriptCmd.label "Isysgrif">
+<!ENTITY styleSubscriptCmd.accesskey "I">
+<!ENTITY styleNonbreakingCmd.label "Ddim yn torri">
+<!ENTITY styleNonbreakingCmd.accesskey "D">
+<!ENTITY styleEm.label "Pwyslais">
+<!ENTITY styleEm.accesskey "P">
+<!ENTITY styleStrong.label "Pwyslais Cryfach">
+<!ENTITY styleStrong.accesskey "C">
+<!ENTITY styleCite.label "Dyfyniad">
+<!ENTITY styleCite.accesskey "D">
+<!ENTITY styleAbbr.label "Byrfodd">
+<!ENTITY styleAbbr.accesskey "B">
+<!ENTITY styleAcronym.label "Acronym">
+<!ENTITY styleAcronym.accesskey "A">
+<!ENTITY styleCode.label "Cod">
+<!ENTITY styleCode.accesskey "o">
+<!ENTITY styleSamp.label "Sampl Allbwn">
+<!ENTITY styleSamp.accesskey "S">
+<!ENTITY styleVar.label "Newidiol">
+<!ENTITY styleVar.accesskey "N">
+
+<!ENTITY formatFontColor.label "Lliw'r Testun…">
+<!ENTITY formatFontColor.accesskey "L">
+<!ENTITY tableOrCellColor.label "Lliw Cefndir y Tabl neu'r Gell…">
+<!ENTITY tableOrCellColor.accesskey "C">
+
+<!ENTITY formatRemoveStyles.key "Y">
+<!ENTITY formatRemoveLinks.key "K">
+<!ENTITY formatRemoveNamedAnchors.label "Tynnu Angorau Enwyd">
+<!ENTITY formatRemoveNamedAnchors.accesskey "T">
+<!ENTITY formatRemoveNamedAnchors2.key "R">
+
+<!ENTITY paragraphMenu.label "Paragraff">
+<!ENTITY paragraphMenu.accesskey "P">
+<!ENTITY paragraphParagraphCmd.label "Paragraff">
+<!ENTITY paragraphParagraphCmd.accesskey "P">
+<!ENTITY heading1Cmd.label "Pennyn 1">
+<!ENTITY heading1Cmd.accesskey "1">
+<!ENTITY heading2Cmd.label "Pennyn 2">
+<!ENTITY heading2Cmd.accesskey "2">
+<!ENTITY heading3Cmd.label "Pennyn 3">
+<!ENTITY heading3Cmd.accesskey "3">
+<!ENTITY heading4Cmd.label "Pennyn 4">
+<!ENTITY heading4Cmd.accesskey "4">
+<!ENTITY heading5Cmd.label "Pennyn 5">
+<!ENTITY heading5Cmd.accesskey "5">
+<!ENTITY heading6Cmd.label "Pennyn 6">
+<!ENTITY heading6Cmd.accesskey "6">
+<!ENTITY paragraphAddressCmd.label "Cyfeiriad">
+<!ENTITY paragraphAddressCmd.accesskey "C">
+<!ENTITY paragraphPreformatCmd.label "Rhagfformatio">
+<!ENTITY paragraphPreformatCmd.accesskey "R">
+
+<!-- List menu items -->
+<!ENTITY formatlistMenu.label "Rhestr">
+<!ENTITY formatlistMenu.accesskey "R">
+<!ENTITY noneCmd.label "Dim">
+<!ENTITY noneCmd.accesskey "D">
+<!ENTITY listBulletCmd.label "Bwledwyd">
+<!ENTITY listBulletCmd.accesskey "B">
+<!ENTITY listNumberedCmd.label "Rhifwyd">
+<!ENTITY listNumberedCmd.accesskey "R">
+<!ENTITY listTermCmd.label "Term">
+<!ENTITY listTermCmd.accesskey "T">
+<!ENTITY listDefinitionCmd.label "Diffiniad">
+<!ENTITY listDefinitionCmd.accesskey "D">
+<!ENTITY listPropsCmd.label "Priodweddau'r Rhestr…">
+<!ENTITY listPropsCmd.accesskey "R">
+
+<!ENTITY ParagraphSelect.tooltip "Dewiswch fformat paragraff">
+<!-- Shared in Paragraph, and Toolbar menulist -->
+<!ENTITY bodyTextCmd.label "Corff y Testun">
+<!ENTITY bodyTextCmd.accesskey "C">
+
+<!-- Align menu items -->
+<!ENTITY alignMenu.label "Alinio">
+<!ENTITY alignMenu.accesskey "A">
+<!ENTITY alignLeft.label "Chwith">
+<!ENTITY alignLeft.accesskey "C">
+<!ENTITY alignLeft.tooltip "Alinio i'r Chwith">
+<!ENTITY alignCenter.label "Canol">
+<!ENTITY alignCenter.accesskey "a">
+<!ENTITY alignCenter.tooltip "Alinio i'r Canol">
+<!ENTITY alignRight.label "De">
+<!ENTITY alignRight.accesskey "D">
+<!ENTITY alignRight.tooltip "Alinio i'r Dde">
+<!ENTITY alignJustify.label "Unioni">
+<!ENTITY alignJustify.accesskey "U">
+<!ENTITY alignJustify.tooltip "Alinio Unioni">
+
+<!ENTITY increaseIndent.label "Cynyddu'r Mewnoliad">
+<!ENTITY increaseIndent.accesskey "y">
+<!ENTITY increaseIndent.key "]">
+<!ENTITY decreaseIndent.label "Lleihau Mewnoliad">
+<!ENTITY decreaseIndent.accesskey "L">
+<!ENTITY decreaseIndent.key "[">
+
+<!ENTITY colorsAndBackground.label "Lliwiau Tudalen a Chefndir…">
+<!ENTITY colorsAndBackground.accesskey "L">
+
+<!-- Table Menu -->
+<!ENTITY tableMenu.label "Tabl">
+<!ENTITY tableMenu.accesskey "b">
+
+<!-- Select Submenu -->
+<!ENTITY tableSelectMenu.label "Dewis">
+<!ENTITY tableSelectMenu.accesskey "D">
+
+<!ENTITY tableSelectMenu2.label "Dewis Tabl">
+<!ENTITY tableSelectMenu2.accesskey "T">
+<!ENTITY tableInsertMenu2.label "Mewnosod Tabl">
+<!ENTITY tableInsertMenu2.accesskey "M">
+<!ENTITY tableDeleteMenu2.label "Dileu Tabl">
+<!ENTITY tableDeleteMenu2.accesskey "D">
+
+<!-- Insert SubMenu -->
+<!ENTITY tableInsertMenu.label "Mewnosod">
+<!ENTITY tableInsertMenu.accesskey "M">
+<!ENTITY tableTable.label "Tabl">
+<!ENTITY tableTable.accesskey "T">
+<!ENTITY tableRow.label "Rhes">
+<!ENTITY tableRows.label "Rhes(i)">
+<!ENTITY tableRow.accesskey "R">
+<!ENTITY tableRowAbove.label "Rhes Uwchben">
+<!ENTITY tableRowAbove.accesskey "U">
+<!ENTITY tableRowBelow.label "Rhes Islaw">
+<!ENTITY tableRowBelow.accesskey "I">
+<!ENTITY tableColumn.label "Colofn">
+<!ENTITY tableColumns.label "Colofn(au)">
+<!ENTITY tableColumn.accesskey "o">
+<!ENTITY tableColumnBefore.label "Colofn Cynt">
+<!ENTITY tableColumnBefore.accesskey "y">
+<!ENTITY tableColumnAfter.label "Colofn yn Dilyn">
+<!ENTITY tableColumnAfter.accesskey "D">
+<!ENTITY tableCell.label "Cell">
+<!ENTITY tableCells.label "Cell(oedd)">
+<!ENTITY tableCell.accesskey "C">
+<!ENTITY tableCellContents.label "Cynnwys Cell">
+<!ENTITY tableCellContents.accesskey "y">
+<!ENTITY tableAllCells.label "Pob Cell">
+<!ENTITY tableAllCells.accesskey "P">
+<!ENTITY tableCellBefore.label "Cell Cynt">
+<!ENTITY tableCellBefore.accesskey "e">
+<!ENTITY tableCellAfter.label "Cell yn Dilyn">
+<!ENTITY tableCellAfter.accesskey "i">
+<!-- Delete SubMenu -->
+<!ENTITY tableDeleteMenu.label "Dileu">
+<!ENTITY tableDeleteMenu.accesskey "D">
+
+<!-- text for "Join Cells" is in editor.properties
+     ("JoinSelectedCells" and "JoinCellToRight")
+     the access key must exist in both of those strings
+     But value must be set here for accesskey to draw properly
+-->
+<!ENTITY tableJoinCells.label "j">
+<!ENTITY tableJoinCells.accesskey "j">
+<!ENTITY tableSplitCell.label "Rhannu Cell">
+<!ENTITY tableSplitCell.accesskey "R">
+<!ENTITY convertToTable.label "Creu Tabl o'r Dewis">
+<!ENTITY convertToTable.accesskey "D">
+<!ENTITY tableProperties.label "Priodweddau Tabl…">
+<!ENTITY tableProperties.accesskey "P">
+
+<!ENTITY imageToolbarCmd.label "Delwedd">
+<!ENTITY imageToolbarCmd.tooltip "Mewnosod delwedd newydd neu olygu priodweddau'r ddelwedd">
+<!ENTITY hruleToolbarCmd.label "H.Line">
+<!ENTITY hruleToolbarCmd.tooltip "Mewnosod llinell lorweddol neu olygu priodweddau'r ddelwedd">
+<!ENTITY tableToolbarCmd.label "Tabl">
+<!ENTITY tableToolbarCmd.tooltip "Mewnosod tabl newydd neu olygu priodweddau'r tabl">
+<!ENTITY linkToolbarCmd.label "Dolen">
+<!ENTITY linkToolbarCmd.tooltip "Mewnosod dolen newydd neu olygu priodweddau'r ddolen">
+<!ENTITY anchorToolbarCmd.label "Angor">
+<!ENTITY anchorToolbarCmd.tooltip "Mewnosod angor a enwyd neu olygu priodweddau'r angor">
+<!ENTITY TextColorButton.tooltip "Dewiswch liw i'r testun">
+<!ENTITY BackgroundColorButton.tooltip "Dewiswch liw i'r cefndir">
+
+<!-- Editor toolbar -->
+<!ENTITY absoluteFontSizeToolbarCmd.tooltip "Gosod maint ffont">
+<!ENTITY decreaseFontSizeToolbarCmd.tooltip "Maint ffont lai">
+<!ENTITY increaseFontSizeToolbarCmd.tooltip "Maint ffont mwy">
+<!ENTITY boldToolbarCmd.tooltip "Trwm">
+<!ENTITY italicToolbarCmd.tooltip "Italig">
+<!ENTITY underlineToolbarCmd.tooltip "Tanlinellu">
+<!ENTITY bulletListToolbarCmd.tooltip "Gosod neu ddiddymu rhestr bwledi">
+<!ENTITY numberListToolbarCmd.tooltip "Gosod neu ddiddymu rhestr rhifedig">
+<!ENTITY outdentToolbarCmd.tooltip "Alloliad testun (symud i'r chwith)">
+<!ENTITY indentToolbarCmd.tooltip "Mewnoliad testun (symud i'r dde)">
+<!ENTITY AlignPopupButton.tooltip "Dewis aliniad testun">
+<!ENTITY InsertPopupButton.tooltip "Mewnosod Dolen, Angor, Delwedd, Llinell Lorweddol neu Dabl">
+<!ENTITY alignLeftButton.tooltip "Alinio testun ar hyd yr ymyl chwith">
+<!ENTITY alignCenterButton.tooltip "Alinio testun wedi'i ganoli">
+<!ENTITY alignRightButton.tooltip "Alinio testun ar hyd yr ymyl dde">
+<!ENTITY alignJustifyButton.tooltip "Alinio testun ar hyd ymylon de a chwith">
+
+<!-- TOC manipulation -->
+<!ENTITY insertTOC.label          "Mewnosod">
+<!ENTITY insertTOC.accesskey      "M">
+<!ENTITY updateTOC.label          "Diweddaru">
+<!ENTITY updateTOC.accesskey      "u">
+<!ENTITY removeTOC.label          "Tynnu">
+<!ENTITY removeTOC.accesskey      "T">
+<!ENTITY tocMenu.label            "Tabl Cynnwys…">
+<!ENTITY tocMenu.accesskey        "C">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/mailComposeEditorOverlay.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/mailComposeEditorOverlay.dtd
new file mode 100644
index 0000000000..331520180c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/mailComposeEditorOverlay.dtd
@@ -0,0 +1,9 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY attachImageSource.label         "Atodi'r ddelwedd i'r neges">
+<!ENTITY attachImageSource.accesskey     "d">
+
+<!ENTITY attachLinkSource.label          "Atodi ffynhonnell y ddolen i'r neges">
+<!ENTITY attachLinkSource.accesskey      "f">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/messengercompose.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/messengercompose.dtd
new file mode 100644
index 0000000000..3cfa590bab
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/messengercompose.dtd
@@ -0,0 +1,306 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE messengercompose.dtd Main UI for message composition -->
+<!ENTITY msgComposeWindow.title "Ysgrifennu: (dim pwnc)">
+
+<!-- File Menu -->
+<!ENTITY fileMenu.label "Ffeil">
+<!ENTITY fileMenu.accesskey "F">
+<!ENTITY newMenu.label "Newydd">
+<!ENTITY newMenu.accesskey "N">
+<!ENTITY newMessage.label "Neges">
+<!ENTITY newMessage.accesskey "N">
+<!ENTITY newMessageCmd2.key "N">
+<!ENTITY newContact.label "Cysylltiad Llyfr Cyfeiriadau…">
+<!ENTITY newContact.accesskey "C">
+<!ENTITY attachMenu.label "Atodi">
+<!ENTITY attachMenu.accesskey "A">
+<!ENTITY attachCloudCmd.label "Filelink">
+<!ENTITY attachCloudCmd.accesskey "F">
+<!ENTITY attachPageCmd.label "Tudalen Gwe…">
+<!ENTITY attachPageCmd.accesskey "T">
+<!ENTITY remindLater.label "Atgoffa Fi yn Ddiweddarach">
+<!ENTITY remindLater.accesskey "D">
+<!ENTITY closeCmd.label "Cau">
+<!ENTITY closeCmd.key "W">
+<!ENTITY closeCmd.accesskey "u">
+<!ENTITY saveCmd.label "Cadw">
+<!ENTITY saveCmd.key "S">
+<!ENTITY saveCmd.accesskey "C">
+<!ENTITY saveAsCmd.label "Cadw Fel">
+<!ENTITY saveAsCmd.accesskey "d">
+<!ENTITY saveAsFileCmd.label "Ffeil…">
+<!ENTITY saveAsFileCmd.accesskey "F">
+<!ENTITY saveAsDraftCmd.label "Drafft">
+<!ENTITY saveAsDraftCmd.accesskey "D">
+<!ENTITY saveAsTemplateCmd.label "Templed">
+<!ENTITY saveAsTemplateCmd.accesskey "T">
+<!ENTITY sendNowCmd.label "Anfon Nawr">
+<!ENTITY sendCmd.keycode "VK_RETURN">
+<!ENTITY sendNowCmd.accesskey "A">
+<!ENTITY sendLaterCmd.label "Anfon yn Diweddarach">
+<!ENTITY sendLaterCmd.keycode "VK_RETURN">
+<!ENTITY sendLaterCmd.accesskey "D">
+<!ENTITY printCmd.label "Argraffu…">
+<!ENTITY printCmd.key "P">
+<!ENTITY printCmd.accesskey "A">
+
+<!-- Edit Menu -->
+<!ENTITY editMenu.label "Golygu">
+<!ENTITY editMenu.accesskey "G">
+<!ENTITY undoCmd.label "Dadwneud">
+<!ENTITY undoCmd.key "Z">
+<!ENTITY undoCmd.accesskey "u">
+<!ENTITY redoCmd.label "Ailwneud">
+<!ENTITY redoCmd.key "Y">
+<!ENTITY redoCmd.accesskey "A">
+<!ENTITY cutCmd.key "X">
+<!ENTITY copyCmd.key "C">
+<!ENTITY pasteCmd.key "V">
+<!ENTITY pasteNoFormattingCmd.key "V">
+<!ENTITY pasteAsQuotationCmd.key "o">
+<!ENTITY editRewrapCmd.accesskey "i">
+<!ENTITY deleteCmd.label "Dileu">
+<!ENTITY deleteCmd.accesskey "D">
+<!ENTITY editRewrapCmd.label "Ail-lapio">
+<!ENTITY editRewrapCmd.key "R">
+<!ENTITY renameAttachmentCmd.label "Ailenwi Atodiad…">
+<!ENTITY renameAttachmentCmd.accesskey "A">
+<!ENTITY reorderAttachmentsCmd.label "Aildrefnu Atodiadau…">
+<!ENTITY reorderAttachmentsCmd.accesskey "A">
+<!ENTITY reorderAttachmentsCmd.key "x">
+<!ENTITY selectAllCmd.accesskey "D">
+<!ENTITY findBarCmd.label "Canfod…">
+<!ENTITY findBarCmd.accesskey "f">
+<!ENTITY findBarCmd.key "F">
+<!ENTITY findReplaceCmd.label "Canfod ac Amnewid…">
+<!ENTITY findReplaceCmd.accesskey "N">
+<!ENTITY findReplaceCmd.key "H">
+<!ENTITY findAgainCmd.label "Canfod Eto">
+<!ENTITY findAgainCmd.accesskey "E">
+<!ENTITY findAgainCmd.key "G">
+<!ENTITY findAgainCmd.key2 "VK_F3">
+<!ENTITY findPrevCmd.label "Canfod Blaenorol">
+<!ENTITY findPrevCmd.accesskey "B">
+<!ENTITY findPrevCmd.key "G">
+<!ENTITY findPrevCmd.key2 "VK_F3">
+
+<!-- Reorder Attachment Panel -->
+<!ENTITY reorderAttachmentsPanel.label "Aildrefnu Atodiadau">
+<!ENTITY moveAttachmentBundleUpPanelBtn.label "Symud gyda'i gilydd">
+
+<!-- LOCALIZATION NOTE (sortAttachmentsPanelBtn.Sort.AZ.label):
+     Please ensure that this translation matches
+     sortAttachmentsPanelBtn.Sort.ZA.label, except for the sort direction. -->
+<!ENTITY sortAttachmentsPanelBtn.Sort.AZ.label "Trefnu: A - Z">
+<!ENTITY sortAttachmentsPanelBtn.Sort.ZA.label "Trefnu: Z - A">
+<!-- LOCALIZATION NOTE (sortAttachmentsPanelBtn.SortSelection.AZ.label):
+     Please ensure that this translation matches
+     sortAttachmentsPanelBtn.SortSelection.ZA.label, except for the sort direction. -->
+<!ENTITY sortAttachmentsPanelBtn.SortSelection.AZ.label "Trefnu'r Dewis: A - Z">
+<!ENTITY sortAttachmentsPanelBtn.SortSelection.ZA.label "Trefnu'r Dewis: Z - A">
+<!ENTITY sortAttachmentsPanelBtn.key "t">
+
+<!-- View Menu -->
+<!ENTITY viewMenu.label "Golwg">
+<!ENTITY viewMenu.accesskey "l">
+<!ENTITY viewToolbarsMenuNew.label "Barrau Offer">
+<!ENTITY viewToolbarsMenuNew.accesskey "B">
+<!ENTITY menubarCmd.label "Bar Dewislen">
+<!ENTITY menubarCmd.accesskey "D">
+<!ENTITY showCompositionToolbarCmd.label "Bar Offer Ysgrifennu">
+<!ENTITY showCompositionToolbarCmd.accesskey "Y">
+<!ENTITY showFormattingBarCmd.label "Bar Offer Fformatio">
+<!ENTITY showFormattingBarCmd.accesskey "F">
+<!ENTITY showTaskbarCmd.label "Bar Statws">
+<!ENTITY showTaskbarCmd.accesskey "S">
+<!ENTITY customizeToolbar.label "Cyfaddasu…">
+<!ENTITY customizeToolbar.accesskey "C">
+
+<!ENTITY addressSidebar.label "Bar Ochr Cysylltiadau">
+<!ENTITY addressSidebar.accesskey "O">
+
+<!-- Format Menu -->
+<!ENTITY formatMenu.label "Fformat">
+<!ENTITY formatMenu.accesskey "o">
+
+<!-- Options Menu -->
+<!ENTITY optionsMenu.label "Dewisiadau">
+<!ENTITY optionsMenu.accesskey "D">
+<!ENTITY checkSpellingCmd2.label "Gwirio Sillafu…">
+<!ENTITY checkSpellingCmd2.key "p">
+<!ENTITY checkSpellingCmd2.key2 "VK_F7">
+<!ENTITY checkSpellingCmd2.accesskey "G">
+<!ENTITY enableInlineSpellChecker.label "Gwirio Sillafu wrth Deipio">
+<!ENTITY enableInlineSpellChecker.accesskey "D">
+<!ENTITY quoteCmd.label "Dyfynnu Neges">
+<!ENTITY quoteCmd.accesskey "N">
+
+<!--LOCALIZATION NOTE attachVCard.label Don't translate the term 'vCard' -->
+<!ENTITY attachVCard.label "Atodi Cerdyn Personol (vCard)">
+<!ENTITY attachVCard.accesskey "v">
+
+<!ENTITY returnReceiptMenu.label "Derbynneb Dychwelyd">
+<!ENTITY returnReceiptMenu.accesskey "D">
+<!ENTITY dsnMenu.label "Hysbysiad Statws Trosglwyddo">
+<!ENTITY dsnMenu.accesskey "H">
+<!ENTITY priorityMenu.label "Blaenoriaeth">
+<!ENTITY priorityMenu.accesskey "B">
+<!ENTITY priorityButton.title "Blaenoriaeth">
+<!ENTITY priorityButton.tooltiptext "Newid blaenoriaethau negeseuon">
+<!ENTITY priorityButton.label "Blaenoriaeth:">
+<!ENTITY lowestPriorityCmd.label "Isaf">
+<!ENTITY lowestPriorityCmd.accesskey "I">
+<!ENTITY lowPriorityCmd.label "Isel">
+<!ENTITY lowPriorityCmd.accesskey "s">
+<!ENTITY normalPriorityCmd.label "Arferol">
+<!ENTITY normalPriorityCmd.accesskey "A">
+<!ENTITY highPriorityCmd.label "Uchel">
+<!ENTITY highPriorityCmd.accesskey "c">
+<!ENTITY highestPriorityCmd.label "Uchaf">
+<!ENTITY highestPriorityCmd.accesskey "U">
+<!ENTITY fileCarbonCopyCmd.label "Anfon Copi At">
+<!ENTITY fileCarbonCopyCmd.accesskey "A">
+<!ENTITY fileHereMenu.label "Ffeilio Yma">
+
+<!-- Tools Menu -->
+<!ENTITY tasksMenu.label "Offer">
+<!ENTITY tasksMenu.accesskey "O">
+<!ENTITY messengerCmd.label "E-bost a Grwpiau Newyddion">
+<!ENTITY messengerCmd.accesskey "b">
+<!ENTITY messengerCmd.commandkey "1">
+<!ENTITY addressBookCmd.label "Llyfr Cyfeiriadau">
+<!ENTITY addressBookCmd.accesskey "L">
+<!ENTITY addressBookCmd.key "B">
+<!ENTITY accountManagerCmd2.label "Gosodiadau'r Cyfrif">
+<!ENTITY accountManagerCmd2.accesskey "C">
+<!ENTITY accountManagerCmdUnix2.accesskey "C">
+
+<!--  Mac OS X Window Menu -->
+<!ENTITY minimizeWindow.key "m">
+<!ENTITY minimizeWindow.label "Lleihau">
+<!ENTITY bringAllToFront.label "Dod â'r Cyfan i'r Blaen">
+<!ENTITY zoomWindow.label "Chwyddo">
+<!ENTITY windowMenu.label "Ffenestr">
+
+<!-- Mail Toolbar -->
+<!ENTITY sendButton.label "Anfon">
+<!ENTITY quoteButton.label "Dyfynnu">
+<!ENTITY addressButton.label "Cysylltiadau">
+<!ENTITY spellingButton.label "Sillafu">
+<!ENTITY saveButton.label "Cadw">
+<!ENTITY printButton.label "Argraffu">
+
+<!-- Mail Toolbar Tooltips -->
+<!ENTITY sendButton.tooltip "Anfon y neges nawr">
+<!ENTITY sendlaterButton.tooltip "Anfonwch y neges yn ddiweddarach">
+<!ENTITY quoteButton.tooltip "Dyfynnu'r neges flaenorol">
+<!ENTITY addressButton.tooltip "Dewis derbynnydd o'r Llyfr Cyfeiriadau">
+<!ENTITY spellingButton.tooltip "Gwirio sillafu adran neu neges gyfan">
+<!ENTITY saveButton.tooltip "Cadw'r neges">
+<!ENTITY cutButton.tooltip              "Torri">
+<!ENTITY copyButton.tooltip             "Copïo">
+<!ENTITY pasteButton.tooltip            "Gludo">
+<!ENTITY printButton.tooltip "Argraffu'r neges">
+
+<!-- Headers -->
+<!--LOCALIZATION NOTE headersSpaces.style is for aligning  the From:, To: and
+    Subject: rows. It should be larger than the largest Header label  -->
+<!ENTITY headersSpace2.style "width: 8em;">
+<!ENTITY fromAddr2.label "Oddi wrth">
+<!ENTITY fromAddr.accesskey "O">
+<!ENTITY replyAddr2.label "Ateb i">
+<!ENTITY newsgroupsAddr2.label "Grŵp Newyddion">
+<!ENTITY followupAddr2.label "Dilyn i">
+<!ENTITY subject2.label "Pwnc">
+<!ENTITY subject.accesskey "P">
+<!ENTITY attachmentBucketCloseButton.tooltip "Cuddio'r paen atodiad">
+
+<!-- Format Toolbar, imported from editorAppShell.xhtml -->
+<!ENTITY SmileButton.tooltip "Mewnosod wyneb gwenog">
+<!ENTITY smiley1Cmd.label "Gwên">
+<!ENTITY smiley2Cmd.label "Gwg">
+<!ENTITY smiley3Cmd.label "Winc">
+<!ENTITY smiley4Cmd.label "Tafod allan">
+<!ENTITY smiley5Cmd.label "Chwerthin">
+<!ENTITY smiley6Cmd.label "Embaras">
+<!ENTITY smiley7Cmd.label "Heb benderfynu">
+<!ENTITY smiley8Cmd.label "Syndod">
+<!ENTITY smiley9Cmd.label "Cusan">
+<!ENTITY smiley10Cmd.label "Gwaedd">
+<!ENTITY smiley11Cmd.label "Cwl">
+<!ENTITY smiley12Cmd.label "Ceg Aur">
+<!ENTITY smiley13Cmd.label "Ceg Fawr">
+<!ENTITY smiley14Cmd.label "Diniwed">
+<!ENTITY smiley15Cmd.label "Crio">
+<!ENTITY smiley16Cmd.label "Dim Gair!">
+
+<!-- Message Pane Context Menu -->
+<!ENTITY spellCheckNoSuggestions.label "Heb Ganfod Awgrymiadau">
+<!ENTITY spellCheckIgnoreWord.label "Anwybyddu Gair">
+<!ENTITY spellCheckIgnoreWord.accesskey "A">
+<!ENTITY spellCheckAddToDictionary.label "Ychwanegu i'r Geiriadur">
+<!ENTITY spellCheckAddToDictionary.accesskey "n">
+<!ENTITY undo.label "Dadwneud">
+<!ENTITY undo.accesskey "u">
+<!ENTITY cut.label "Torri">
+<!ENTITY cut.accesskey "T">
+<!ENTITY copy.label "Copïo">
+<!ENTITY copy.accesskey "C">
+<!ENTITY paste.label "Gludo">
+<!ENTITY paste.accesskey "G">
+<!ENTITY pasteQuote.label "Gludo fel Dyfyniad">
+<!ENTITY pasteQuote.accesskey "D">
+
+<!-- Attachment Item and List Context Menus -->
+<!ENTITY openAttachment.label "Agor">
+<!ENTITY openAttachment.accesskey "o">
+<!ENTITY delete.label "Dileu">
+<!ENTITY delete.accesskey "D">
+<!ENTITY removeAttachment.label "Tynnu Atodiad">
+<!ENTITY removeAttachment.accesskey "y">
+<!ENTITY renameAttachment.label "Ailenwi…">
+<!ENTITY renameAttachment.accesskey "A">
+<!ENTITY reorderAttachments.label "Aildrefnu Atodiadau…">
+<!ENTITY reorderAttachments.accesskey "a">
+<!ENTITY removeAllAttachments.label "Tynnu Pob Atodiad">
+<!ENTITY removeAllAttachments.accesskey "T">
+<!ENTITY selectAll.label "Dewis Popeth">
+<!ENTITY selectAll.accesskey "D">
+<!ENTITY attachCloud.label "Filelink…">
+<!ENTITY attachCloud.accesskey "i">
+<!ENTITY convertCloud.label "Trosi i…">
+<!ENTITY convertCloud.accesskey "T">
+<!ENTITY cancelUpload.label "Diddymu'r Llwytho i Fyny">
+<!ENTITY cancelUpload.accesskey "D">
+<!ENTITY convertRegularAttachment.label "Atodiad Arferol">
+<!ENTITY convertRegularAttachment.accesskey "A">
+<!ENTITY attachPage.label "Atodi Tudalen Gwe…">
+<!ENTITY attachPage.accesskey "T">
+
+<!-- Attachment Pane Header Bar Context Menu -->
+<!-- LOCALIZATION NOTE (initiallyShowAttachmentPane.label):
+     Should use the same wording as startExpandedCmd.label
+     in msgHdrViewOverlay.dtd. -->
+<!ENTITY initiallyShowAttachmentPane.label "Dangos y Paen Atodi yn Gyntaf">
+<!ENTITY initiallyShowAttachmentPane.accesskey "D">
+
+<!-- Spell checker context menu items -->
+<!ENTITY spellAddDictionaries.label "Ychwanegu Geiriaduron…">
+<!ENTITY spellAddDictionaries.accesskey "G">
+
+<!-- Title for the address picker panel -->
+<!ENTITY addressesSidebarTitle.label "Cysylltiadau">
+
+<!-- Identity popup customize menuitem -->
+<!ENTITY customizeFromAddress.label "Cyfaddasu Cyfeiriad Oddi Wrth…">
+<!ENTITY customizeFromAddress.accesskey "O">
+
+<!-- Accessibility name for the document -->
+<!ENTITY aria.message.bodyName "Corff neges">
+
+<!-- Status Bar -->
+<!ENTITY languageStatusButton.tooltip "Iaith gwirio sillafu">
+<!ENTITY encodingStatusPanel.tooltip "Amgodiad testun">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/sendProgress.dtd b/l10n-cy/mail/chrome/messenger/messengercompose/sendProgress.dtd
new file mode 100644
index 0000000000..0bc736e9f1
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/sendProgress.dtd
@@ -0,0 +1,8 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!--LOCALIZATION NOTE sendProgress.dtd Main UI for Send Message Progress Dialog -->
+
+<!ENTITY sendDialog.title "Prosesu Neges">
+<!ENTITY status.label "Statws:">
+<!ENTITY progress.label "Cynnydd:">
diff --git a/l10n-cy/mail/chrome/messenger/messengercompose/sendProgress.properties b/l10n-cy/mail/chrome/messenger/messengercompose/sendProgress.properties
new file mode 100644
index 0000000000..2682ce0cf3
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/messengercompose/sendProgress.properties
@@ -0,0 +1,21 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (titleSendMsgSubject):
+# %S will be replaced by the message subject.
+titleSendMsgSubject=Anfon Neges - %S
+titleSendMsg=Anfon Neges
+# LOCALIZATION NOTE (titleSaveMsgSubject):
+# %S will be replaced by the message subject.
+titleSaveMsgSubject=Cadw Neges - %S
+titleSaveMsg=Cadw Neges
+
+# LOCALIZATION NOTE (percentMsg):
+# This string is used to format the text to the right of the progress meter.
+# %S will be replaced by the percentage of the file that has been saved.
+# %% will be replaced a single % sign.
+percentMsg=%S%%
+
+messageSent=Mae eich negeseuon wedi'u hanfon.
+messageSaved=Mae eich negeseuon wedi'u cadw.
diff --git a/l10n-cy/mail/chrome/messenger/migration/migration.dtd b/l10n-cy/mail/chrome/messenger/migration/migration.dtd
new file mode 100644
index 0000000000..c971fb91ae
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/migration/migration.dtd
@@ -0,0 +1,30 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+
+<!ENTITY migrationWizard.title          "Dewin Mewnforio">
+
+<!ENTITY importFromWin.label            "Dewisiadau Mewnforio, Nodau Tudalen, Hanes, Cyfrineiriau, a data arall o:">
+<!ENTITY importFromNonWin.label         "Dewisiadau Mewnforio, Nodau Tudalen, Hanes, Cyfrineiriau a data arall o:">
+<!ENTITY importSourceNotFound.label     "Heb ganfod rhaglen i fewnforio data ohoni.">
+
+<!ENTITY importFromNothing.label        "Peidio mewnforio dim">
+<!ENTITY importFromNothing.accesskey    "P">
+<!ENTITY importFromSeamonkey3.label     "SeaMonkey 2 neu'r diweddarach">
+<!ENTITY importFromSeamonkey3.accesskey "S">
+<!ENTITY importFromOutlook.label        "Outlook">
+<!ENTITY importFromOutlook.accesskey    "O">
+
+<!ENTITY importSource.title             "Gosodiadau Mewnforio a Ffolderi E-bost">
+<!ENTITY importItems.title              "Eitemau i'w Mewnforio">
+<!ENTITY importItems.label              "Dewis eitemau i'w mewnforio:">
+
+<!ENTITY migrating.title                "Mewnforio…">
+<!ENTITY migrating.label                "Mae'r eitemau canlynol yn cael eu mewnforio…">
+
+<!ENTITY selectProfile.title            "Dewis Proffil">
+<!ENTITY selectProfile.label            "Mae'r proffiliau canlynol ar gael i'w mewnforio o:">
+
+<!ENTITY done.title                     "Wedi Cwblhau Mewnforio">
+<!ENTITY done.label                     "Cafodd yr eitemau canlynol eu mewnforio'n llwyddiannus:">
diff --git a/l10n-cy/mail/chrome/messenger/migration/migration.properties b/l10n-cy/mail/chrome/messenger/migration/migration.properties
new file mode 100644
index 0000000000..1c52efbc8c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/migration/migration.properties
@@ -0,0 +1,32 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+profileName_format=%S %S
+
+# Import Sources
+1_seamonkey=Dewisiadau
+
+1_thunderbird=Dewisiadau
+
+2_seamonkey=Gosodiadau'r Cyfrif
+2_thunderbird=Gosodiadau Cyfrif
+2_outlook=Gosodiadau'r Cyfrif
+
+4_seamonkey=Llyfrau Cyfeiriadau
+4_thunderbird=Llyfrau Cyfeiriadau
+4_outlook=Llyfr Cyfeiriadau
+
+8_seamonkey=Hyfforddiant Sbam
+
+16_seamonkey=Cyfrineiriau a Gadwyd
+
+32_seamonkey=Data Arall
+
+64_seamonkey=Ffolderi Grwpiau Newyddion
+
+64_thunderbird=Ffolderi Grwpiau Newyddion
+
+128_seamonkey=Ffolderi E-bost
+128_thunderbird=Ffolderi E-bost
+128_outlook=Ffolderi E-bost
diff --git a/l10n-cy/mail/chrome/messenger/mime.properties b/l10n-cy/mail/chrome/messenger/mime.properties
new file mode 100644
index 0000000000..f4e27121ca
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/mime.properties
@@ -0,0 +1,154 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by libmime to emit header display in HTML
+#
+
+# Mail subject
+## @name MIME_MHTML_SUBJECT
+## @loc None
+1000=Pwnc
+
+# Resent-Comments
+## @name MIME_MHTML_RESENT_COMMENTS
+## @loc 
+1001=Ailanfonwyd-Sylwadau
+
+# Resent-Date
+## @name MIME_MHTML_RESENT_DATE
+## @loc 
+1002=Ailanfonwyd-Dyddiad
+
+# Resent-Sender
+## @name MIME_MHTML_RESENT_SENDER
+## @loc 
+1003=Ailanfonwyd-Anfonwr
+
+# Resent-From
+## @name MIME_MHTML_RESENT_FROM
+## @loc 
+1004=Ailanfonwyd-Oddi wrth
+
+# Resent-To
+## @name MIME_MHTML_RESENT_TO
+## @loc 
+1005=Ailanfonwyd-At
+
+# Resent-CC
+## @name MIME_MHTML_RESENT_CC
+## @loc 
+1006=Ailanfonwyd-CC
+
+# Date
+## @name MIME_MHTML_DATE
+## @loc 
+1007=Dyddiad
+
+# Sender
+## @name MIME_MHTML_SENDER
+## @loc 
+1008=Anfonwr
+
+# From
+## @name MIME_MHTML_FROM
+## @loc 
+1009=Oddi wrth
+
+# Reply-To
+## @name MIME_MHTML_REPLY_TO
+## @loc 
+1010=Ateb-At
+
+# Organization
+## @name MIME_MHTML_ORGANIZATION
+## @loc 
+1011=Corff
+
+# To
+## @name MIME_MHTML_TO
+## @loc 
+1012=I
+
+# CC
+## @name MIME_MHTML_CC
+## @loc 
+1013=CC
+
+# Newsgroups
+## @name MIME_MHTML_NEWSGROUPS
+## @loc 
+1014=Grwpiau Newyddion
+
+# Followup-To
+## @name MIME_MHTML_FOLLOWUP_TO
+## @loc 
+1015=Dilyn-At
+
+# References
+## @name MIME_MHTML_REFERENCES
+## @loc 
+1016=Cyfeirnodau
+
+# Message ID
+## @name MIME_MHTML_MESSAGE_ID
+## @loc 
+1021=Neges-Enw
+
+# BCC
+## @name MIME_MHTML_BCC
+## @loc 
+1023=BCC
+
+# Link to doc
+## @name MIME_MSG_LINK_TO_DOCUMENT
+## @loc 
+1026=Cysylltu â Ddogfen
+
+# Get Doc info
+## @name MIME_MSG_DOCUMENT_INFO
+## @loc 
+1027=<B>Gwybodaeth am Ddogfen:</B>
+
+# Msg Attachment
+## @name MIME_MSG_ATTACHMENT
+## @loc 
+1028=Atodiad
+
+# default attachment name
+## @name MIME_MSG_DEFAULT_ATTACHMENT_NAME
+## @loc 
+# LOCALIZATION NOTE (1040): Do not translate "%s" below.
+# Place the %s where you wish the part number of the attachment to appear
+1040=Rhan %s
+
+# default forwarded message prefix
+## @name MIME_FORWARDED_MESSAGE_HTML_USER_WROTE
+## @loc 
+1041=-------- Neges Wreiddiol --------
+
+# Partial Message Truncated
+## @name MIME_MSG_PARTIAL_TRUNCATED
+## @loc
+MIME_MSG_PARTIAL_TRUNCATED=Tociwyd!
+
+# Partial Message Truncated Explanation
+## @name MIME_MSG_PARTIAL_TRUNCATED_EXPLANATION
+## @loc
+MIME_MSG_PARTIAL_TRUNCATED_EXPLANATION=Mae'r neges yn fwy na Maint Neges Mwyaf osodwyd yn Osodiadau Cyfrif, felly dim ond y llinellau cyntaf sydd wedi cael eu llwytho i lawr o'r gweinydd e-bost.
+
+# Partial Message Not Downloaded
+## @name MIME_MSG_PARTIAL_NOT_DOWNLOADED
+## @loc
+MIME_MSG_PARTIAL_NOT_DOWNLOADED=Heb ei Lwytho i Lawr
+
+# Partial Message Not Downloaded Explanation
+## @name MIME_MSG_PARTIAL_NOT_DOWNLOADED_EXPLANATION
+## @loc
+MIME_MSG_PARTIAL_NOT_DOWNLOADED_EXPLANATION=Dim ond penynnau'r neges yma gafodd eu llwytho i lawr o'r gweinydd e-bost.
+
+# MIME_MSG_PARTIAL_CLICK_FOR_REST
+## @name MIME_MSG_PARTIAL_CLICK_FOR_REST
+## @loc
+MIME_MSG_PARTIAL_CLICK_FOR_REST=Llwytho i lawr gweddill y neges.
diff --git a/l10n-cy/mail/chrome/messenger/mimeheader.properties b/l10n-cy/mail/chrome/messenger/mimeheader.properties
new file mode 100644
index 0000000000..44e193e3d4
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/mimeheader.properties
@@ -0,0 +1,35 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by libmime for header display in XML & HTML
+#
+TO=At
+BCC=BCC
+CC=CC
+DATE=Dyddiad
+DISTRIBUTION=Dosbarthu
+FCC=FCC
+FOLLOWUP-TO=Dilyn-At
+FROM=Oddi wrth
+STATUS=Statws
+LINES=Llinellau
+MESSAGE-ID=Neges-Enw
+MIME-VERSION=MIME-Fersiwn
+NEWSGROUPS=Grwpiau Newyddion
+ORGANIZATION=Corff
+REFERENCES=Cyfeirnodau
+REPLY-TO=Ateb-At
+RESENT-COMMENTS=Ailanfonwyd-Sylwadau
+RESENT-DATE=Ailanfonwyd-Dyddiad
+RESENT-FROM=Ailanfonwyd-Oddi wrth
+RESENT-MESSAGE-ID=Ailanfonwyd-Neges-Enw
+RESENT-SENDER=Ailanfonwyd-Anfonwr
+RESENT-TO=Ailanfonwyd-At
+RESENT-CC=Ailanfonwyd-CC
+SENDER=Anfonwr
+SUBJECT=Pwnc
+APPROVED-BY=Cymeradwywyd-Gan
+USER-AGENT=Asiant-Defnyddiwr
+FILENAME=Enw ffeil
diff --git a/l10n-cy/mail/chrome/messenger/morkImportMsgs.properties b/l10n-cy/mail/chrome/messenger/morkImportMsgs.properties
new file mode 100644
index 0000000000..d3ea8d0c73
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/morkImportMsgs.properties
@@ -0,0 +1,18 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the Mork import code to display status/error
+# and informational messages.
+#
+
+MABFiles = Llyfrau Cyfeiriadau Mork
+
+# Short name of import module
+morkImportName = Cronfa ddata Mork (.mab)
+
+# Description of import module
+morkImportDescription = Mewnforio llyfr cyfeiriadau o SeaMonkey neu fersiynau cynharach o Thunderbird.
+
+morkImportSuccess = Llwyddiant!
diff --git a/l10n-cy/mail/chrome/messenger/msgAccountCentral.dtd b/l10n-cy/mail/chrome/messenger/msgAccountCentral.dtd
new file mode 100644
index 0000000000..6361fd6cec
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/msgAccountCentral.dtd
@@ -0,0 +1,26 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY emailSectionHdr.label        "E-bost">
+<!ENTITY readMsgsLink.label           "Darllen negeseuon">
+<!ENTITY composeMsgLink.label         "Ysgrifennu neges newydd">
+
+<!ENTITY newsSectionHdr.label         "Grwpiau Newyddion">
+<!ENTITY subscribeNewsLink.label      "Rheoli tanysgrifiadau grwpiau newyddion">
+
+<!ENTITY feedsSectionHdr.label        "Llif">
+<!ENTITY subscribeFeeds.label         "Rheoli tanysgrifiadau">
+
+<!ENTITY chat.label                   "Sgwrs">
+
+<!ENTITY accountsSectionHdr.label     "Cyfrifon">
+<!ENTITY subscribeImapFolders.label   "Rheoli tanysgrifiadau ffolderi">
+<!ENTITY settingsLink.label           "Edrych ar osodiadau'r cyfrif">
+<!ENTITY setupNewAcct.label           "Gosod cyfrif:">
+
+<!ENTITY advFeaturesSectionHdr.label  "Nodweddion Uwch">
+<!ENTITY searchMsgsLink.label         "Chwilio negeseuon">
+<!ENTITY filtersLink.label            "Rheoli hidlau negeseuon">
+<!ENTITY junkSettings.label           "Gosodiadau sbam">
+<!ENTITY offlineLink.label            "Gosodiadau all-lein">
diff --git a/l10n-cy/mail/chrome/messenger/msgHdrViewOverlay.dtd b/l10n-cy/mail/chrome/messenger/msgHdrViewOverlay.dtd
new file mode 100644
index 0000000000..824f70087d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/msgHdrViewOverlay.dtd
@@ -0,0 +1,114 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY toField4.label "At">
+<!ENTITY fromField4.label "Oddi wrth">
+<!ENTITY senderField4.label "Anfonwr">
+<!ENTITY author.label "Awdur">
+<!ENTITY organizationField4.label "Corff">
+<!ENTITY replyToField4.label "Ateb i">
+
+<!ENTITY subjectField4.label "Pwnc">
+<!ENTITY ccField4.label "Cc">
+<!ENTITY bccField4.label "Bcc">
+<!ENTITY newsgroupsField4.label "Grwpiau Newyddion">
+<!ENTITY followupToField4.label "Ymateb">
+<!ENTITY tagsHdr4.label "Tagiau">
+<!ENTITY dateField4.label "Dyddiad">
+<!ENTITY userAgentField4.label "Asiant defnyddiwr">
+<!ENTITY referencesField4.label "Cyfeiriadau">
+<!ENTITY messageIdField4.label "Enw Neges">
+<!ENTITY inReplyToField4.label "Wrth ateb i">
+<!ENTITY originalWebsite4.label "Gwefan">
+
+<!ENTITY hdrArchiveButton1.label "Archifo">
+<!ENTITY hdrArchiveButton1.tooltip "Archifo'r neges">
+<!ENTITY hdrSmartReplyButton1.label "Ateb Clyfar">
+<!ENTITY hdrReplyButton1.label "Ateb">
+<!ENTITY hdrReplyButton2.tooltip "Ateb i anfonwr y neges">
+<!ENTITY hdrReplyAllButton1.label "Ateb Pawb">
+<!ENTITY hdrReplyAllButton1.tooltip "Ateb yr anfonwr a phob derbyniwr">
+<!ENTITY hdrReplyListButton1.label "Ateb i'r Rhestr">
+<!ENTITY hdrReplyListButton1.tooltip "Ateb i'r rhestr e-bost">
+<!ENTITY hdrFollowupButton1.label "Dilyn">
+<!ENTITY hdrFollowupButton1.tooltip "Gosod cofnod dilynol i'r grŵp newyddion">
+<!ENTITY hdrForwardButton1.label "Ymlaen">
+<!ENTITY hdrForwardButton1.tooltip "Anfon y neges ymlaen">
+<!ENTITY hdrJunkButton1.label "Sbam">
+<!ENTITY hdrJunkButton1.tooltip "Nodi'r neges fel sbam">
+<!ENTITY hdrTrashButton1.label "Dileu">
+<!ENTITY hdrTrashButton1.tooltip "Dileu'r neges">
+
+<!ENTITY hdrViewToolbarShowFull.label "Dangos Eiconau a Thestun">
+<!ENTITY hdrViewToolbarShowFull.accesskey "E">
+<!ENTITY hdrViewToolbarShowIcons.label "Dangos Eiconau yn Unig">
+<!ENTITY hdrViewToolbarShowIcons.accesskey "U">
+<!ENTITY hdrViewToolbarShowText.label "Dangos Testun yn Unig">
+<!ENTITY hdrViewToolbarShowText.accesskey "U">
+<!ENTITY hdrViewToolbarAlwaysReplySender.label "Dangos Ateb i Anfonwr Bob Tro">
+<!ENTITY hdrViewToolbarAlwaysReplySender.accesskey "B">
+
+<!ENTITY otherActionsButton2.label "Rhagor">
+<!ENTITY otherActionsButton.tooltip "Rhagor o weithredoedd">
+<!ENTITY otherActionsOpenConversation1.label "Agor mewn Sgwrs">
+<!ENTITY otherActionsOpenConversation1.accesskey "S">
+<!ENTITY otherActionsOpenInNewWindow1.label "Agor Ffenestr Newydd">
+<!ENTITY otherActionsOpenInNewWindow1.accesskey "F">
+<!ENTITY otherActionsOpenInNewTab1.label "Agor mewn Tab Newydd">
+<!ENTITY otherActionsOpenInNewTab1.accesskey "T">
+<!ENTITY markAsReadMenuItem1.label "Marcio wedi Darllen">
+<!ENTITY markAsReadMenuItem1.accesskey "D">
+<!ENTITY markAsUnreadMenuItem1.label "Marcio heb Ddarllen">
+<!ENTITY markAsUnreadMenuItem1.accesskey "D">
+<!ENTITY saveAsMenuItem1.label "Cadw fel…">
+<!ENTITY saveAsMenuItem1.accesskey "C">
+<!ENTITY viewSourceMenuItem1.label "Gweld y Ffynhonell">
+<!ENTITY viewSourceMenuItem1.accesskey "F">
+<!ENTITY otherActionsPrint1.label "Argraffu…">
+<!ENTITY otherActionsPrint1.accesskey "A">
+
+<!-- Attachment bar context menu items -->
+<!ENTITY startExpandedCmd.label    "Dangos y Paen Atodiad yn Gyntaf">
+<!ENTITY startExpandedCmd.accesskey    "D">
+
+<!-- Attachment context menu items -->
+<!ENTITY openAttachmentCmd.label    "Agor">
+<!ENTITY openAttachmentCmd.accesskey    "o">
+<!ENTITY saveAsAttachmentCmd.label    "Cadw Fel…">
+<!ENTITY saveAsAttachmentCmd.accesskey    "C">
+<!ENTITY detachAttachmentCmd.label    "Datod…">
+<!ENTITY detachAttachmentCmd.accesskey    "D">
+<!ENTITY deleteAttachmentCmd.label    "Dileu">
+<!ENTITY deleteAttachmentCmd.accesskey    "l">
+<!ENTITY openAllAttachmentsCmd.label    "Agor Popeth…">
+<!ENTITY openAllAttachmentsCmd.accesskey    "A">
+<!ENTITY saveAllAttachmentsCmd.label    "Cadw Popeth…">
+<!ENTITY saveAllAttachmentsCmd.accesskey    "P">
+<!ENTITY detachAllAttachmentsCmd.label    "Datod Popeth…">
+<!ENTITY detachAllAttachmentsCmd.accesskey    "a">
+<!ENTITY deleteAllAttachmentsCmd.label    "Dileu Popeth…">
+<!ENTITY deleteAllAttachmentsCmd.accesskey    "i">
+
+<!ENTITY openAttachment.tooltip "Agor y ffeil atodol">
+
+<!ENTITY detachedAttachmentFolder.show.label        "Agor Ffolder Cynhwysol">
+<!ENTITY detachedAttachmentFolder.show.accesskey    "F">
+<!ENTITY detachedAttachmentFolder.showMac.label     "Dangos yn y Canfyddwr">
+<!ENTITY detachedAttachmentFolder.showMac.accesskey "C">
+
+<!-- Attachment toolbar items -->
+<!ENTITY saveAttachmentButton1.label       "Cadw">
+<!ENTITY saveAttachmentButton1.tooltip     "Cadw'r ffeil atodol">
+<!ENTITY saveAllAttachmentsButton1.label   "Cadw Pob Un">
+<!ENTITY saveAllAttachmentsButton1.tooltip "Cadw'r holl ffeiliau atodol">
+
+<!ENTITY copyLinkCmd.label        "Copïo Lleoliad Dolen">
+<!ENTITY copyLinkCmd.accesskey    "C">
+
+<!ENTITY CopyMessageId.label "Cadw Neges-Dynodiad">
+<!ENTITY CopyMessageId.accesskey "N">
+<!ENTITY OpenMessageForMsgId.label "Agor Neges ar gyfer Enw">
+<!ENTITY OpenMessageForMsgId.accesskey "A">
+<!ENTITY OpenBrowserWithMsgId.label "Agor Porwr gyda Neges-Dynodiad">
+<!ENTITY OpenBrowserWithMsgId.accesskey "P">
diff --git a/l10n-cy/mail/chrome/messenger/msgSynchronize.dtd b/l10n-cy/mail/chrome/messenger/msgSynchronize.dtd
new file mode 100644
index 0000000000..419fba268d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/msgSynchronize.dtd
@@ -0,0 +1,27 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- extracted from MsgSynchronize.xul and msgSelectOffline.xul-->
+
+
+<!-- extracted from MsgSynchronize.xul and msgSelectOfflineFolders.xul-->
+
+<!-- extracted from MsgSynchronize.xhtml and msgSelectOfflineFolders.xhtml-->
+
+<!ENTITY MsgSynchronize.label "Llwytho i Lawr a Chydweddu Negeseuon">
+<!ENTITY MsgSelect.label "Eitemau ar Gyfer Defnydd All-lein">
+<!ENTITY MsgSyncDesc.label "Os ydych eisoes wedi dewis ffolderi e-bost neu grwpiau newyddion ar gyfer defnydd all-lein, mae modd i chi eu llwytho neu cydweddu nhw nawr. Yn lle hynny, defnyddiwch y botwm &quot;Dewis&quot; i ddewis ffolderi e-bost neu grwpiau newyddion ar gyfer defnydd all-lein.">
+<!ENTITY MsgSyncDirections.label "Llwytho i lawr a/neu gydweddu'r canlynol:">
+<!ENTITY syncTypeMail.label "Negeseuon e-bost">
+<!ENTITY syncTypeMail.accesskey "e">
+<!ENTITY syncTypeNews.label "Negeseuon grŵp newyddion">
+<!ENTITY syncTypeNews.accesskey "g">
+<!ENTITY sendMessage.label "Anfon negeseuon sydd heb eu Hanfon">
+<!ENTITY sendMessage.accesskey "A">
+<!ENTITY workOffline.label "Gweithio all-lein pan fydd y llwytho i lawr/cydweddiad wedi gorffen">
+<!ENTITY workOffline.accesskey "G">
+<!ENTITY selectButton.label "Dewis…">
+<!ENTITY selectButton.accesskey "e">
+<!ENTITY MsgSelectDesc.label "Dewiswch y ffolderi e-bost a grwpiau newyddion ar gyfer defnydd all-lein.">
+<!ENTITY MsgSelectInd.label "Llwytho i Lawr">
+<!ENTITY MsgSelectItems.label "Ffolderi a Grwpiau Newyddion">
diff --git a/l10n-cy/mail/chrome/messenger/msgViewPickerOverlay.dtd b/l10n-cy/mail/chrome/messenger/msgViewPickerOverlay.dtd
new file mode 100644
index 0000000000..17b1fb377c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/msgViewPickerOverlay.dtd
@@ -0,0 +1,23 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!--LOCALIZATION NOTE msgViewPickerOverlay.dtd UI for showing various views on a folder -->
+
+
+<!ENTITY viewPicker.label "Golwg:">
+<!ENTITY viewPicker.accesskey "l">
+<!ENTITY viewAll.label "Popeth">
+<!ENTITY viewAll.accesskey "P">
+<!ENTITY viewUnread.label "Heb eu Darllen">
+<!ENTITY viewUnread.accesskey "H">
+<!ENTITY viewNotDeleted.label "Heb ei Ddileu">
+<!ENTITY viewNotDeleted.accesskey "e">
+<!ENTITY viewTags.label "Tagiau">
+<!ENTITY viewTags.accesskey "T">
+<!ENTITY viewCustomViews.label "Golwg Cyfaddas">
+<!ENTITY viewCustomViews.accesskey "G">
+<!ENTITY viewVirtualFolder.label "Cadw Golwg fel Ffolder…">
+<!ENTITY viewVirtualFolder.accesskey "F">
+<!ENTITY viewCustomizeView.label "Cyfaddasu…">
+<!ENTITY viewCustomizeView.accesskey "C">
diff --git a/l10n-cy/mail/chrome/messenger/msgmdn.properties b/l10n-cy/mail/chrome/messenger/msgmdn.properties
new file mode 100644
index 0000000000..01b99ca3ea
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/msgmdn.properties
@@ -0,0 +1,18 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+## Msg Mdn Report strings
+MsgMdnDisplayed=Nodyn: Mae'r Dderbynneb Dychwelyd yn cydnabod bod y neges wedi ymddangos ar gyfrifiadur y derbynnydd. Nid oes gwarant fod y derbynnydd wedi darllen na deall cynnwys y neges.
+MsgMdnDispatched=Cafodd y neges ei hargraffu, ffacsio neu anfon ymlaen heb gael ei dangos i'r derbynnydd. Nid oes gwarant y bydd y derbynnydd yn darllen y neges yn diweddarach.
+MsgMdnProcessed=Cafodd y neges ei phrosesu gan raglen e-bost y derbynnydd heb ei dangos. Nid oes gwarant y bydd y derbynnydd yn darllen y neges yn ddiweddarach.
+MsgMdnDeleted=Mae'r neges wedi ei dileu. Ansicrwydd os yw'r derbynnydd wedi'i darllen neu beidio. Efallai byddant yn ei dad-dileu a'i darllen yn ddiweddarach rhywbryd.
+MsgMdnDenied=Nid yw derbynnydd y neges am anfon derbynneb derbyn yn ôl atoch chi.
+MsgMdnFailed=Digwyddodd gwall. Nid oedd modd creu nag anfon derbynneb dychwelyd dilys i chi.
+# LOCALIZATION NOTE : Do not translate the word "%S" below.
+MsgMdnMsgSentTo=Dyma Dderbynneb Dychwelyd am e-bost anfonwyd at %S.
+MdnDisplayedReceipt=Derbynneb Dychwelyd (dangos)
+MdnDispatchedReceipt=Derbynneb Dychwelyd (anfonwyd)
+MdnProcessedReceipt=Derbynneb Dychwelyd (prosesu)
+MdnDeletedReceipt=Derbynneb Dychwelyd (dileu)
+MdnDeniedReceipt=Derbynneb Dychwelyd (gwrthod)
+MdnFailedReceipt=Derbynneb Dychwelyd (methiant)
diff --git a/l10n-cy/mail/chrome/messenger/multimessageview.dtd b/l10n-cy/mail/chrome/messenger/multimessageview.dtd
new file mode 100644
index 0000000000..1e83dd68eb
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/multimessageview.dtd
@@ -0,0 +1,8 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY window.title             "Crynodeb Neges">
+<!ENTITY selectedmessages.label   "Negeseuon wedi'u Dewis">
+<!ENTITY archiveButton.label      "Archifo">
+<!ENTITY deleteButton.label       "Dileu">
diff --git a/l10n-cy/mail/chrome/messenger/multimessageview.properties b/l10n-cy/mail/chrome/messenger/multimessageview.properties
new file mode 100644
index 0000000000..829b46a509
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/multimessageview.properties
@@ -0,0 +1,66 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (numConversations): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# The number of conversations (threads or solitary messages) selected. #1 is the
+# number of conversations.
+numConversations=Dim trafodaethau; #1 trafodaeth; #1 drafodaeth; #1 trafodaeth; #1 thrafodaeth; #1 trafodaeth
+
+# LOCALIZATION NOTE (atLeastNumConversations): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# The number of conversations (threads or solitary messages) selected. #1 is the
+# number of conversations. We use this when we didn't actually scan the entire
+# list of selected messages, so there may be more conversations than reported
+# (or maybe not!).
+atLeastNumConversations=Dim trafodaethau; #1+ trafodaeth; #1+ trafodaeth; #1+ trafodaeth; #1+ trafodaeth; #1+ trafodaeth
+
+# LOCALIZATION NOTE (numMessages): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# The number of messages in a thread. #1 is the number of messages.
+numMessages=Dim negeseuon;#1 neges;#1 neges;#1 neges;#1 neges;#1 neges
+
+# LOCALIZATION NOTE (numUnread): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# The number of unread messages in a thread; meant to be appended to
+# "numMessages". #1 is the number of unread messages.
+numUnread=, dim heb eu darllen;, #1 heb ei darllen;, #1 heb eu darllen;, #1 heb eu darllen;, #1 heb eu darllen;, #1 heb eu darllen
+
+# LOCALIZATION NOTE (numIgnored): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# The number of ignored messages in a thread; meant to be appended to
+# "numMessages". #1 is the number of ignored messages.
+numIgnored=, Peidio anwybyddu;Anwybyddu #1;Anwybyddu #1;Anwybyddu #1;Anwybyddu #1;Anwybyddu #1
+
+# LOCALIZATION NOTE (atLeastNumIgnored): Semi-colon list of plural forms.
+# See: https://developer.mozilla.org/en/Localization_and_Plurals
+# The number of ignored messages in a thread; meant to be appended to
+# "numMessages". #1 is the number of ignored messages. We use this when we
+# didn't actually scan the entire list of selected messages, so there may be
+# more ignored messages than reported (or maybe not!).
+atLeastNumIgnored=, Peidio anwybyddu;, #1+ anwybyddwyd;, #1+ anwybyddwyd;, #1+ anwybyddwyd;, #1+ anwybyddwyd;, #1+ anwybyddwyd
+
+# LOCALIZATION NOTE (noSubject): What to display for a message if it has no
+# subject.
+noSubject=(dim pwnc)
+
+# LOCALIZATION NOTE (messagesTotalSize): A message indicating the total size on
+# disk of the selected messages. #1 is the size, e.g. "123 KB".
+messagesTotalSize=Mae'r negeseuon yn cymryd #1 o le.
+
+# LOCALIZATION NOTE (messagesTotalSizeMoreThan): A message indicating the total
+# size on disk of the selected messages. #1 is the size, e.g. "123 KB". We use
+# this when we didn't actually scan the entire list of selected messages, so
+# this is a *minimum* size.
+messagesTotalSizeMoreThan=Mae'r negeseuon yma'n cymryd mwy na #1 o le.
+
+# LOCALIZATION NOTE (maxCountExceeded): A message to let the user know that not
+# all of the selected messages were summarized. #1 is the total number of
+# messages selected and #2 is the number of messages actually shown.
+maxCountExceeded= (Sylwch: #1 neges wedi'u dewis, mae'r #2 cyntaf yn cael eu dangos)
+
+# LOCALIZATION NOTE (maxThreadCountExceeded): A message to let the user know that
+# not all of the selected thread were summarized. #1 is the total number of
+# threads selected and #2 is the number of threads actually shown.
+maxThreadCountExceeded= (Nodyn: #1 trywydd wedi'u dewis, #2 cyntaf yn cael eu dewis)
diff --git a/l10n-cy/mail/chrome/messenger/newFolderDialog.dtd b/l10n-cy/mail/chrome/messenger/newFolderDialog.dtd
new file mode 100644
index 0000000000..3686b6f68a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/newFolderDialog.dtd
@@ -0,0 +1,16 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- Labels -->
+   
+<!ENTITY newFolderDialog.title      "Ffolder Newydd">
+<!ENTITY name.label                 "Enw:">
+<!ENTITY name.accesskey             "E">
+<!ENTITY description.label          "Creu fel is-ffolder o:">
+<!ENTITY description.accesskey      "C">
+<!ENTITY folderRestriction1.label   "Mae'r gweinydd yn cyfyngu ffolderi i ddau fath arbennig.">
+<!ENTITY folderRestriction2.label   "Caniatáu eich ffolderi newydd i gynnwys:">
+<!ENTITY foldersOnly.label          "Ffolderi yn Unig">
+<!ENTITY messagesOnly.label         "Negeseuon yn Unig">
+<!ENTITY accept.label               "Creu Ffolder">
+<!ENTITY accept.accesskey           "r">
diff --git a/l10n-cy/mail/chrome/messenger/news.properties b/l10n-cy/mail/chrome/messenger/news.properties
new file mode 100644
index 0000000000..6d3f1227c2
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/news.properties
@@ -0,0 +1,56 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+downloadHeadersTitlePrefix=Llwytho Penynnau i Lawr
+downloadHeadersInfoText=Mae yna %S pennawd neges newydd i'w llwytho i lawr ar gyfer y grŵp newyddion yma.
+cancelDisallowed=Nid yw'r neges yn ymddangos ei fod yn dod oddi wrthych chi.  Mae modd i chi ddiddymu eich cofnodion eich hun yn unig, nid rhai wnaed gan eraill.
+cancelConfirm=Ydych chi'n siŵr eich bod am ddiddymu'r neges?
+messageCancelled=Diddymwyd y neges.
+enterUserPassTitle=Mae Angen Enw Defnyddiwr a Chyfrinair Gweinydd Newyddion
+# LOCALIZATION NOTE (enterUserPassServer): %S is the server being accessed
+enterUserPassServer=Rhowch enw defnyddiwr a chyfrinair ar gyfer: %S:
+# LOCALIZATION NOTE (enterUserPassGroup): %1$S is a specific newsgroup to set
+# the password for; %2$S is the server from which the newsgroup is accessed
+enterUserPassGroup=Rhowch enw defnyddiwr a chyfrinair ar gyfer %1$S ar %2$S:
+okButtonText=Llwytho i Lawr
+
+noNewMessages=Does dim negeseuon newydd ar y gweinydd.
+# LOCALIZATION NOTE (newNewsgroupHeaders): %1$S is the number of the current
+# header being downloaded, %2$S is the number of headers to be downloaded, and
+#  %3$S is the newsgroup whose headers are being downloaded.
+newNewsgroupHeaders=Yn llwytho i lawr %1$S o benawdau %2$S ar gyfer %3$S
+# LOCALIZATION NOTE (newNewsgroupFilteringHeaders): %1$S is the name of the MIME
+# header being filtered on, %2$S is the number of the current header being
+# downloaded, %3$S is the number of headers to be downloaded, and %4$S is the
+# newsgroup whose headers are being downloaded.
+newNewsgroupFilteringHeaders=Estyn penynnau ar gyfer hidlau: %1$S (%2$S/%3$S) ar %4$S
+downloadingArticles=Yn llwytho erthyglau %S-%S i lawr
+bytesReceived=Llwytho Grwpiau Newyddion: %S derbyniwyd (darllen %SKB ar %SKB/eil)
+downloadingArticlesForOffline=Yn llwytho erthyglau %S-%S i lawr yn %S
+
+# LOCALIZATION NOTE (autoUnsubscribeText): %1$S is the newsgroup and %2$S is the newsgroup-server it is being removed from.
+autoUnsubscribeText=Nid yw'n ymddangos fod grŵp newyddion %1$S yn bodoli ar y gwestai %2$S.  Hoffech chi ddad-danysgrifio?
+
+# LOCALIZATION NOTE (autoSubscribeText): %1$S is the newsgroup.
+autoSubscribeText=Hoffech chi danysgrifio i %1$S?
+
+# LOCALIZATION NOTE (Error -304): In the following item, don't translate "NNTP"
+# Error - server error
+## @name NNTP_ERROR_MESSAGE
+## @loc None
+-304=Digwyddodd gwall Newyddion (NNTP): \u0020
+
+# Error - newsgroup scan error
+## @name NNTP_NEWSGROUP_SCAN_ERROR
+## @loc None
+-305=Digwyddodd gwall Newyddion.  Mae'r archwiliad o'r holl grwpiau newyddion yn anghyflawn.  Ceisiwch Edrych ar yr Holl Grwpiau newyddion eto
+
+# Error - NNTP authinfo failure
+## @name NNTP_AUTH_FAILED
+## @loc None
+-260=Digwyddodd gwall caniatâd.  Ceisiwch gynnig eich enw a/neu eich cyfrinair eto.
+
+# Error - TCP error
+## @name TCP_ERROR
+## @loc None
+-206=Digwyddodd gwall cyfathrebu.  Ceisiwch gysylltu eto.  Gwall TCP:
diff --git a/l10n-cy/mail/chrome/messenger/newsError.dtd b/l10n-cy/mail/chrome/messenger/newsError.dtd
new file mode 100644
index 0000000000..562dc2e297
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/newsError.dtd
@@ -0,0 +1,31 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<!-- LOCALIZATION NOTE (newsError.title): The title of the news error page.
+     Not generally visible. -->
+
+<!ENTITY newsError.title "Anhawster Llwytho Erthygl">
+<!-- LOCALIZATION NOTE (articleNotFound.title): The main heading for the news
+     error page. -->
+
+<!ENTITY articleNotFound.title "Heb ganfod erthygl">
+<!-- LOCALIZATION NOTE (articleNotFound.desc): A longer description for the news
+     error page. -->
+
+<!ENTITY articleNotFound.desc "Mae y grwp gweinydd newyddion yn adrodd nad yw'n gallu canfod yr erthygl.">
+<!-- LOCALIZATION NOTE (serverResponded.title): A string preceding the text
+     response from the newsgroup server describing the error. -->
+
+<!ENTITY serverResponded.title "Ymateb gweinydd y grwp newyddion yw:">
+<!-- LOCALIZATION NOTE (articleExpired.title): A string explaining that the
+     article may have expired. -->
+
+<!ENTITY articleExpired.title "Efallai fod yr erthygl wedi dod i ben?">
+<!-- LOCALIZATION NOTE (trySearching.title): A string preceding the message's
+     ID. -->
+
+<!ENTITY trySearching.title "Ceisio chwilio am yr erthygl:">
+<!-- LOCALIZATION NOTE (removeExpiredArticles.title): The label for the button
+     to remove all expired articles from the newsgroup. -->
+
+<!ENTITY removeExpiredArticles.title "Tynnu'r Holl Erthyglau sydd wedi dod i Ben">
diff --git a/l10n-cy/mail/chrome/messenger/offline.properties b/l10n-cy/mail/chrome/messenger/offline.properties
new file mode 100644
index 0000000000..e0a35839ba
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/offline.properties
@@ -0,0 +1,28 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Download Messages Prompt
+downloadMessagesWindowTitle1=Llwytho Negeseuon i Lawr
+downloadMessagesLabel1=Hoffech chi lwytho negeseuon i lawr ar gyfer defnydd all-lein cyn mynd all-lein?
+downloadMessagesCheckboxLabel1=Gofyn pob tro fyddaf yn mynd all-lein
+downloadMessagesNow2=&Llwytho i Lawr Nawr
+
+# Send Messages Prompt
+sendMessagesWindowTitle1=Negeseuon heb eu Hanfon
+sendMessagesLabel2=Hoffech chi anfon y negeseuon sydd heb eu hanfon?
+sendMessagesCheckboxLabel1=Gofyn pob tro cyn i mi fynd ar-lein
+sendMessagesNow2=&Anfon Nawr
+
+processMessagesLater2=&Hwyrach
+
+# GetMessages While Offline Prompt
+getMessagesOfflineWindowTitle1=Estyn Negeseuon
+getMessagesOfflineLabel1=Rydych all-lein. Hoffech chi fynd ar-lein i estyn negeseuon newydd?
+
+# Send Messages Offline Prompt
+sendMessagesOfflineWindowTitle1=Negeseuon heb eu Hanfon
+sendMessagesOfflineLabel1=Rydych all-lein ar hyn o bryd. Hoffech chi fynd ar-lein ac anfon negeseuon sydd heb eu hanfon?
+
+offlineTooltip=Rydych all-lein.
+onlineTooltip=Rydych ar-lein.
diff --git a/l10n-cy/mail/chrome/messenger/offlineStartup.properties b/l10n-cy/mail/chrome/messenger/offlineStartup.properties
new file mode 100644
index 0000000000..ca05774262
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/offlineStartup.properties
@@ -0,0 +1,8 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+title=Gweithio Ar-lein
+desc=Hoffech chi fynd ar-lein?\n\n(Os hoffech weithio all-lein, mae'n bosib mynd ar-lein yn ddiweddarach -dewiswch 'All-lein' o'r ddewislen 'Ffeil', yna dad -dicio 'Gweithio All-lein'.)
+workOnline=Gweithio Ar-lein
+workOffline=Gweithio All-lein
diff --git a/l10n-cy/mail/chrome/messenger/outlookImportMsgs.properties b/l10n-cy/mail/chrome/messenger/outlookImportMsgs.properties
new file mode 100644
index 0000000000..7bd7824b75
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/outlookImportMsgs.properties
@@ -0,0 +1,82 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the outlook express import code to display status/error 
+# and informational messages
+#
+
+#
+# The following are used by the outlook express import code to display status/error
+# and informational messages
+#
+
+#
+# The following are used by the Outlook import code to display status/error
+# and informational messages
+#
+
+# Short name of import module
+## @name OUTLOOKIMPORT_NAME
+## @loc None
+## LOCALIZATION NOTE (2000): DONT_TRANSLATE
+2000=Outlook
+
+# Description of import module
+## @name OUTLOOKIMPORT_DESCRIPTION
+## @loc None
+## LOCALIZATION NOTE (2010): In this item, don't translate "Outlook"
+2010=E-bost a llyfrau cyfeiriadau Outlook
+
+# Success message
+## @name OUTLOOKIMPORT_MAILBOX_SUCCESS
+## @loc None
+## LOCALIZATION NOTE (2002): In this item, don't translate "%S" or "%d"
+## The variable %S will receive the name of the mailbox
+## The variable %d will receive the number of messages
+2002=Blwch e-bost %S, mewnforiwyd %d neges
+
+# Error message
+## @name OUTLOOKIMPORT_MAILBOX_BADPARAM
+## @loc None
+2003=Paramedr gwallus wedi'i basio i flwch e-bost mewnforio.
+
+# Error message
+## @name OUTLOOKIMPORT_MAILBOX_CONVERTERROR
+## @loc None
+## LOCALIZATION NOTE (2004): In this item, don't translate "%S"
+## The variable %S will receive the name of the mailbox
+2004=Gwall wrth fewnforio blwch e-bost %S, efallai na fydd yr holl negeseuon yn cael eu mewnforio o'r blwch e-bost.
+
+# Address book name
+## @name OUTLOOKIMPORT_ADDRNAME
+## @loc None
+## LOCALIZATION NOTE (2005): In this item, don't translate "Outlook"
+2005=Llyfrau cyfeiriadau Outlook
+
+# Description
+## @name OUTLOOKIMPORT_ADDRESS_SUCCESS
+## @loc None
+## LOCALIZATION NOTE (2006): In this item, don't translate "%S"
+## The variable %S will receive the name of the address book
+2006=Mewnforiwyd llyfr cyfeiriadau %S
+
+# Error message
+## @name OUTLOOKIMPORT_ADDRESS_BADPARAM
+## @loc None
+2007=Trosglwyddwyd paramedrau gwallus i'r llyfr cyfeiriadau mewnforio.
+
+# Error message
+## @name OUTLOOKIMPORT_ADDRESS_BADSOURCEFILE
+## @loc None
+## LOCALIZATION NOTE (2008): In this item, don't translate "%S"
+## The variable %S will receive the name of the address book
+2008=Gwall wrth gael mynediad ar gyfer llyfr cyfeiriadau %S.
+
+# Error message
+## @name OUTLOOKIMPORT_ADDRESS_CONVERTERROR
+## @loc None
+## LOCALIZATION NOTE (2009): In this item, don't translate "%S"
+## The variable %S will receive the name of the address book
+2009=Gwall wrth fewnforio llyfr cyfeiriadau %S, efallai nad yw'r holl gyfeiriadau wedi'u mewnforio.
diff --git a/l10n-cy/mail/chrome/messenger/pgpmime.properties b/l10n-cy/mail/chrome/messenger/pgpmime.properties
new file mode 100644
index 0000000000..e60b6a0d15
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/pgpmime.properties
@@ -0,0 +1,10 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the pgpmime content type handler
+#
+
+# LOCALIZATION NOTE(pgpMimeNeedsAddon): The text can contain HTML tags.
+pgpNotAvailable=Neges OpenPGP wedi'i hamgryptio yw hon, ond nid oes cefnogaeth ar gyfer dadgryptio OpenPGP ar gael.
diff --git a/l10n-cy/mail/chrome/messenger/preferences/applicationManager.properties b/l10n-cy/mail/chrome/messenger/preferences/applicationManager.properties
new file mode 100644
index 0000000000..4f566cf64b
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/preferences/applicationManager.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE
+# in descriptionApplications, %S will be replaced by one of the 3 following strings
+descriptionApplications=Mae modd defnyddio'r rhaglenni canlynol i drin %S.
+
+handleProtocol=%S dolen
+handleFile=Cynnwys %S
+
+descriptionWebApp=Mae'r rhaglen gwe yma wedi'i gweini yn:
+descriptionLocalApp=Mae'r rhaglen wedi'i lleoli yn:
diff --git a/l10n-cy/mail/chrome/messenger/preferences/applications.properties b/l10n-cy/mail/chrome/messenger/preferences/applications.properties
new file mode 100644
index 0000000000..ff84d06f03
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/preferences/applications.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE (dialog_removeAccount):
+# %S will be replaced with the user-defined name of a storage account.
+dialog_removeAccount=Ydych chi'n siŵr eich bod am ddiddymu'r cyfrif "%S"?
+
+# LOCALIZATION NOTE (addProvider):
+# %S will be replace with the display name of a provider, e.g. DropBox
+addProvider=Ychwanegu %S
+
+notConfiguredYet=Nid yw'r cyfrif hwn wedi'i ffurfweddu eto
diff --git a/l10n-cy/mail/chrome/messenger/preferences/messagestyle.properties b/l10n-cy/mail/chrome/messenger/preferences/messagestyle.properties
new file mode 100644
index 0000000000..16460e1b1a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/preferences/messagestyle.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Content of preview conversation for chat message styles
+default=Rhagosodedig
+nick1=Florian
+buddy1=florian@im.instantbird.org
+nick2=Patrick
+buddy2=patrick@im.instantbird.org
+message1=Helo! :-)
+message2=Be sy'n digwydd?
+message3=Rwy'n profi Thunderbird! ;-)
diff --git a/l10n-cy/mail/chrome/messenger/preferences/preferences.properties b/l10n-cy/mail/chrome/messenger/preferences/preferences.properties
new file mode 100644
index 0000000000..a886796cb9
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/preferences/preferences.properties
@@ -0,0 +1,100 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#### Junk
+confirmResetJunkTrainingTitle=Cadarnhau
+confirmResetJunkTrainingText=Ydych chi'n siŵr eich bod eisiau ailosod data hyfforddi'r hidl addasol?
+
+#### Downloads
+desktopFolderName=Bwrdd Gwaith
+myDownloadsFolderName=Fy Llwythi
+chooseAttachmentsFolderTitle=Dewis Ffolder
+
+#### Applications
+
+fileEnding=Ffeil %S
+saveFile=Cadw Ffeil
+
+# LOCALIZATION NOTE (useApp, useDefault): %S = Application name
+useApp=Defnyddio %S
+useDefault=Defnyddio %S (rhagosodiad)
+
+useOtherApp=Defnyddio arall…
+fpTitleChooseApp=Dewis Rhaglen Gynorthwyol
+manageApp=Manylion y Rhaglen…
+alwaysAsk=Gofyn bob tro
+delete=Gweithred Dileu
+confirmDeleteTitle=Gweithred Dileu
+confirmDeleteText=Ydych chi'n siŵr eich bod eisiau dileu'r weithred?
+
+# LOCALIZATION NOTE (typeDescriptionWithDetails):
+# %1$S = type description (for example "Portable Document Format")
+# %2$S = details (see below, for example "(application/pdf: .pdf, .pdfx)")
+typeDescriptionWithDetails=%1$S %2$S
+
+# LOCALIZATION NOTE (typeDetailsWithTypeOrExt):
+# %1$S = type or extensions (for example "application/pdf", or ".pdf, .pdfx")
+typeDetailsWithTypeOrExt=(%1$S)
+
+# LOCALIZATION NOTE (typeDetailsWithTypeAndExt):
+# %1$S = type (for example "application/pdf")
+# %2$S = extensions (for example ".pdf, .pdfx")
+typeDetailsWithTypeAndExt=(%1$S: %2$S)
+
+#### Sound Notifications
+soundFilePickerTitle=Dewis Sain
+
+#### Remote content
+imagepermissionstext=Mae modd i chi bennu pa ddelweddau gwefannau a chynnwys pell eraill sy'n cael caniatâd i'w llwytho. Mae hefyd modd i chi ganiatáu'r holl gynnwys pell yn seiliedig ar gyfeiriad e-bost yr anfonwr. Teipiwch gyfeiriad y wefan neu e-bost rydych am ei rheoli ac yna chlicio Rhwystro neu Caniatáu.
+imagepermissionstitle=Eithriadau - Cynnwys Pell
+
+#### Cookies
+cookiepermissionstitle=Eithriadau - Cwcis
+cookiepermissionstext=Gallwch nodi pa wefannau sy'n cael defnyddio cwcis.  Teipiwch union gyfeiriad y wefan rydych am ei ganiatáu ac yna cliciwch Rhwystro, Caniatáu am y Sesiwn neu Caniatáu.
+
+#### Cookie Viewer
+hostColon=Gwesteiwr:
+domainColon=Parth:
+forSecureOnly=Cysylltiadau wedi'u hamgryptio'n unig
+forAnyConnection=Unrhyw fath o gysylltiad
+expireAtEndOfSession=Ar ddiwedd sesiwn
+
+noCookieSelected=<heb ddewis cwci>
+cookiesAll=Mae'r cwcis canlynol wedi'u storio ar eich cyfrifiadur:
+cookiesFiltered=Mae'r cwcis canlynol yn cyd-fynd â'r chwilio:
+# LOCALIZATION NOTE (removeSelectedCookies):
+# Semicolon-separated list of plural forms. See:
+# https://developer.mozilla.org/en/docs/Localization_and_Plurals
+# If you need to display the number of selected elements in your language,
+# you can use #1 in your localization as a placeholder for the number.
+# For example this is the English string with numbers:
+# removeSelectedCookies=Remove #1 Selected;Remove #1 Selected
+removeSelectedCookies=Peidio tynnu'r dewisiadau;Tynnu'r dewis;Tynnu'r dewis;Tynnu'r dewis;Tynnu'r dewis;Tynnu'r dewis
+defaultUserContextLabel=Dim
+
+####Preferences::Advanced::Network
+#LOCALIZATION NOTE: The next string is for the disk usage of the cache.
+#   e.g., "Your cache is currently using 200 MB"
+#   %1$S = size
+#   %2$S = unit (MB, KB, etc.)
+actualDiskCacheSize=Mae eich storfa yn defnyddio %1$S %2$S o le ar ddisg
+actualDiskCacheSizeCalculated=Cyfrifo maint y storfa…
+
+# LOCALIZATION NOTE (labelDefaultFont): %S = font name
+labelDefaultFont=Rhagosodiad (%S)
+labelDefaultFontUnnamed=Rhagosodiad
+
+# LOCALIZATION NOTE (appLocale.label): %S = Name of the application locale,
+# e.g. English (United States)
+appLocale.label=Locale rhaglen: %S
+appLocale.accesskey=r
+# LOCALIZATION NOTE (rsLocale.label): %S = Name of the locale chosen in regional settings,
+# e.g. German (Germany)
+rsLocale.label=Gosodiadau rhanbarthol locale: %S
+rsLocale.accesskey=r
+
+applications-type-pdf = Portable Document Format (PDF)
+
+# LOCALIZATION NOTE (previewInApp): %S = brandShortName
+previewInApp=Rhagolwg yn %S
diff --git a/l10n-cy/mail/chrome/messenger/prefs.properties b/l10n-cy/mail/chrome/messenger/prefs.properties
new file mode 100644
index 0000000000..af2482f569
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/prefs.properties
@@ -0,0 +1,90 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The following are used by the Account Wizard
+#
+enterValidEmail=Rhowch gyfeiriad e-bost dilys.
+accountNameExists=Mae cyfrif gyda'r enw hwnnw'n bodoli eisoes. Rhowch enw arall arno.
+accountNameEmpty=Nid oes modd i enw'r cyfrif fod yn wag.
+modifiedAccountExists=Mae cyfrif gyda'r enw defnyddiwr ac enw gweinydd hynny'n bodoli eisoes. Rhowch enw defnyddiwr a/neu enw gweinydd gwahanol.
+userNameChanged=Mae eich Enw Defnyddiwr wedi'i ddiweddaru. Mae'n bosibl bod angen i chi ddiweddaru'r Cyfeiriad E-bost a/neu Enw Defnyddiwr sy'n gysylltiedig.
+serverNameChanged=Mae gosodiadau enw'r gweinydd wedi newid. Gwiriwch fod unrhyw ffolderi sy'n cael eu defnyddio gan hidlau'n bodoli ar y gweinydd newydd.
+# LOCALIZATION NOTE (junkSettingsBroken): %1$S is the account name
+junkSettingsBroken=O bosib mae gan osodiadau sbam ar gyfrif "%1$S" anhawster. Hoffech chi eu hadolygu cyn cadw Gosodiadau Cyfrif?
+# LOCALIZATION NOTE (localDirectoryChanged): %1$S is program name (&brandShortName;)
+localDirectoryChanged=Mae %1$S angen ailgychwyn er mwyn gosod y newidiadau i osodiadau'r cyfeiriadur Lleol.
+localDirectoryRestart=Ailgychwyn
+userNameEmpty=Nid oes modd i'r enw defnyddiwr fod yn wag.
+# LOCALIZATION NOTE (localDirectoryInvalid): %1$S is path to folder
+localDirectoryInvalid=Mae'r llwybr Cyfeiriadur Lleol "%1$S" yn annilys. Dewiswch gyfeiriadur arall.
+# LOCALIZATION NOTE (localDirectoryNotAllowed): %1$S is path to folder
+localDirectoryNotAllowed=Nid yw llwybr Cyfeiriadur Lleol "%1$S" yn addas ar gyfer storio negeseuon. Dewiswch gyfeiriadur arall.
+# if the user chooses to cancel the wizard when no accounts are there throw a message
+# LOCALIZATION NOTE (cancelWizard)
+# do not localize "\n\n"
+cancelWizard=Ydych chi'n siŵr eich bod am adael y Dewin Cyfrif?\n\n Os ydych yn gadael bydd unrhyw wybodaeth rydych wedi'i gynnig yn cael ei golli ac ni fydd y cyfrif yn cael ei greu.
+accountWizard=Dewin Cyfrif
+WizardExit=Gadael
+WizardContinue=Diddymu
+# when the wizard already has a domain (Should we say something different?)
+enterValidServerName=Rhowch enw gweinydd dilys.
+failedRemoveAccount=Methu dileu'r cyfrif.
+#LOCALIZATION NOTE: accountName: %1$S is server name, %2$S is user name
+accountName=%1$S - %2$S
+
+# LOCALIZATION NOTE: confirmDeferAccountWarning: do not localize "\n\n", it means a new empty line in the string.
+confirmDeferAccountWarning=Os ydych yn cadw e-bost newydd y cyfrif mewn Blwch Derbyn cyfrif gwahanol, ni fydd modd i chi gael mynediad at e-byst y cyfrif hwn sydd eisoes wedi eu llwytho i lawr. Os oes gennych e-byst yn y cyfrif hwn, copïwch nhw i gyfrif arall yn gyntaf.\n\nOs oes gennych hidlau sy'n hidlo e-bost i'r cyfrif hwn, dylech eu hanalluogi neu newid y ffolder targed. Os oes gan unrhyw gyfrif ffolderi arbennig yn y cyfrif hwn (Anfonwyd, Drafftiau, Templedi, Archifau, Sbam) dylech eu newid i gyfrif arall.\n\n A ydych dal eisiau cadw e-bost y cyfrif mewn cyfrif gwahanol?
+confirmDeferAccountTitle=Gohirio'r Cyfrif?
+
+directoryAlreadyUsedByOtherAccount=Mae cyfeiriadur rhiant y cyfeiriadur pennwyd yn y gosodiad Cyfeiriadur Lleol eisoes yn cael ei ddefnyddio gan y cyfrif "%S". Dewiswch gyfeiriadur arall.
+directoryParentUsedByOtherAccount=Mae cyfeiriadur rhiant y cyfeiriadur pennwyd yn y gosodiad Cyfeiriadur Lleol eisoes yn cael ei ddefnyddio gan y cyfrif "%S". Dewiswch gyfeiriadur arall.
+directoryChildUsedByOtherAccount=Mae is-gyfeiriadur y cyfeiriadur pennwyd yn y gosodiad Cyfeiriadur Lleol eisoes yn cael ei ddefnyddio gan y cyfrif "%S". Dewiswch gyfeiriadur arall.
+#Provide default example values for sample email address
+exampleEmailUserName=defnyddiwr
+exampleEmailDomain=esiampl.net
+emailFieldText=Cyfeiriad E-bost:
+#LOCALIZATION NOTE: defaultEmailText: %1$S is user name, %2$S is domain
+defaultEmailText=Rhowch eich cyfeiriad e-bost. Hwn fydd y cyfeiriad bydd eraill yn anfon e-bost atoch (e.e, "%1$S@%2$S").\u0020
+#LOCALIZATION NOTE: customizedEmailText: %1$S is provider, %2$S is email username, %3$S is sample email, %4$S is sample username
+customizedEmailText=Rhowch eich %1$S%2$S (er enghraifft, os mai "%3$S" yw eich cyfrif e-bost %1$S, yna %2$S yw eich "%4$S").\u0020
+
+# account manager stuff
+prefPanel-server=Gosodiadau'r Gweinydd
+prefPanel-copies=Copïau a Ffolderi
+prefPanel-synchronization=Cydweddu a Storio
+prefPanel-diskspace=Lle ar Ddisg
+prefPanel-addressing=Ysgrifennu a Chyfeirio
+prefPanel-junk=Gosodiadau Sbam
+## LOCALIZATION NOTE (prefPanel-smtp): Don't translate "SMTP"
+prefPanel-smtp=Gweinydd Anfon (SMTP)
+
+# account manager multiple identity support
+#LOCALIZATION NOTE: accountName: %1$S
+identity-list-title=Enwau ar gyfer %1$S
+
+identityDialogTitleAdd=Hunaniaeth Newydd
+## LOCALIZATION NOTE (identityDialogTitleEdit): %S is the identity name
+identityDialogTitleEdit=Golygu %S
+
+identity-edit-req=Rhaid enwi cyfeiriad e-bost dilys ar gyfer yr enw hwn.
+identity-edit-req-title=Gwall wrth Greu Enw
+
+## LOCALIZATION NOTE (identity-delete-confirm): %S is the identity name
+# and should be put on a new line. The new line is produced with the "\n" string.
+identity-delete-confirm=Ydych chi'n siŵr eich bod eisiau dileu'r hunaniaeth\n%S?
+## LOCALIZATION NOTE (identity-delete-confirm-title): %S is the account name
+identity-delete-confirm-title=Dileu hunaniaeth %S
+identity-delete-confirm-button=Dileu
+
+choosefile=Dewis ffeil
+
+forAccount=Ar gyfer cyfrif "%S"
+
+removeFromServerTitle=Cadarnhau dileu negeseuon yn awtomatig, yn barhaol
+removeFromServer=Bydd y gosodiad hwn yn dileu yn barhaol hen negeseuon o weinydd pell A'CH storfa leol. Ydych chi'n siŵr eich bod am barhau?
+
+confirmSyncChangesTitle=Cadarnhau newidiadau cydweddu
+confirmSyncChanges=Mae gosodiadau Cydweddu Neges wedi eu newid.\n\nHoffech chi eu cadw?
+confirmSyncChangesDiscard=Dileu
+
diff --git a/l10n-cy/mail/chrome/messenger/quickFilterBar.dtd b/l10n-cy/mail/chrome/messenger/quickFilterBar.dtd
new file mode 100644
index 0000000000..129e7b73c5
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/quickFilterBar.dtd
@@ -0,0 +1,269 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- LOCALIZATION NOTE (quickFilterBar.toggleBarVisibility.menu.label):
+     The label to display for the "View... Toolbars..." menu item that controls
+     whether the quick filter bar is visible.
+     -->
+<!ENTITY quickFilterBar.toggleBarVisibility.menu.label
+         "Bar Hidlo Cyflym">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.toggleBarVisibility.menu.accesskey):
+     The access key for the "View... Toolbars..." menu item label that controls
+     whether the quick filter bar is visible.
+     -->
+<!ENTITY quickFilterBar.toggleBarVisibility.menu.accesskey
+         "H">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.toggleBarVisibility.appmenu.label):
+     The label to display for the "App Menu... Preferences..." menu item that
+     controls whether the quick filter bar is visible.
+     -->
+<!ENTITY quickFilterBar.toggleBarVisibility.appmenu.label
+         "Bar Hidlo Cyflym">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.toggleBarVisibility.button.tooltip):
+     The tooltip to display when hovering over the button on the tab bar that
+     toggles the visibility of the quick filter bar.
+     -->
+<!ENTITY quickFilterBar.toggleBarVisibility.button.tooltip
+         "Toglo'r bar hidlo cyflym">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.sticky.tooltip):
+     The tooltip to display when the user hovers over the sticky button
+     (currently displayed as a push-pin).  When active, the sticky button
+     causes the current filter settings to be retained when the user changes
+     folders or opens new tabs.  (When inactive, only the state of the text
+     filters are propagated between folder changes and when opening new tabs.)
+     -->
+<!ENTITY quickFilterBar.sticky.tooltip
+         "Cadw hidlau ar waith wrth newid ffolderi">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.unread.label):
+     The label for the filter button that causes us to filter results to only
+     include unread messages.
+     -->
+<!ENTITY quickFilterBar.unread.label
+         "Heb eu Darllen">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.unread.tooltip):
+     The tooltip for the filter button that causes us to filter results to only
+     include unread messages.
+     -->
+<!ENTITY quickFilterBar.unread.tooltip
+         "Dangos negeseuon heb eu darllen yn unig">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.starred.label):
+     The label for the filter button that causes us to filter results to only
+     include messages that have been starred/flagged.
+     -->
+<!ENTITY quickFilterBar.starred.label
+         "Serennog">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.starred.tooltip):
+     The tooltip for the filter button that causes us to filter results to only
+     include messages that have been starred/flagged.
+     -->
+<!ENTITY quickFilterBar.starred.tooltip
+         "Dangos dim ond negeseuon serennog">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.inaddrbook.label):
+     The label for the filter button that causes us to filter results to only
+     include messages from contacts in one of the user's non-remote address
+     books.
+     -->
+<!ENTITY quickFilterBar.inaddrbook.label
+         "Cysylltiad">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.inaddrbook.tooltip):
+     The tooltip for the filter button that causes us to filter results to only
+     include messages from contacts in one of the user's non-remote address
+     books.
+     -->
+<!ENTITY quickFilterBar.inaddrbook.tooltip
+         "Dangos dim ond negeseuon gan bobl yn eich llyfr cyfeiriadau">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.tags.label):
+     The label for the filter button that causes us to filter results to only
+     include messages with at least one tag on them.
+     -->
+<!ENTITY quickFilterBar.tags.label
+         "Tagiau">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.tags.tooltip):
+     The tooltip for the filter button that causes us to filter results to only
+     include messages with at least one tag on them.
+     -->
+<!ENTITY quickFilterBar.tags.tooltip
+         "Dangos dim ond negeseuon gyda thagiau">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.attachment.label):
+     The label for the filter button that causes us to filter results to only
+     include messages with attachments.
+     -->
+<!ENTITY quickFilterBar.attachment.label
+         "Atodiad">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.attachment.tooltip):
+     The tooltip for the filter button that causes us to filter results to only
+     include messages with attachments.
+     -->
+<!ENTITY quickFilterBar.attachment.tooltip
+         "Dangos dim ond negeseuon gydag atodiadau">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.resultsLabel.some.formatString):
+     This is used to populate the results box; it either displays the
+     number of messages found using this string, that there are no messages
+     (using quickFilterBar.resultsLabel.none), or the box is hidden.
+     This is a pluralizable string used to express the number of messages in
+     the results.  We replace the '#1' with the number of messages, otherwise
+     see the following URL For more information:
+     https://developer.mozilla.org/En/Localization_and_Plurals
+     -->
+<!ENTITY quickFilterBar.resultsLabel.some.formatString
+         "Dim negeseuon;#1 neges;#1 neges;#1 neges;#1 neges;#1 neges">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.resultsLabel.none):
+     The contents of the results box when there is a filter active but there
+     are no messages matching the filter.
+     -->
+<!ENTITY quickFilterBar.resultsLabel.none
+         "Dim canlyniadau">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.resultsLabel.minWidth):
+     The minimum width, in pixels, of the results label.  Please size this
+     so that a 3 or 4 digit number of messages in the results can be displayed
+     without growing the size of the box.  You can tell this has been
+     accomplished if adding a filter constraint that changes the displayed
+     string to your "no results" string does not result in any changes to the
+     size of the text box to the label's right.  (If your string for
+     "no results" is longer than the "#### messages" case, then size for that.
+     -->
+<!ENTITY quickFilterBar.resultsLabel.minWidth
+         "100">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textbox.emptyText.base1):
+     This is the base of the empty text for the text search box.  We replace
+     #1 with the contents of the appropriate
+     quickFilterBar.textbox.emptyText.keyLabel.* value for the platform.
+     The goal is to convey to the user that typing in the box will filter
+     the messages and that there is a hotkey they can press to get to the
+     box faster.
+     -->
+<!ENTITY quickFilterBar.textbox.emptyText.base1
+         "Hidlo'r negeseuon hyn #1">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.show.key2):
+     This is the key used to show the quick filter bar. -->
+<!ENTITY quickFilterBar.show.key2
+         "k">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textbox.emptyText.keyLabel.nonmac):
+     The description of the key-binding to get into the box on windows and
+     linux (which use the control key).  This should match the value of
+     quickFilterBar.show.key above.
+     -->
+<!ENTITY quickFilterBar.textbox.emptyText.keyLabel2.nonmac
+         "&lt;Ctrl+Shift+K&gt;">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textbox.emptyText.keyLabel.mac):
+     The description of the key-binding to get into the box on mac systems.
+     This should match the value of quickFilterBar.show.key above.
+     -->
+<!ENTITY quickFilterBar.textbox.emptyText.keyLabel2.mac
+         "&lt;&#x21E7;&#x2318;K&gt;">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.booleanMode.tooltip):
+     Tooltip of the Any of / All of tagging mode selector.
+     -->
+<!ENTITY quickFilterBar.booleanMode.tooltip "Modd hidlo tagiau">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.booleanModeAny.label):
+     Tooltip of the Any of / All of tagging mode selector.
+     -->
+<!ENTITY quickFilterBar.booleanModeAny.label "Unrhyw un o">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.booleanModeAny.tooltip):
+     Tooltip of the Any of / All of tagging mode selector.
+     -->
+<!ENTITY quickFilterBar.booleanModeAny.tooltip "Dylai o leiaf un o'r meini prawf tag hyn gydweddu">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.booleanModeAll.label):
+     Tooltip of the Any of / All of tagging mode selector.
+     -->
+<!ENTITY quickFilterBar.booleanModeAll.label "Pob un">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.booleanModeAll.tooltip):
+     Tooltip of the Any of / All of tagging mode selector.
+     -->
+<!ENTITY quickFilterBar.booleanModeAll.tooltip "Dylai pob un o'r meini prawf tag hyn gydweddu">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textbox.idealWidth):
+     The number of pixels for the ideal width of the quick filter box textbox.
+     Choose this value so that the emptyText fits nicely with a little bit of
+     extra whitespace.
+     -->
+<!ENTITY quickFilterBar.textbox.idealWidth
+         "320">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textbox.minWidth):
+     The minimum width of the quick filter textbox in pixels.  This is the size
+     which we should refuse to flex below.  When we hit this size, the buttons
+     with labels will have their labels collapsed.
+     -->
+<!ENTITY quickFilterBar.textbox.minWidth
+         "280">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textFilter.explanation.label):
+     This label explains what the sender/recipients/subject/body buttons do.
+     This string should ideally be kept short because the label and the text
+     filter buttons share their bar (that appears when there is text in the text
+     filter box) with the list of tags when the tag filter is active, and the
+     tag sub-bar wants as much space as possible.  (Overflow is handled by an
+     arrow scroll box.)
+     -->
+<!ENTITY quickFilterBar.textFilter.explanation.label
+         "Hidlo negeseuon yn ôl:">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textFilter.sender.label):
+     The button label that toggles whether the text filter searches the message
+     sender for the string.
+     -->
+<!ENTITY quickFilterBar.textFilter.sender.label
+         "Anfonwr">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textFilter.recipients.label):
+     The button label that toggles whether the text filter searches the message
+     recipients (to, cc) for the string.
+     -->
+<!ENTITY quickFilterBar.textFilter.recipients.label
+         "Derbynwyr">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textFilter.subject.label):
+     The button label that toggles whether the text filter searches the message
+     subject for the string.
+     -->
+<!ENTITY quickFilterBar.textFilter.subject.label
+         "Pwnc">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.textFilter.body.label):
+     The button label that toggles whether the text filter searches the message
+     body for the string.
+     -->
+<!ENTITY quickFilterBar.textFilter.body.label
+         "Corff">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.glodaUpsell.continueSearch):
+     The first line of the panel popup that tells the user we found no matches
+     but we can convert to a global search for them.
+     -->
+<!ENTITY quickFilterBar.glodaUpsell.continueSearch
+         "Parhau i chwilio pob ffolder">
+
+<!-- LOCALIZATION NOTE (quickFilterBar.glodaUpsell.pressEnterAndCurrent):
+     The second line of the panel popup that tells the user we found no matches.
+     This line will have #1 replaced with what the user has typed so far.
+     -->
+<!ENTITY quickFilterBar.glodaUpsell.pressEnterAndCurrent
+         "Pwyswch 'Enter' eto i barhau i chwilio am: #1">
diff --git a/l10n-cy/mail/chrome/messenger/removeAccount.dtd b/l10n-cy/mail/chrome/messenger/removeAccount.dtd
new file mode 100644
index 0000000000..063af3c957
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/removeAccount.dtd
@@ -0,0 +1,22 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY dialogTitle                  "Tynnu Cyfrif a Data">
+<!ENTITY removeButton.label           "Tynnu">
+<!ENTITY removeButton.accesskey       "T">
+<!ENTITY removeAccount.label          "Tynnu manylion cyfrif">
+<!ENTITY removeAccount.accesskey      "c">
+<!ENTITY removeAccount.desc           "Bydd yn tynnu gwybodaeth &brandShortName; am y cyfrif hwn, yn unig. Nid yw'n effeithio ar y cyfrif ei hun ar y gweinydd.">
+<!ENTITY removeData.label             "Tynnu data negeseuon">
+<!ENTITY removeData.accesskey         "d">
+<!ENTITY removeDataChat.label         "Tynnu data sgwrs">
+<!ENTITY removeDataChat.accesskey     "s">
+<!ENTITY removeDataLocalAccount.desc  "Bydd yn tynnu'r holl negeseuon, ffolderi a hidlau sy'n gysylltiedig â'r cyfrif hwn o'ch disg lleol. Nid yw hyn yn effeithio ar rhai negeseuon sy'n cael eu cadw ar y gweinydd. Peidiwch â dewis hwn os ydych yn bwriadu archifo'r data lleol neu ei ailddefnyddio yn ddiweddarach o fewn &brandShortName;.">
+<!ENTITY removeDataServerAccount.desc "Bydd yn tynnu'r holl negeseuon, ffolderi a hidlau sy'n gysylltiedig â'r cyfrif hwn o'ch disg. Bydd eich negeseuon a'ch ffolderi yn cael eu cadw ar y gweinydd.">
+<!ENTITY removeDataChatAccount.desc   "Yn tynnu pob cofnod o sgyrsiau sydd wedi eu cadw ar gyfer y cyfrif hwn ar eich disg lleol.">
+<!ENTITY showData.label               "Dangos lleoliad y data">
+<!ENTITY showData.accesskey           "l">
+<!ENTITY progressPending              "Tynnu data penodol…">
+<!ENTITY progressSuccess              "Llwyddodd y tynnu.">
+<!ENTITY progressFailure              "Methodd y tynnu.">
diff --git a/l10n-cy/mail/chrome/messenger/removeAccount.properties b/l10n-cy/mail/chrome/messenger/removeAccount.properties
new file mode 100644
index 0000000000..04d2fbf3aa
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/removeAccount.properties
@@ -0,0 +1,5 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+removeQuestion=Ydych chi'n siŵr eich bod am dynnu'r cyfrif "%S"?
diff --git a/l10n-cy/mail/chrome/messenger/renameFolderDialog.dtd b/l10n-cy/mail/chrome/messenger/renameFolderDialog.dtd
new file mode 100644
index 0000000000..47beecf007
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/renameFolderDialog.dtd
@@ -0,0 +1,9 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+   
+<!ENTITY renameFolderDialog.title          "Ailenwi'r Ffolder">
+<!ENTITY rename.label                      "Rhowch enw newydd i'ch ffolder:">
+<!ENTITY rename.accesskey                  "R">
+<!ENTITY accept.label                      "Ailenwi">
+<!ENTITY accept.accesskey                  "A">
diff --git a/l10n-cy/mail/chrome/messenger/sanitize.dtd b/l10n-cy/mail/chrome/messenger/sanitize.dtd
new file mode 100644
index 0000000000..e88ad30a73
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/sanitize.dtd
@@ -0,0 +1,36 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY sanitizeDialog2.title         "Clirio Hanes Diweddar">
+
+<!-- XXX rearrange entities to match physical layout when l10n isn't an issue -->
+<!-- LOCALIZATION NOTE (clearTimeDuration.*): "Time range to clear" dropdown.
+     See UI mockup at bug 480169 -->
+<!ENTITY clearTimeDuration.label          "Ystod amser i'w glirio: ">
+<!ENTITY clearTimeDuration.accesskey      "Y">
+<!ENTITY clearTimeDuration.lastHour       "Awr Olaf">
+<!ENTITY clearTimeDuration.last2Hours     "Dwy Awr Olaf">
+<!ENTITY clearTimeDuration.last4Hours     "Pedair Awr Olaf">
+<!ENTITY clearTimeDuration.today          "Heddiw">
+<!ENTITY clearTimeDuration.everything     "Popeth">
+<!-- Localization note (clearTimeDuration.suffix) - trailing entity for languages
+that require it.  -->
+<!ENTITY clearTimeDuration.suffix         "">
+
+
+<!ENTITY historyGroup.label                "Hanes">
+
+<!ENTITY itemHistory.label                 "Hanes Pori">
+<!ENTITY itemHistory.accesskey             "H">
+<!ENTITY itemCookies.label                 "Cwcis">
+<!ENTITY itemCookies.accesskey             "C">
+<!ENTITY itemCache.label                   "Storfa">
+<!ENTITY itemCache.accesskey               "S">
+
+<!-- LOCALIZATION NOTE (sanitizeEverythingUndoWarning): Second warning paragraph
+     that appears when "Time range to clear" is set to "Everything".  See UI
+     mockup at bug 480169 -->
+<!ENTITY sanitizeEverythingUndoWarning     "Nid oes modd dadwneud y weithred.">
+
+<!ENTITY dialog.width                 "28em">
diff --git a/l10n-cy/mail/chrome/messenger/seamonkeyImportMsgs.properties b/l10n-cy/mail/chrome/messenger/seamonkeyImportMsgs.properties
new file mode 100644
index 0000000000..806c332e89
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/seamonkeyImportMsgs.properties
@@ -0,0 +1,18 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+# The following are used by the seamonkey import code to display status/error
+# and informational messages
+
+# Short name of import module
+SeamonkeyImportName=SeaMonkey
+
+# Description of import module
+SeamonkeyImportDescription=Mewnforio llyfrau cyfeiriadau, e-bost a chyfrifon o SeaMonkey.
+
+# Success Message for addressbook import
+SeamonkeyImportAddressSuccess=Mewnforiwyd llyfrau cyfeiriadau yn llwyddiannus.
+
+# Success Message for mail import
+SeamonkeyImportSettingsSuccess=Mewnforiwyd negeseuon a chyfrifon lleol yn llwyddiannus.
diff --git a/l10n-cy/mail/chrome/messenger/search-attributes.properties b/l10n-cy/mail/chrome/messenger/search-attributes.properties
new file mode 100644
index 0000000000..db5130802d
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/search-attributes.properties
@@ -0,0 +1,45 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#these need to match nsMsgSearchAttrib interface in nsMsgSearchCore.idl
+#and nsMsgSearchAttribMap in nsMsgSearchAdapter.cpp
+Subject=Pwnc
+From=Oddi wrth
+Body=Corff
+Date=Dyddiad
+Priority=Blaenoriaeth
+Status=Statws
+To=At
+Cc=Cc
+ToOrCc=To neu Cc
+AgeInDays=Oed mewn Dyddiau
+SizeKB=Maint (KB)
+Tags=Tagiau
+# for AB and LDAP
+AnyName=Unrhyw Enw
+DisplayName=Dangos Enw
+Nickname=Llysenw
+ScreenName=Enw Sgrin
+Email=E-bost
+AdditionalEmail=E-bost Ychwanegol
+AnyNumber=Unrhyw Rif
+WorkPhone=Rhif Ffôn Gwaith
+HomePhone=Rhif Ffôn Cartref
+Fax=Ffacs
+Pager=Swnyn
+Mobile=Ffôn Symudol
+City=Tref/Dinas
+Street=Stryd
+Title=Teitl
+Organization=Corff
+Department=Adran
+# more mailnews
+FromToCcOrBcc=Oddi wrth, At, Cc neu Bcc
+JunkScoreOrigin=Tarddiad Sgôr Sbam
+JunkPercent=Canran Sbam
+AttachmentStatus=Statws Atodiad
+JunkStatus=Statws Sbam
+Label=Label
+Customize=Cyfaddasu…
+MissingCustomTerm=Term Cyfaddas Coll
diff --git a/l10n-cy/mail/chrome/messenger/search-operators.properties b/l10n-cy/mail/chrome/messenger/search-operators.properties
new file mode 100644
index 0000000000..f70f751961
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/search-operators.properties
@@ -0,0 +1,31 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+0=yn cynnwys
+1=nid yw'n cynnwys
+2=yn
+3=nid yw'n
+4=yn wag
+
+5=o flaen
+6=ar ôl
+    
+7=yn uwch na
+8=yn is na
+
+9=yn cychwyn gyda
+10=yn gorffen gyda
+
+11=yn swnio fel
+12=LdapDwim
+
+13=yn fwy na
+14=yn llai na
+
+15=Cwblhau Enw
+16=yn fy llyfr cyfeiriadau
+17=nid yw yn fy llyfr cyfeiriadau
+18=nid yw'n wag
+19=yn cydweddu â
+20=nid yw'n cydweddu â
diff --git a/l10n-cy/mail/chrome/messenger/search.properties b/l10n-cy/mail/chrome/messenger/search.properties
new file mode 100644
index 0000000000..4ce66fa2ed
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/search.properties
@@ -0,0 +1,27 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# these are the fields that get inserted in the search line
+# for "and" searches, this looks like:
+#
+# searchAnd0 <attribute> searchAnd1 <operator> searchAnd2 <value> searchAnd4
+#
+# for example, in english this looks like:
+# and the [Sender ] [doesn't contain] [John]
+#
+# TODO: need to special-case the first line (filterindex==0)
+
+# filter stuff
+
+searchingMessage=Chwilio…
+# LOCALIZATION NOTE (matchesFound): #1 number of matches found
+matchesFound=wedi canfod #1 sy'n cydweddu;wedi canfod #1 sy'n cydweddu
+noMatchesFound=Heb ganfod cydweddiad
+labelForStopButton=Atal
+labelForSearchButton=Chwilio
+labelForStopButton.accesskey=A
+labelForSearchButton.accesskey=C
+
+moreButtonTooltipText=Ychwanegu rheol newydd
+lessButtonTooltipText=Tynnu'r rheol
diff --git a/l10n-cy/mail/chrome/messenger/searchTermOverlay.dtd b/l10n-cy/mail/chrome/messenger/searchTermOverlay.dtd
new file mode 100644
index 0000000000..6fa4783d85
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/searchTermOverlay.dtd
@@ -0,0 +1,19 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY matchAll.label     "Cydweddu â'r canlynol i gyd">
+<!ENTITY matchAll.accesskey "y">
+<!ENTITY matchAny.label     "Cydweddu ag unrhyw un o'r canlynol">
+<!ENTITY matchAny.accesskey "d">
+<!ENTITY matchAllMsgs.label     "Cydweddu pob neges">
+<!ENTITY matchAllMsgs.accesskey "n">
+<!-- LOCALIZATION NOTE
+  The values below are used to control the widths of the search widgets.
+  Change the values only when the localized strings in the popup menus
+  are truncated in the widgets.
+ -->
+
+<!ENTITY searchTermListAttributesFlexValue "1">
+<!ENTITY searchTermListOperatorsFlexValue "1">
+<!ENTITY searchTermListValueFlexValue "3">
diff --git a/l10n-cy/mail/chrome/messenger/shutdownWindow.properties b/l10n-cy/mail/chrome/messenger/shutdownWindow.properties
new file mode 100644
index 0000000000..2064a7f58b
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/shutdownWindow.properties
@@ -0,0 +1,10 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+# These strings are loaded and represented by the XUL dialog.
+shutdownDialogTitle=Diffodd Ffenestr Cynnydd
+taskProgress=Prosesu %1$S o %2$S o Dasgau\u0020
+
+# These strings are loaded by the individual shutdown tasks.
diff --git a/l10n-cy/mail/chrome/messenger/smime.properties b/l10n-cy/mail/chrome/messenger/smime.properties
new file mode 100644
index 0000000000..da65e4a0a0
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/smime.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the smime content type handler
+#
+
+## @name NS_MSG_UNABLE_TO_OPEN_FILE
+## LOCALIZATION NOTE: the text can contain HTML tags. 
+1000=Mae hon yn neges <B>ENCRYPTED</B> or <B>SIGNED</B>.<br> Nid yw'r rhaglen hon yn cynnal e-bost wedi ei hamgryptio na'i llofnodi.
+
+
diff --git a/l10n-cy/mail/chrome/messenger/smtpEditOverlay.dtd b/l10n-cy/mail/chrome/messenger/smtpEditOverlay.dtd
new file mode 100644
index 0000000000..4ccbc1e315
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/smtpEditOverlay.dtd
@@ -0,0 +1,24 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY settings.caption "Gosodiadau">
+<!ENTITY security.caption "Diogelwch a Dilysu">
+<!ENTITY serverName.label "Enw'r Gweinydd:">
+<!ENTITY serverName.accesskey "G">
+<!ENTITY serverDescription.label "Disgrifiad:">
+<!ENTITY serverDescription.accesskey "D">
+<!ENTITY serverPort.label "Porth:">
+<!ENTITY serverPort.accesskey "P">
+<!ENTITY userName.label "Enw Defnyddiwr:">
+<!ENTITY userName.accesskey "E">
+<!ENTITY connectionSecurity.label "Diogelwch y cysylltiad:">
+<!ENTITY connectionSecurity.accesskey "D">
+<!ENTITY connectionSecurityType-0.label "Dim">
+<!ENTITY connectionSecurityType-1.label "STARTTLS, os ar gael">
+<!ENTITY connectionSecurityType-2.label "STARTTLS">
+<!ENTITY connectionSecurityType-3.label "SSL/TLS">
+<!ENTITY smtpEditTitle.label "Gweinydd SMTP">
+<!ENTITY serverPortDefault.label "Rhagosodedig:">
+<!ENTITY authMethod.label "Dull dilysu:">
+<!ENTITY authMethod.accesskey "u">
diff --git a/l10n-cy/mail/chrome/messenger/subscribe.dtd b/l10n-cy/mail/chrome/messenger/subscribe.dtd
new file mode 100644
index 0000000000..69988a69fa
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/subscribe.dtd
@@ -0,0 +1,22 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY subscribeDialog.title        "Tanysgrifio">
+<!ENTITY subscribeButton.label        "Tanysgrifio">
+<!ENTITY subscribeButton.accesskey    "s">
+<!ENTITY unsubscribeButton.label      "Dad-danysgrifio">
+<!ENTITY unsubscribeButton.accesskey  "D">
+<!ENTITY newGroupsTab.label           "Grwpiau Newydd">
+<!ENTITY newGroupsTab.accesskey       "G">
+<!ENTITY refreshButton.label          "Adnewyddu">
+<!ENTITY refreshButton.accesskey      "A">
+<!ENTITY stopButton.label             "Atal">
+<!ENTITY stopButton.accesskey         "t">
+<!ENTITY server.label                 "Cyfrif:">
+<!ENTITY server.accesskey             "C">
+<!ENTITY subscribedHeader.label       "Tanysgrifio">
+<!-- commenting out until bug 38906 is fixed 
+<!ENTITY messagesHeader.label         "Messages"> -->
+<!ENTITY namefield.label              "Dangos eitemau sy'n cynnwys:">
+<!ENTITY namefield.accesskey          "D">
diff --git a/l10n-cy/mail/chrome/messenger/subscribe.properties b/l10n-cy/mail/chrome/messenger/subscribe.properties
new file mode 100644
index 0000000000..ace52d541b
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/subscribe.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+subscribeLabel-nntp=Dewis y grwpiau newyddion i danysgrifio iddynt:
+subscribeLabel-imap=Dangos y ffolderi i danysgrifio iddynt:
+currentListTab-nntp.label=Rhestr Grwpiau Cyfredol
+currentListTab-nntp.accesskey=C
+currentListTab-imap.label=Rhestr Ffolderi
+currentListTab-imap.accesskey=F
+pleaseWaitString=Arhoswch…
+offlineState=Rydych all-lein. Nid oedd modd estyn eitemau oddi ar y gweinydd.
+errorPopulating=Gwall wrth estyn eitemau o'r gweinydd.
diff --git a/l10n-cy/mail/chrome/messenger/tabmail.dtd b/l10n-cy/mail/chrome/messenger/tabmail.dtd
new file mode 100644
index 0000000000..ee27184cfb
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/tabmail.dtd
@@ -0,0 +1,9 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY  closeTab.label           "Cau'r Tab">
+<!ENTITY  listAllTabs.label        "Rhestru pob tab">
+<!-- LOCALIZATION NOTE(defaultTabTitle.label): This is the default tab
+     title to show when the tab has no title. -->
+<!ENTITY  defaultTabTitle.label    "Cartref">
diff --git a/l10n-cy/mail/chrome/messenger/taskbar.properties b/l10n-cy/mail/chrome/messenger/taskbar.properties
new file mode 100644
index 0000000000..21d0132743
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/taskbar.properties
@@ -0,0 +1,8 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+taskbar.tasks.composeMessage.label=Ysgrifennu neges newydd
+taskbar.tasks.composeMessage.description=Ysgrifennu neges newydd.
+taskbar.tasks.openAddressBook.label=Agor llyfr cyfeiriadau
+taskbar.tasks.openAddressBook.description=Agor eich llyfr cyfeiriadau.
diff --git a/l10n-cy/mail/chrome/messenger/telemetry.properties b/l10n-cy/mail/chrome/messenger/telemetry.properties
new file mode 100644
index 0000000000..c736bd9b66
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/telemetry.properties
@@ -0,0 +1,13 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Telemetry prompt
+# LOCALIZATION NOTE (telemetryText): %1$S will be replaced by brandFullName,
+# and %2$S by the value of the toolkit.telemetry.server_owner preference.
+telemetryText = Hoffech chi gynorthwyo i wella %1$S drwy gofnodi'n awtomatig defnydd cof, perfformiad ac ymatebolrwydd i %2$S?
+telemetryLinkLabel = Dysgu Rhagor
+telemetryYesButtonLabel = Iawn
+telemetryYesButtonAccessKey = I
+telemetryNoButtonLabel = Na
+telemetryNoButtonAccessKey = N
diff --git a/l10n-cy/mail/chrome/messenger/templateUtils.properties b/l10n-cy/mail/chrome/messenger/templateUtils.properties
new file mode 100644
index 0000000000..12e007477c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/templateUtils.properties
@@ -0,0 +1,7 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE yesterday: used in various places where we compute
+# a "friendly" date, e.g. displaying that a message was from yesterday.
+yesterday=ddoe
diff --git a/l10n-cy/mail/chrome/messenger/textImportMsgs.properties b/l10n-cy/mail/chrome/messenger/textImportMsgs.properties
new file mode 100644
index 0000000000..3d827dfe17
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/textImportMsgs.properties
@@ -0,0 +1,53 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the outlook express import code to display status/error 
+# and informational messages
+#
+
+#
+# The following are used by the outlook express import code to display status/error
+# and informational messages
+#
+
+#
+# The following are used by the text import code to display status/error
+# and informational messages
+#
+
+# Short name of import module
+## @name TEXTIMPORT_NAME
+## @loc None
+2000=Ffeil testun (LDIF, .tab, .csv, .txt)
+
+# Description of import module
+## @name TEXTIMPORT_DESCRIPTION
+## @loc None
+2001=Mewnforio llyfr cyfeiriadau o ffeil testun, gan gynnwys fformatau  LDIF (.ldif, .ldi), tab dadamffinedig (.tab, .txt) coma gwahanedig (.csv).
+
+# Description of import module
+## @name TEXTIMPORT_ADDRESS_NAME
+## @loc None
+2002=Llyfr Cyfeiriadau Testun
+
+# Description
+## @name TEXTIMPORT_ADDRESS_SUCCESS
+## @loc None
+2003=Llyfr cyfeiriadau wedi'i fewnforio %S
+
+# Error message
+## @name TEXTIMPORT_ADDRESS_BADPARAM
+## @loc None
+2004=Paramedr gwael wedi'i basio i'r llyfr cyfeiriadau.
+
+# Error message
+## @name TEXTIMPORT_ADDRESS_BADSOURCEFILE
+## @loc None
+2005=Gwall wrth gael mynediad ar gyfer llyfr cyfeiriadau %S.
+
+# Error message
+## @name TEXTIMPORT_ADDRESS_CONVERTERROR
+## @loc None
+2006=Gwall wrth fewnforio llyfr cyfeiriadau %S, efallai nad yw'r holl gyfeiriadau wedi'u mewnforio.
diff --git a/l10n-cy/mail/chrome/messenger/vCardImportMsgs.properties b/l10n-cy/mail/chrome/messenger/vCardImportMsgs.properties
new file mode 100644
index 0000000000..2ebcd34088
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/vCardImportMsgs.properties
@@ -0,0 +1,26 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the vCard import code to display status, error, and
+# informational messages
+#
+
+vCardImportName=Ffeil vCard (.vcf)
+
+vCardImportDescription=Mewnforio llyfr cyfeiriadau ar ffurf fformat vCard
+
+vCardImportAddressName=Llyfr Cyfeiriadau vCard
+
+# LOCALIZATION NOTE (vCardImportAddressSuccess): %S is replaced by the
+# name of the address book being imported.
+vCardImportAddressSuccess=Llyfr cyfeiriadau wedi'i fewnforio %S
+
+# LOCALIZATION NOTE (vCardImportAddressSuccess): %S is replaced by the
+# name of the address book being imported.
+vCardImportAddressBadSourceFile=Gwall wrth gael mynediad ar gyfer llyfr cyfeiriadau %S.
+
+# LOCALIZATION NOTE (vCardImportAddressSuccess): %S is replaced by the
+# name of the address book being imported.
+vCardImportAddressConvertError=Gwall wrth fewnforio llyfr cyfeiriadau %S, efallai nad yw'r holl gyfeiriadau wedi'u mewnforio.
diff --git a/l10n-cy/mail/chrome/messenger/viewLog.dtd b/l10n-cy/mail/chrome/messenger/viewLog.dtd
new file mode 100644
index 0000000000..05111c4d37
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/viewLog.dtd
@@ -0,0 +1,12 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY viewLog.title "Cofnod Hidl">
+<!ENTITY viewLogInfo.text "Mae'r Cofnod Hidl yn cofnodi'r hidlau sydd wedi'u rhedeg ar y cyfrif. Defnyddiwch y blwch ticio isod i alluogi cofnodi.">
+<!ENTITY clearLog.label "Clirio'r Cofnod">
+<!ENTITY clearLog.accesskey "C">
+<!ENTITY enableLog.label "Galluogi Cofnod Hidl">
+<!ENTITY enableLog.accesskey "G">
+<!ENTITY closeLog.label "Cau">
+<!ENTITY closeLog.accesskey "u">
diff --git a/l10n-cy/mail/chrome/messenger/viewSource.dtd b/l10n-cy/mail/chrome/messenger/viewSource.dtd
new file mode 100644
index 0000000000..6e31177a26
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/viewSource.dtd
@@ -0,0 +1,86 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- extracted from content/viewSource.xul -->
+
+<!-- extracted from content/viewSource.xhtml -->
+
+<!-- LOCALIZATION NOTE (mainWindow.title) : DONT_TRANSLATE -->
+<!ENTITY mainWindow.title "&brandFullName;">
+<!-- LOCALIZATION NOTE (mainWindow.titlemodifier) : DONT_TRANSLATE -->
+<!ENTITY mainWindow.titlemodifier "&brandFullName;">
+<!-- LOCALIZATION NOTE (mainWindow.titlemodifierseparator) : DONT_TRANSLATE -->
+<!ENTITY mainWindow.titlemodifierseparator " - ">
+<!ENTITY mainWindow.preface "Ffynhonnell: ">
+
+<!ENTITY editMenu.label "Golygu">
+<!ENTITY editMenu.accesskey "G">
+<!ENTITY fileMenu.label "Ffeil">
+<!ENTITY fileMenu.accesskey "F">
+<!ENTITY savePageCmd.label "Cadw Tudalen Fel…">
+<!ENTITY savePageCmd.accesskey "C">
+<!ENTITY savePageCmd.commandkey "S">
+<!ENTITY printCmd.label "Argraffu…">
+<!ENTITY printCmd.accesskey "A">
+<!ENTITY printCmd.commandkey "P">
+<!ENTITY closeCmd.label "Cau">
+<!ENTITY closeCmd.accesskey "C">
+<!ENTITY closeCmd.commandkey "W">
+
+<!-- LOCALIZATION NOTE :
+textEnlarge.commandkey3, textReduce.commandkey2 and
+textReset.commandkey2 are alternative acceleration keys for zoom.
+If shift key is needed with your locale popular keyboard for them,
+you can use these alternative items. Otherwise, their values should be empty.  -->
+
+<!ENTITY textEnlarge.commandkey "+">
+<!ENTITY textEnlarge.commandkey2 "=">
+<!ENTITY textEnlarge.commandkey3 "">
+<!ENTITY textReduce.commandkey "-">
+<!ENTITY textReduce.commandkey2 "">
+<!ENTITY textReset.commandkey "0">
+<!ENTITY textReset.commandkey2 "">
+
+<!ENTITY goToLineCmd.label "Mynd i Linell…">
+<!ENTITY goToLineCmd.accesskey "M">
+<!ENTITY goToLineCmd.commandkey "l">
+
+<!ENTITY viewMenu.label           "Golwg">
+<!ENTITY viewMenu.accesskey       "o">
+<!ENTITY reloadCmd.label "Ail-lwytho">
+<!ENTITY reloadCmd.accesskey "A">
+<!ENTITY reloadCmd.commandkey "r">
+<!ENTITY menu_wrapLongLines.title "Amlapio Llinellau Hir">
+<!ENTITY menu_wrapLongLines.accesskey "L">
+<!ENTITY menu_highlightSyntax.label "Amlygu Cystrawen">
+<!ENTITY menu_highlightSyntax.accesskey "m">
+<!ENTITY menu_textSize.label "Maint Testun">
+<!ENTITY menu_textSize.accesskey "T">
+<!ENTITY menu_textEnlarge.label "Cynyddu">
+<!ENTITY menu_textEnlarge.accesskey "y">
+<!ENTITY menu_textReduce.label "Lleihau">
+<!ENTITY menu_textReduce.accesskey "L">
+<!ENTITY menu_textReset.label "Arferol">
+<!ENTITY menu_textReset.accesskey "A">
+
+<!ENTITY findOnCmd.label     "Canfod ar y Dudalen…">
+<!ENTITY findOnCmd.accesskey "D">
+<!ENTITY findOnCmd.commandkey "f">
+<!ENTITY findAgainCmd.label  "Canfod Eto">
+<!ENTITY findAgainCmd.accesskey "E">
+<!ENTITY findAgainCmd.commandkey "g">
+<!ENTITY findAgainCmd.commandkey2 "VK_F3">
+<!ENTITY findSelectionCmd.commandkey "e">
+
+<!ENTITY backCmd.label "Nôl">
+<!ENTITY backCmd.accesskey "N">
+<!ENTITY forwardCmd.label "Ymlaen">
+<!ENTITY forwardCmd.accesskey "Y">
+<!ENTITY goBackCmd.commandKey "[">
+<!ENTITY goForwardCmd.commandKey "]">
+
+<!ENTITY copyLinkCmd.label "Copïo Lleoliad Dolen">
+<!ENTITY copyLinkCmd.accesskey "L">
+<!ENTITY copyEmailCmd.label "Copïo Cyfeiriad E-bost">
+<!ENTITY copyEmailCmd.accesskey "E">
diff --git a/l10n-cy/mail/chrome/messenger/viewSource.properties b/l10n-cy/mail/chrome/messenger/viewSource.properties
new file mode 100644
index 0000000000..60f65d960b
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/viewSource.properties
@@ -0,0 +1,17 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+goToLineTitle     = Mynd i llinell
+goToLineText      = Rhowch rif y llinell
+invalidInputTitle = Mewnbwn annilys
+invalidInputText  = Mae'r rhif roddwyd yn annilys.
+outOfRangeTitle   = Heb ganfod y llinell
+outOfRangeText    = Heb ganfod y llinell hon.
+viewSelectionSourceTitle = Ffynhonnell DOM Dewis
+viewMathMLSourceTitle    = Ffynhonnell DOM MathML
+
+context_goToLine_label        = Mynd i Llinell…
+context_goToLine_accesskey    = L
+context_wrapLongLines_label   = Amlapio Llinellau Hir
+context_highlightSyntax_label = Amlygu Cystrawen
diff --git a/l10n-cy/mail/chrome/messenger/viewZoomOverlay.dtd b/l10n-cy/mail/chrome/messenger/viewZoomOverlay.dtd
new file mode 100644
index 0000000000..f024b9ac6a
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/viewZoomOverlay.dtd
@@ -0,0 +1,32 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- LOCALIZATION NOTE :
+fullZoomEnlargeCmd.commandkey3, fullZoomReduceCmd.commandkey2 and
+fullZoomResetCmd.commandkey2 are alternative acceleration keys for zoom.
+If shift key is needed with your locale popular keyboard for them,
+you can use these alternative items. Otherwise, their values should be empty.  -->
+
+
+<!ENTITY fullZoomEnlargeCmd.label       "Chwyddo Mewn">
+<!ENTITY fullZoomEnlargeCmd.accesskey   "M">
+<!ENTITY fullZoomEnlargeCmd.commandkey  "+">
+<!-- + is above this key on many keyboards -->
+<!ENTITY fullZoomEnlargeCmd.commandkey2 "="> 
+<!ENTITY fullZoomEnlargeCmd.commandkey3 "">
+
+<!ENTITY fullZoomReduceCmd.label        "Chwyddo Allan">
+<!ENTITY fullZoomReduceCmd.accesskey    "A">
+<!ENTITY fullZoomReduceCmd.commandkey   "-">
+<!ENTITY fullZoomReduceCmd.commandkey2  "">
+
+<!ENTITY fullZoomResetCmd.label         "Ailosod">
+<!ENTITY fullZoomResetCmd.accesskey     "A">
+<!ENTITY fullZoomResetCmd.commandkey    "0">
+<!ENTITY fullZoomResetCmd.commandkey2   "">
+
+<!ENTITY fullZoomToggleCmd.label        "Chwyddo'r Testun yn Unig">
+<!ENTITY fullZoomToggleCmd.accesskey    "T">
+<!ENTITY fullZoom.label                 "Chwyddo">
+<!ENTITY fullZoom.accesskey             "C">
diff --git a/l10n-cy/mail/chrome/messenger/virtualFolderListDialog.dtd b/l10n-cy/mail/chrome/messenger/virtualFolderListDialog.dtd
new file mode 100644
index 0000000000..88bcc3b76c
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/virtualFolderListDialog.dtd
@@ -0,0 +1,10 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY virtualFolderListTitle.title        "Dewis Ffolder(i)">
+<!ENTITY virtualFolderDesc.label       "Dewis ffolderi i'w chwilio:">
+
+
+<!ENTITY folderName.label "Enw ffolder">
+<!ENTITY folderSearch.label "Chwilio">
diff --git a/l10n-cy/mail/chrome/messenger/virtualFolderProperties.dtd b/l10n-cy/mail/chrome/messenger/virtualFolderProperties.dtd
new file mode 100644
index 0000000000..4ee6e55bc3
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/virtualFolderProperties.dtd
@@ -0,0 +1,22 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY virtualFolderProperties.title "Ffolder Chwilio wedi'i Chadw Newydd">
+<!ENTITY name.label                 "Enw:">
+<!ENTITY name.accesskey             "E">
+<!ENTITY description.label          "Creu fel is-ffolder o:">
+<!ENTITY description.accesskey      "i">
+
+<!ENTITY searchTermCaption.label "Ffurfweddu'r meini prawf chwilio ar gyfer y ffolder chwilio a gadwyd: ">
+
+<!ENTITY folderSelectionCaption.label "Dewis ffolderi i'w chwilio: ">
+<!ENTITY chooseFoldersButton.label "Dewis…">
+<!ENTITY chooseFoldersButton.accesskey "D">
+
+<!ENTITY searchOnline.label "Chwilio Ar-lein (Mae'n cynnig y canlyniadau diweddaraf ar ffolderi IMAP a Newyddion ond mae'n cymryd mwy o amser i agor y ffolder)">
+<!ENTITY searchOnline.accesskey "A">
+<!ENTITY newFolderButton.label       "Creu">
+<!ENTITY newFolderButton.accesskey   "r">
+<!ENTITY editFolderButton.label      "Diweddaru">
+<!ENTITY editFolderButton.accesskey  "D">
diff --git a/l10n-cy/mail/chrome/messenger/wmImportMsgs.properties b/l10n-cy/mail/chrome/messenger/wmImportMsgs.properties
new file mode 100644
index 0000000000..649a337245
--- /dev/null
+++ b/l10n-cy/mail/chrome/messenger/wmImportMsgs.properties
@@ -0,0 +1,76 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# The following are used by the windows live mail import code to display status/error
+# and informational messages
+#
+
+# Short name of import module
+## @name WMIMPORT_NAME
+## @loc None
+## LOCALIZATION NOTE (2000): DONT_TRANSLATE
+2000=Windows Live Mail
+
+# Description of import module
+## @name WMIMPORT_DESCRIPTION
+## @loc None
+## LOCALIZATION NOTE (2001): In this item, don't translate "Windows Live Mail"
+2001=Gosodiadau Windows Live Mail
+
+# Success message
+## @name WMIMPORT_MAILBOX_SUCCESS
+## @loc None
+## LOCALIZATION NOTE (2002): In this item, don't translate "%1$S" or "%2$d"
+## The variable %1$S will contain the name of the Mailbox
+## The variable %2$d will contain the number of messages
+2002=Blwch E-bost %1$S, wedi mewnforio %2$d neges
+
+# Error message
+## @name WMIMPORT_MAILBOX_BADPARAM
+## @loc None
+2003=Paramedr gwallus wedi'i basio i flwch e-bost mewnforio.
+
+# Error message
+## @name WMIMPORT_MAILBOX_BADSOURCEFILE
+## @loc None
+## LOCALIZATION NOTE (2004): In this item, don't translate "%S"
+## The variable %S will contain the name of the Mailbox
+2004=Gwall wrth gael mynediad i flwch e-bost %S.
+
+# Error message
+## @name WMIMPORT_MAILBOX_CONVERTERROR
+## @loc None
+## LOCALIZATION NOTE (2005): In this item, don't translate "%S"
+## The variable %S will contain the name of the Mailbox
+2005=Gwall wrth fewnforio blwch e-bost %S, efallai na fydd yr holl negeseuon yn cael eu mewnforio o'r blwch e-bost.
+
+# Default name of imported addressbook
+## @name WMIMPORT_DEFAULT_NAME
+## @loc None
+2006=Llyfr Cyfeiriadau Windows Live Mail
+
+# Autofind description
+## @name WMIMPORT_AUTOFIND
+## @loc None
+2007=Llyfr cyfeiriadau Windows Live Mail (llyfr cyfeiriadau windows)
+
+# Description
+## @name WMIMPORT_ADDRESS_SUCCESS
+## @loc None
+## LOCALIZATION NOTE (2006): In this item, don't translate "%S"
+## The variable %S will receive the name of the address book
+2008=Llyfr cyfeiriadau wedi'i fewnforio %S
+
+# Error message
+## @name WMIMPORT_ADDRESS_CONVERTERROR
+## @loc None
+## LOCALIZATION NOTE (2009): In this item, don't translate "%S"
+## The variable %S will receive the name of the address book
+2009=Gwall wrth fewnforio llyfr cyfeiriadau %S, efallai nad yw'r holl gyfeiriadau wedi'u mewnforio.
+
+# Error message
+## @name WMIMPORT_ADDRESS_BADPARAM
+## @loc None
+2010=Pasiwyd paramedrau gwallus i'r llyfr cyfeiriadau sydd wedi'i fewnforio.
diff --git a/l10n-cy/mail/chrome/mozldap/ldap.properties b/l10n-cy/mail/chrome/mozldap/ldap.properties
new file mode 100644
index 0000000000..026909b197
--- /dev/null
+++ b/l10n-cy/mail/chrome/mozldap/ldap.properties
@@ -0,0 +1,272 @@
+# 
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The following two strings are used when prompting the user for authentication
+# information:
+
+## @name AUTH_PROMPT_TITLE
+## @loc none
+authPromptTitle=Angen Cyfrinair Gweinydd LDAP
+
+## @name AUTH_PROMPT_TEXT
+## @loc %1$S should not be localized.  It is the hostname of the LDAP server.
+authPromptText=Rhowch eich cyfrinair ar gyfer %1$S.
+
+# These are string versions of all the errors defined in
+# nsILDAPErrors.idl, as well as the nsresult codes based on those
+# errors.  See that file for the genesis of these codes, as well as 
+# for info about how to get documentation about their precise
+# meanings.
+
+# These are string versions of all the errors defined in
+# nsILDAPErrors.idl, as well as the nsresult codes based on those
+# errors.  See that file for the genesis of these codes, as well as
+# for info about how to get documentation about their precise
+# meanings.
+
+## @name OPERATIONS_ERROR
+## @loc none
+1=Gwall gweithredu
+
+## @name PROTOCOL_ERROR
+## @loc none
+2=Gwall protocol
+
+## @name TIMELIMIT_EXCEEDED
+## @loc none
+3=Tu hwnt i derfyn amser
+
+## @name SIZELIMIT_EXCEEDED
+## @loc none
+4=Tu hwnt i derfyn maint
+
+## @name COMPARE_FALSE
+## @loc none
+5=Cymharu gau
+
+## @name COMPARE_TRUE
+## @loc none
+6=Cymharu true
+
+## @name STRONG_AUTH_NOT_SUPPORTED
+## @loc none
+7=Nid yw'r dull dilysu'n cael ei gynnal
+
+## @name STRONG_AUTH_REQUIRED
+## @loc none
+8=Mae angen dilysiad cryf
+
+## @name PARTIAL_RESULTS
+## @loc none
+9=Wedi derbyn canlyniadau a chyfeirio rhannol
+
+## @name REFERRAL
+## @loc none
+10=Cyfeirio wedi'i dderbyn
+
+## @name ADMINLIMIT_EXCEEDED
+## @loc none
+11=Terfyn gweinyddol wedi'i groesi
+
+## @name UNAVAILABLE_CRITICAL_EXTENSION
+## @loc none
+12=Estyniad hanfodol ddim ar gael
+
+## @name CONFIDENTIALITY_REQUIRED
+## @loc none
+13=Angen cyfrinachedd
+
+## @name SASL_BIND_IN_PROGRESS
+## @loc none
+14=Rhwymiad SASL ar waith
+
+## @name NO_SUCH_ATTRIBUTE
+## @loc none
+16=Dim priodoledd o'r fath
+
+## @name UNDEFINED_TYPE
+## @loc none
+17=Math priodoledd anniffinedig
+
+## @name INAPPROPRIATE MATCHIN
+## @loc none
+18=Cydweddu anaddas
+
+## @name CONSTRAINT_VIOLATION
+## @loc none
+19=Torri ar gyfyngiad
+
+## @name TYPE_OR_VALUE_EXISTS
+## @loc none
+20=Math neu werth ar gael
+
+## @name INVALID_SYNTAX
+## @loc none
+21=Cystrawen annilys
+
+## @name NO_SUCH_OBJECT
+## @loc none
+32=Dim gwrthrych o'r fath
+
+## @name ALIAS_PROBLEM
+## @loc none
+33=Problem enw arall
+
+## @name INVALID_DN_ SYNTAX
+## @loc none
+34=Cystrawen DN annilys
+
+## @name IS_LEAF
+## @loc none
+35=Mae'r gwrthrych yn ddeilen
+
+## @name ALIAS_DEREF_PROBLEM
+## @loc none
+36=Anhawster dadgyfeirio enw arall
+
+## @name INAPPROPRIATE_AUTH
+## @loc none
+48=Dilysiad annaddas
+
+## @name INVALID_CREDENTIALS
+## @loc none
+49=Cyflwyno annilys
+
+## @name INSUFFICIENT_ACCESS
+## @loc none
+50=Mynediad annigonol
+
+## @name BUSY
+## @loc none
+51=Mae'r gweinydd LDAP yn brysur
+
+## @name UNAVAILABLE
+## @loc none
+52=Nid yw'r gweinydd LDAP ar gael
+
+## @name UNWILLING_TO_PERFORM
+## @loc none
+53=Mae'r gweinydd LDAP yn gwrthod gweithredu
+
+## @name LOOP_DETECT
+## @loc none
+54=Cylchu wedi'i ganfod
+
+## @name SORT_CONTROL_MISSING
+## @loc none
+60=Mae Rheoli Didoli ar goll
+
+## @name INDEX_RANGE_ERROR
+## @loc none
+61=Mae canlyniadau chwilio'n fwy na'r ystod sydd wedi'i bennu gan yr atredau
+
+## @name NAMING_VIOLATION
+## @loc none
+64=Trosedd enwi
+
+## @name OBJECT_CLASS_VIOLATION
+## @loc none
+65=Trosedd dosbarth gwrthrych
+
+## @name NOT_ALLOWED_ON_NONLEAF
+## @loc none
+66=Dim caniatâd i'r weithred anddeilen
+
+## @name NOT_ALLOWED_ON_RDN
+## @loc none
+67=Dim caniatâd i'r weithred ar RDN
+
+## @name ALREADY_EXISTS
+## @loc none
+68=Yn bodoli eisoes
+
+## @name NO_OBJECT_CLASS_MODS
+## @loc none
+69=Methu newid dosbarth gwrthrych
+
+## @name RESULTS_TOO_LARGE
+## @loc none
+70=Canlyniad yn rhy fawr
+
+## @name AFFECTS_MULTIPLE_DSAS
+## @loc none
+71=Effeithio ar weinyddion niferus
+
+## @name OTHER
+## @loc none
+80=Gwall anhysbys
+
+## @name SERVER_DOWN
+## @loc none
+81=Methu cysylltu â gweinydd LDAP
+
+## @name LOCAL_ERROR
+## @loc none
+82=Gwall lleol
+
+## @name ENCODING_ERROR
+## @loc none
+83=Gwall amgodio
+
+## @name DECODING_ERROR
+## @loc none
+84=Gwall dadgodio
+
+## @name TIMEOUT
+## @loc none
+85=Daeth amser y gweinydd LDAP i ben
+
+## @name AUTH_UNKNOWN
+## @loc none
+86=Dull dilysu anhysbys
+
+## @name FILTER_ERROR
+## @loc none
+87=Hidl chwilio annilys
+
+## @name USER_CANCELLED
+## @loc none
+88=Gweithred defnyddiwr wedi'i ddiddymu
+
+## @name PARAM_ERROR
+## @loc none
+89=Paramedr gwael i drefn LDAP
+
+## @name NO_MEMORY
+## @loc none
+90=Dim cof ar ôl
+
+## @name CONNECT_ERROR
+## @loc none
+91=Methu cysylltu â weinydd LDAP
+
+## @name NOT_SUPPORTED
+## @loc none
+92=Nid yw'n cael ei gynnal gan y fersiwn yma o brotocol LDAP
+
+## @name CONTROL_NOT_FOUND
+## @loc none
+93=Heb ganfod y rheolydd LDAP
+
+## @name NO_RESULTS_RETURNED
+## @loc none
+94=Heb ddychwelyd canlyniadau
+
+## @name MORE_RESULTS_TO_RETURN
+## @loc none
+95=Rhagor o ganlyniadau i'w dychwelyd
+
+## @name CLIENT_LOOP
+## @loc none
+96=Mae'r cleient wedi canfod cylchu
+
+## @name REFERRAL_LIMIT_EXCEEDED
+## @loc none
+97=Hop cyfeirio wedi mynd dros y terfyn
diff --git a/l10n-cy/mail/chrome/overrides/netError.dtd b/l10n-cy/mail/chrome/overrides/netError.dtd
new file mode 100644
index 0000000000..edbacb462a
--- /dev/null
+++ b/l10n-cy/mail/chrome/overrides/netError.dtd
@@ -0,0 +1,109 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!ENTITY % brandDTD SYSTEM "chrome://branding/locale/brand.dtd">
+%brandDTD;
+
+<!ENTITY loadError.label "Anhawster llwytho tudalen">
+<!ENTITY retry.label "Ceisio Eto">
+
+<!-- Specific error messages -->
+
+<!ENTITY connectionFailure.title "Methu cysylltu">
+<!ENTITY connectionFailure.longDesc "&sharedLongDesc;">
+
+<!ENTITY deniedPortAccess.title "Mae'r cyfeiriad wedi'i gyfyngu">
+<!ENTITY deniedPortAccess.longDesc "">
+
+<!ENTITY dnsNotFound.title "Heb ganfod gweinydd">
+<!ENTITY dnsNotFound.longDesc "<ul> <li>Gwiriwch y cyfeiriad am wallau teipio megis <strong>ww</strong>.example.com yn lle <strong>www</strong>.example.com</li> <li>Os ydych yn methu llwytho unrhyw dudalen, gwiriwch gysylltiad rhwydwaith eich cyfrifiadur.</li> <li>Os yw eich cyfrifiadur neu rwydwaith wedi ei ddiogelu gan fur cadarn neu ddirprwy gwnewch yn siŵr fod gan &brandShortName; ganiatâd i fynd ar y We.</li> </ul>">
+
+<!ENTITY fileNotFound.title "Heb ganfod ffeil">
+<!ENTITY fileNotFound.longDesc "<ul> <li>Gwiriwch yr enw ffeil am brif lythrennu neu wallau teipio eraill.</li> <li>Gwiriwch i weld os yw'r ffeil wedi symud, ailenwi neu ei dileu.</li> </ul>">
+
+<!ENTITY fileAccessDenied.title "Mae mynediad at y ffeil wedi ei wrthod">
+<!ENTITY fileAccessDenied.longDesc "<ul> <li>Gall ei fod wedi ei dynnu, symud neu fod caniatâd ffeiliau yn rhwystro mynediad.</li> </ul>">
+
+<!ENTITY generic.title "Wps.">
+<!ENTITY generic.longDesc "<p>Nid yw &brandShortName; yn gallu llwytho'r dudalen am ryw reswm.</p>">
+
+<!ENTITY malformedURI.title "Nid yw'r cyfeiriad yn ddilys">
+<!ENTITY malformedURI.longDesc "<ul> <li>Fel rheol mae cyfeiriadau Gwe'n cael eu hysgrifennu fel <strong>http://www.example.com/</strong></li> <li>Gwnewch yn siŵr eich bod yn defnyddio blaen slaes (h.y. <strong>/</strong>).</li> </ul>">
+
+<!ENTITY netInterrupt.title "Cafodd y cysylltiad ei darfu">
+<!ENTITY netInterrupt.longDesc "&sharedLongDesc;">
+
+<!ENTITY notCached.title "Daeth y Ddogfen i Ben">
+<!ENTITY notCached.longDesc "<p>Nid yw'r ddogfen hon ar gael yn y storfa.</p><ul><li>Fel cam diogelwch nid yw, &brandShortName; yn gofyn eto am ddogfennau sensitif yn awtomatig.</li><li>Cliciwch Ceisio Eto i ofyn eto am y ddogfen o'r wefan.</li></ul>">
+
+<!ENTITY netOffline.title "Modd all-lein">
+<!ENTITY netOffline.longDesc2 "<ul> <li>Clicio &quot;Ceisio newid eto&quot; i newid i&apos;r modd ar-lein ac ail lwytho'r dudalen.</li> </ul>">
+
+<!ENTITY contentEncodingError.title "Gwall amgodio cynnwys">
+<!ENTITY contentEncodingError.longDesc "<ul> <li>Cysylltwch â pherchnogion y wefan i'w hysbysu o'r anhawster.</li> </ul>">
+
+<!ENTITY unsafeContentType.title "Math ffeil anniogel">
+<!ENTITY unsafeContentType.longDesc "<ul> <li>Cysylltwch â pherchnogion y wefan i'w hysbysu o'r anhawster.</li> </ul>">
+
+<!ENTITY netReset.title "Cafodd y cysylltiad ei ailosod">
+<!ENTITY netReset.longDesc "&sharedLongDesc;">
+
+<!ENTITY netTimeout.title "Mae cyfnod y cyswllt wedi dod i ben">
+<!ENTITY netTimeout.longDesc "&sharedLongDesc;">
+
+<!ENTITY unknownProtocolFound.title "Heb ddeall y cyfeiriad">
+<!ENTITY unknownProtocolFound.longDesc "<ul> <li>Efallai bydd angen i chi osod meddalwedd arall i agor y cyfeiriad yma.</li> </ul>">
+
+<!ENTITY proxyConnectFailure.title "Mae'r gweinydd dirprwy yn gwrthod cysylltiadau">
+<!ENTITY proxyConnectFailure.longDesc "<ul> <li>Gwiriwch osodiadau'r dirprwy i wneud yn siŵr eu bod yn gywir.</li> <li>Cysylltwch â'ch gweinyddwr system i wneud yn siŵr fod y gweinydd dirprwyol yn gweithio.</li> </ul>">
+
+<!ENTITY proxyResolveFailure.title "Methu canfod y gweinydd dirprwyol">
+<!ENTITY proxyResolveFailure.longDesc "<ul> <li>Gwiriwch y gosodiadau dirprwyol i wneud yn siŵr eu bod yn gywir.</li> <li>Gwiriwch fod gan eich cyfrifiadur cyswllt a'r we sy'n gweithio.</li> <li>Os yw eich cyfrifiadur wedi ei ddiogelu gan fur cadarn neu ddirprwy, gwnewch yn siŵr fod gan &brandShortName; fynediad i'r we.</li> </ul>">
+
+<!ENTITY redirectLoop.title "Nid yw'r dudalen yn ailgyfeirio'n iawn">
+<!ENTITY redirectLoop.longDesc "<ul> <li>Gall y broblem yma fod wedi ei hachosi drwy analluogi neu wrthod cwci.</li> </ul>">
+
+<!ENTITY unknownSocketType.title "Ymateb annisgwyl gan y gweinydd">
+<!ENTITY unknownSocketType.longDesc "<ul> <li>Gwiriwch fod gan eich system Reolwr Diogelwch Personol wedi ei osod.</li> <li>Gall hyn fod oherwydd ffurfweddiad ansafonol ar y gweinydd.</li> </ul>">
+
+<!ENTITY nssFailure2.title "Methodd y cysylltiad diogel">
+<!ENTITY nssFailure2.longDesc2 "<ul> <li>Nid oes modd dangos y dudalen rydych yn ceisio ei darllen am nad oes modd dilysu'r data rydych wedi ei dderbyn.</li> <li>Cysylltwch â pherchnogion y wefan i'w hysbysu o'r anhawster.</li> </ul>">
+
+<!ENTITY nssBadCert.title "Methodd y cysylltiad diogel">
+<!ENTITY nssBadCert.longDesc2 "<ul> <li>Gall hwn fod yn anhawster gyda ffurfweddiad y gweinydd neu gall fod yn rhywun sy'n ceisio dynwared y gweinydd.</li> <li>Os ydych wedi cysylltu'n llwyddiannus gyda'r gweinydd yn y gorffennol, efallai mai gwall dros dro ydyw ac i geisio eto yn ddiweddarach.</li> </ul>">
+
+<!ENTITY sharedLongDesc "<ul> <li>Efallai bod y wefan yn brysur neu nad yw ar gael dros dro. Ceisiwch eto ymhen ychydig.</li> <li>Os nad ydych yn gallu llwytho unrhyw dudalennau, gwiriwch gysylltiad rhwydwaith eich cyfrifiadur.</li> <li>Os yw eich cyfrifiadur neu rwydwaith wedi ei ddiogelu gan fur cadarn neu ddirprwy, gwnewch yn siŵr fod gan &brandShortName; hawl i fynediad i'r we.</li> </ul>">
+
+<!ENTITY cspBlocked.title "Rhwystrwyd gan Bolisi Diogelwch Cynnwys">
+<!ENTITY cspBlocked.longDesc "<p>Mae &brandShortName; wedi rhwystro'r dudalen rhag llwytho yn y ffordd yma gan fod gan y dudalen bolisi diogelwch cynnwys sy'n atal hynny.</p>">
+
+<!ENTITY xfoBlocked.title "Wedi'i rwystro gan Bolisi X-Frame-Options">
+<!ENTITY xfoBlocked.longDesc "<p>Mae &brandShortName; wedi atal y dudalen hon rhag llwytho yn y cyd-destun hwn oherwydd bod gan y dudalen bolisi X-Frame-Options sy'n ei gwrthod.</p>">
+
+<!ENTITY corruptedContentErrorv2.title "Gwall Cynnwys Llygredig">
+<!ENTITY corruptedContentErrorv2.longDesc "<p>Nid oes modd dangos y dudalen rydych yn ceisio ei gweld yn sgil canfod gwall trosglwyddo data.</p><ul><li>Cysylltwch â pherchnogion y wefan i'w hysbysu o'r anhawster.</li></ul>">
+
+<!ENTITY securityOverride.linkText "Neu mae modd ychwanegu eithriad…">
+<!ENTITY securityOverride.getMeOutOfHereButton "Allan o fan hyn!">
+<!ENTITY securityOverride.exceptionButtonLabel "Ychwanegu Eithriad…">
+
+<!-- LOCALIZATION NOTE (securityOverride.warningContent) - Do not translate the
+contents of the <button> tags. It uses strings already defined above. The
+button is included here (instead of netError.xhtml) because it exposes
+functionality specific to thunderbird. -->
+
+<!ENTITY securityOverride.warningContent "<p>Ni ddylech ychwanegu eithriad os ydych yn defnyddio cyswllt gwe nad ydych yn ymddiried ynddo'n llwyr neu os nad ydych wedi arfer a gweld rhybudd ar y gweinydd hwn.</p>  <button id='getMeOutOfHereButton'>&securityOverride.getMeOutOfHereButton;</button> <button id='exceptionDialogButton'>&securityOverride.exceptionButtonLabel;</button>">
+
+<!ENTITY remoteXUL.title "XUL pell">
+<!ENTITY remoteXUL.longDesc "<p><ul><li>Cysylltwch â pherchnogion y wefan i'w hysbysu am y broblem..</li></ul></p>">
+
+<!ENTITY inadequateSecurityError.title "Nid yw eich cysylltiad yn ddiogel">
+<!-- LOCALIZATION NOTE (inadequateSecurityError.longDesc) - Do not translate
+     "NS_ERROR_NET_INADEQUATE_SECURITY". -->
+<!ENTITY inadequateSecurityError.longDesc "Mae <p><span class='hostname'></span> yn defnyddio technoleg diogelwch sy'n hen ac yn agored i ymosodiad. Gall yr ymosodwr weld manylion am hyn roeddech yn meddwl ei fod yn ddiogel. Mae angen i weinyddwr y wefan drwsio'r gweinydd yn gyntaf cyn bod modd i chi ymweld â' r wefan.</p><p>Cod gwall: NS_ERROR_NET_INADEQUATE_SECURITY</p>">
+
+<!ENTITY blockedByPolicy.title "Tudalen wedi ei Rhwystro">
+
+<!ENTITY networkProtocolError.title "Gwall Protocol Rhwydwaith">
+<!ENTITY networkProtocolError.longDesc "<p>Nid oes modd dangos y dudalen rydych yn ceisio'i gweld oherwydd canfuwyd gwall yn y protocol rhwydwaith.</p><ul><li>Cysylltwch â pherchenogion y wefan i roi gwybod iddynt am y broblem hon.</li></ul>">
diff --git a/l10n-cy/mail/chrome/overrides/profileDowngrade.dtd b/l10n-cy/mail/chrome/overrides/profileDowngrade.dtd
new file mode 100644
index 0000000000..11186f653d
--- /dev/null
+++ b/l10n-cy/mail/chrome/overrides/profileDowngrade.dtd
@@ -0,0 +1,20 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+
+<!-- LOCALIZATION NOTE:
+ This UI can be most easily shown by modifying the version in compatibility.ini
+ to a newer version and then starting Thunderbird.
+ For this feature, "installation" is used to mean "this discrete download of
+ Thunderbird" and "version" is used to mean "the specific revision number of a
+ given Thunderbird channel". These terms are not synonymous.
+-->
+<!ENTITY window.title "Rydych chi wedi cychwyn fersiwn hŷn o &brandProductName;">
+<!ENTITY window.style "width: 490px;">
+
+<!ENTITY window.nosync2 "Efallai fod fersiwn mwy diweddar o &brandProductName; wedi gwneud newidiadau i'ch proffil nad ydynt bellach yn gydnaws â'r fersiwn hŷn hwn. Defnyddiwch y proffil hwn yn unig gyda'r fersiwn mwy newydd hwnnw, neu crëwch broffil newydd ar gyfer y gosodiad hwn o &brandShortName;. Er mwyn creu proffil newydd mae angen gosod eich cyfrifon, calendrau a'ch ychwanegion eto.">
+
+<!ENTITY window.moreinfo "Rhagor o wybodaeth…">
+<!ENTITY window.create "Creu Proffil Newydd">
+<!ENTITY window.quit-win "Gadael">
+<!ENTITY window.quit-nonwin "Gadael">
diff --git a/l10n-cy/mail/crashreporter/crashreporter-override.ini b/l10n-cy/mail/crashreporter/crashreporter-override.ini
new file mode 100644
index 0000000000..0289df47f4
--- /dev/null
+++ b/l10n-cy/mail/crashreporter/crashreporter-override.ini
@@ -0,0 +1,9 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# This file is in the UTF-8 encoding
+[Strings]
+# LOCALIZATION NOTE (CrashReporterProductErrorText2): The %s is replaced with a string containing detailed information.
+CrashReporterProductErrorText2=Profodd Firefox anhawster a chwalodd. Byddwn yn ceisio adfer eich tabiau a ffenestri pan fydd yn ailgychwyn.\n\nYn anffodus, nid yw'r adroddwr chwalu'n gallu cyflwyno adroddiad chwalu.\n\nManylion: %s
+CrashReporterDescriptionText2=Profodd Firefox anhawster a chwalodd. Byddwn yn ceisio adfer eich tabiau a ffenestri pan fydd yn ailgychwyn.\n\nI'n cynorthwyo i ddadansoddi a chywiro'r anhawster, anfonwch adroddiad chwalu atom.
diff --git a/l10n-cy/mail/defines.inc b/l10n-cy/mail/defines.inc
new file mode 100644
index 0000000000..30a2380d7c
--- /dev/null
+++ b/l10n-cy/mail/defines.inc
@@ -0,0 +1,11 @@
+#filter emptyLines
+
+#define MOZ_LANGPACK_CREATOR mozilla.org
+
+# If non-English locales wish to credit multiple contributors, uncomment this
+
+# variable definition and use the format specified.
+
+#define MOZ_LANGPACK_CONTRIBUTORS <em:contributor>Rhoslyn Prys</em:contributor>
+
+#unfilter emptyLines
diff --git a/l10n-cy/mail/installer/custom.properties b/l10n-cy/mail/installer/custom.properties
new file mode 100644
index 0000000000..69e9cf420e
--- /dev/null
+++ b/l10n-cy/mail/installer/custom.properties
@@ -0,0 +1,86 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE:
+
+# This file must be saved as UTF8
+
+# Accesskeys are defined by prefixing the letter that is to be used for the
+# accesskey with an ampersand (e.g. &).
+
+# Do not replace $BrandShortName, $BrandFullName, or $BrandFullNameDA with a
+# custom string and always use the same one as used by the en-US files.
+# $BrandFullNameDA allows the string to contain an ampersand (e.g. DA stands
+# for double ampersand) and prevents the letter following the ampersand from
+# being used as an accesskey.
+
+# You can use \n to create a newline in the string but only when the string
+# from en-US contains a \n.
+
+REG_APP_DESC=Mae $BrandShortName yn rhaglen e-bost cynhwysfawr. Mae $BrandShortName yn cynnal protocolau e-bost IMAP a POP, yn ogystal a gallu fformatio e-bost gydag HTML. O'i fewn mae rheolau sbam, gallu RSS, chwilio cyflym pwerus, gwirio sillafu wrth i chi deipio, blwch derbyn eang, ac mae hidlo negeseuon soffistigedig yn crynhoi set nodweddion cyfoes $BrandShortName.
+CONTEXT_OPTIONS=&Dewisiadau $BrandShortName
+CONTEXT_SAFE_MODE=&Modd Diogel $BrandShortName
+OPTIONS_PAGE_TITLE=Math o Osod
+OPTIONS_PAGE_SUBTITLE=Dewisiadau gosod
+SHORTCUTS_PAGE_TITLE=Llwybrau Byr y Gosod
+SHORTCUTS_PAGE_SUBTITLE=Creu Eiconau'r Rhaglen
+COMPONENTS_PAGE_TITLE=Gosod Cydrannau Ychwanegol
+COMPONENTS_PAGE_SUBTITLE=Cydrannau Dewisol Cymeradwy
+OPTIONAL_COMPONENTS_DESC=Bydd y Gwasanaeth Cynnal yn caniatáu i chi ddiweddaru $BrandShortName yn dawel yn y cefndir.
+MAINTENANCE_SERVICE_CHECKBOX_DESC=&Gosod y Gwasanaeth Cynnal
+SUMMARY_PAGE_TITLE=Crynodeb
+SUMMARY_PAGE_SUBTITLE=Yn barod i osod $BrandShortName
+SUMMARY_INSTALLED_TO=Bydd $BrandShortName yn cael ei osod yn y lleoliad canlynol:
+SUMMARY_REBOOT_REQUIRED_INSTALL=Efallai bydd angen ailgychwyn y cyfrifiadur er mwyn cwblhau'r gosod.
+SUMMARY_REBOOT_REQUIRED_UNINSTALL=Efallai bydd angen ailgychwyn y cyfrifiadur er mwyn cwblhau'r dadosod.
+SUMMARY_TAKE_DEFAULTS=Defnyddio $BrandShortName fel fy rhaglen e-bost rhagosodedig
+SUMMARY_INSTALL_CLICK=Clicio Gosod i barhau.
+SUMMARY_UPGRADE_CLICK=Clicio Diweddaru i barhau.
+SURVEY_TEXT=&Dweud wrthym eich barn am $BrandShortName
+LAUNCH_TEXT=&Cychwyn $BrandFullName nawr
+CREATE_ICONS_DESC=Creu eiconau $BrandShortName:
+ICONS_DESKTOP=&Ar y Bwrdd Gwaith
+ICONS_STARTMENU=&Yn ffolder Rhaglenni Dewislen Cychwyn
+ICONS_QUICKLAUNCH=&Yn y bar Cychwyn Cyflym
+ICONS_TASKBAR=Ar fy &mar tasgau
+WARN_MANUALLY_CLOSE_APP_INSTALL=Rhaid cau $BrandShortName er mwyn parhau gyda'r gosod.\n\nCaewch $BrandShortName er mwyn parhau.
+WARN_MANUALLY_CLOSE_APP_UNINSTALL=Rhaid cau $BrandShortName er mwyn parhau gyda'r dadosod.\n\nCaewch $BrandShortName er mwyn parhau.
+WARN_MANUALLY_CLOSE_APP_LAUNCH=Mae $BrandShortName yn rhedeg yn barod.\n\nCaewch $BrandShortName cyn cychwyn y fersiwn rydych newydd ei osod.
+WARN_WRITE_ACCESS=Nid oes gennych fynediad i ysgrifennu i'r cyfeiriadur gosod.\n\nCliciwch Iawn i ddewis cyfeiriadur gwahanol.
+WARN_DISK_SPACE=Nid oes gennych ddigon o le ar ddisg i osod yn y lleoliad hwn.\n\nCliciwch Iawn i ddewis lleoliad gwahanol.
+WARN_MIN_SUPPORTED_OSVER_MSG=Ymddiheuriadau, nid oes modd gosod $BrandShortName. Mae'r fersiwn hwn o $BrandShortName angen ${MinSupportedVer} neu fwy diweddar. Cliciwch ar y botwm Iawn am wybodaeth bellach.
+WARN_MIN_SUPPORTED_CPU_MSG=Ymddiheuriadau, nid oes modd gosod $BrandShortName. Mae'r fersiwn hwn o $BrandShortName angen prosesydd gyda chefnogaeth ar gyfer ${MinSupportedCPU}. Cliciwch ar y botwm Iawn am wybodaeth bellach.
+WARN_MIN_SUPPORTED_OSVER_CPU_MSG=Ymddiheuriadau, nid oes modd gosod $BrandShortName. Mae'r fersiwn hwn o $BrandShortName angen ${MinSupportedVer} a phrosesydd gyda chefnogaeth ar gyfer ${MinSupportedCPU}. Cliciwch ar y botwm Iawn am wybodaeth bellach.
+WARN_RESTART_REQUIRED_UNINSTALL=Rhaid ailgychwyn y cyfrifiadur er mwyn cwblhau dadosod y fersiwn diwethaf o $BrandShortName. Hoffech chi ailgychwyn nawr?
+WARN_RESTART_REQUIRED_UPGRADE=Rhaid ailgychwyn y cyfrifiadur er mwyn cwblhau'r diweddariad diwethaf o $BrandShortName. Hoffech chi ailgychwyn nawr?
+ERROR_CREATE_DIRECTORY_PREFIX=Gwall wrth greu cyfeiriadur:
+ERROR_CREATE_DIRECTORY_SUFFIX=Cliciwch Diddymu i atal gosod neu\nEto er mwyn ceisio eto.
+
+UN_CONFIRM_PAGE_TITLE=Dad-osod $BrandFullName
+UN_CONFIRM_PAGE_SUBTITLE=Tynnu $BrandFullName oddi ar eich cyfrifiadur.
+UN_CONFIRM_UNINSTALLED_FROM=Bydd $BrandShortName yn cael ei ddadosod o'r lleoliad canlynol:
+UN_CONFIRM_CLICK=Cliciwch Dadosod i barhau.
+
+BANNER_CHECK_EXISTING=Gwirio'r gosodiad presennol…
+
+STATUS_INSTALL_APP=Gosod $BrandShortName…
+STATUS_INSTALL_LANG=Gosod Ffeiliau Iaith (${AB_CD})…
+STATUS_UNINSTALL_MAIN=Dadosod $BrandShortName…
+STATUS_CLEANUP=Glanhau…
+
+# _DESC strings support approximately 65 characters per line.
+# One line
+OPTIONS_SUMMARY=Dewis y math o osod sydd orau gennych, yna clicio Nesaf.
+# One line
+OPTION_STANDARD_DESC=Bydd $BrandShortName yn cael ei osod gyda'r dewisiadau mwyaf cyffredin.
+OPTION_STANDARD_RADIO=&Safonol
+# Two lines
+OPTION_CUSTOM_DESC=Gallwch ddewis dewisiadau unigol i'w gosod. Ar gyfer defnyddwyr uwch.
+OPTION_CUSTOM_RADIO=&Cyfaddasu
+
+# LOCALIZATION NOTE:
+# The following text replaces the Install button text on the summary page.
+# Verify that the access key for InstallBtn (in override.properties) and
+# UPGRADE_BUTTON is not already used by SUMMARY_TAKE_DEFAULTS.
+UPGRADE_BUTTON=&Diweddaru
diff --git a/l10n-cy/mail/installer/mui.properties b/l10n-cy/mail/installer/mui.properties
new file mode 100644
index 0000000000..afb3b13d1c
--- /dev/null
+++ b/l10n-cy/mail/installer/mui.properties
@@ -0,0 +1,60 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# To make the l10n tinderboxen see changes to this file you can change a value
+# name by adding - to the end of the name followed by chars (e.g. Branding-2).
+
+# LOCALIZATION NOTE:
+
+# This file must be saved as UTF8
+
+# Accesskeys are defined by prefixing the letter that is to be used for the
+# accesskey with an ampersand (e.g. &).
+
+# Do not replace $BrandShortName, $BrandFullName, or $BrandFullNameDA with a
+# custom string and always use the same one as used by the en-US files.
+# $BrandFullNameDA allows the string to contain an ampersand (e.g. DA stands
+# for double ampersand) and prevents the letter following the ampersand from
+# being used as an accesskey.
+
+# You can use \n to create a newline in the string but only when the string
+# from en-US contains a \n.
+MUI_TEXT_WELCOME_INFO_TITLE=Croeso i Ddewin Gosod $BrandFullNameDA
+MUI_TEXT_WELCOME_INFO_TEXT=Bydd y dewin yn eich tywys wrth osod $BrandFullNameDA.\n\nArgymhellir eich bod yn cau pob rhaglen arall cyn cychwyn gosod. Bydd hyn yn ei gwneud yn bosibl i ddiweddaru'r ffeiliau system berthnasol heb fod angen ailgychwyn eich cyfrifiadur.\n\n$_CLICK
+MUI_TEXT_COMPONENTS_TITLE=Dewis Cydrannau
+MUI_TEXT_COMPONENTS_SUBTITLE=Dewiswch pa nodweddion $BrandFullNameDA rydych am eu gosod.
+MUI_INNERTEXT_COMPONENTS_DESCRIPTION_TITLE=Disgrifiad
+MUI_INNERTEXT_COMPONENTS_DESCRIPTION_INFO=Rhowch eich llygoden ar draws cydran i weld ei ddisgrifiad.
+MUI_TEXT_DIRECTORY_TITLE=Dewis Lleoliad Gosod
+MUI_TEXT_DIRECTORY_SUBTITLE=Dewiswch y ffolder lle mae gosod $BrandFullNameDA.
+MUI_TEXT_INSTALLING_TITLE=Gosod
+MUI_TEXT_INSTALLING_SUBTITLE=Arhoswch tra bod $BrandFullNameDA yn cael ei osod.
+MUI_TEXT_FINISH_TITLE=Wedi Cwblhau Gosod
+MUI_TEXT_FINISH_SUBTITLE=Gosod wedi'i gwblhau'n llwyddiannus.
+MUI_TEXT_ABORT_TITLE=Atalwyd y Gosod
+MUI_TEXT_ABORT_SUBTITLE=Ni chwblhawyd y gosod yn llwyddiannus.
+MUI_BUTTONTEXT_FINISH=&Gorffen
+MUI_TEXT_FINISH_INFO_TITLE=Cwblhau Dewin Gosod $BrandFullNameDA
+MUI_TEXT_FINISH_INFO_TEXT=Mae $BrandFullNameDA. wedi'i osod ar eich cyfrifiadur.\n\nCliciwch Gorffen i gau'r dewin.
+MUI_TEXT_FINISH_INFO_REBOOT=Rhaid ailgychwyn eich cyfrifiadur er mwyn cwblhau gosod $BrandFullNameDA. Hoffech chi wneud hynny?
+MUI_TEXT_FINISH_REBOOTNOW=Ail gychwyn nawr
+MUI_TEXT_FINISH_REBOOTLATER=Rwyf am ailgychwyn yn hwyrach
+MUI_TEXT_STARTMENU_TITLE=Dewis Ffolder Dewislen Cychwyn
+MUI_TEXT_STARTMENU_SUBTITLE=Dewiswch ffolder Dewislen Cychwyn ar gyfer llwybrau byr $BrandFullNameDA.
+MUI_INNERTEXT_STARTMENU_TOP=Dewiswch ffolder Dewislen Cychwyn lle'r hoffech greu llwybrau byr y rhaglen. Gallwch osod enw i'r ffolder newydd.
+MUI_TEXT_ABORTWARNING=Ydych chi'n siŵr eich bod am adael Gosod $BrandFullName?
+MUI_UNTEXT_WELCOME_INFO_TITLE=Croeso i Ddewin Dadosod $BrandFullNameDA
+MUI_UNTEXT_WELCOME_INFO_TEXT=Bydd y dewin yn eich tywys drwy ddadosod $BrandFullNameDA.\n\nCyn cychwyn dadosod gwnewch yn siwr nad yw $BrandFullNameDA yn rhedeg.\n\n$_CLICK
+MUI_UNTEXT_CONFIRM_TITLE=Dadosod $BrandFullNameDA
+MUI_UNTEXT_CONFIRM_SUBTITLE=Tynnu $BrandFullNameDA oddi ar eich cyfrifiadur.
+MUI_UNTEXT_UNINSTALLING_TITLE=Dadosod
+MUI_UNTEXT_UNINSTALLING_SUBTITLE=Arhoswch tra bo $BrandFullNameDA yn cael ei dadosod.
+MUI_UNTEXT_FINISH_TITLE=Dadosod wedi'i gwblhau
+MUI_UNTEXT_FINISH_SUBTITLE=Dadosod wedi'i gwblhau'n llwyddiannus.
+MUI_UNTEXT_ABORT_TITLE=Atal y Dadosod
+MUI_UNTEXT_ABORT_SUBTITLE=Ni chwyblhawyd y dadosod yn llwyddiannus.
+MUI_UNTEXT_FINISH_INFO_TITLE=Cwblhau Dewin Dadosod $BrandFullNameDA
+MUI_UNTEXT_FINISH_INFO_TEXT=Mae $BrandFullNameDA wedi'i dadosod o'ch cyfrifiadur.\n\nCliciwch Gorffen i gau'r dewin.
+MUI_UNTEXT_FINISH_INFO_REBOOT=Rhaid ailgychwyn eich cyfrifiadur er mwyn cwblhau dadosod $BrandFullNameDA. Hoffech chi ailgychwyn?
+MUI_UNTEXT_ABORTWARNING=Ydych chi'n siwr eich bod am adael dadosod $BrandFullName Uninstall?
diff --git a/l10n-cy/mail/installer/override.properties b/l10n-cy/mail/installer/override.properties
new file mode 100644
index 0000000000..dd70aa14f2
--- /dev/null
+++ b/l10n-cy/mail/installer/override.properties
@@ -0,0 +1,86 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# LOCALIZATION NOTE:
+
+# This file must be saved as UTF8
+
+# Accesskeys are defined by prefixing the letter that is to be used for the
+# accesskey with an ampersand (e.g. &).
+
+# Do not replace $BrandShortName, $BrandFullName, or $BrandFullNameDA with a
+# custom string and always use the same one as used by the en-US files.
+# $BrandFullNameDA allows the string to contain an ampersand (e.g. DA stands
+# for double ampersand) and prevents the letter following the ampersand from
+# being used as an accesskey.
+
+# You can use \n to create a newline in the string but only when the string
+# from en-US contains a \n.
+
+# Strings that require a space at the end should be enclosed with double
+# quotes and the double quotes will be removed. To add quotes to the beginning
+# and end of a string enclose the strin with an additional double quote
+# (e.g. ""This will include quotes"").
+
+SetupCaption=Gosod $BrandFullName
+UninstallCaption=Dadosod $BrandFullName
+BackBtn=< &Nôl
+NextBtn=&Nesaf >
+AcceptBtn=&Rwy'n derbyn amodau'r Cytundeb Trwyddedu
+DontAcceptBtn=&Nid wyf yn derbyn amodau'r Cytundeb Trwyddedu
+InstallBtn=&Gosod
+UninstallBtn=&Dadosod
+CancelBtn=Diddymu
+CloseBtn=&Cau
+BrowseBtn=&Pori…
+ShowDetailsBtn=&Dangos manylion
+ClickNext=Cliciwch Nesaf i barhau.
+ClickInstall=Cliciwch Gosod i gychwyn gosod.
+ClickUninstall=Cliciwch Dadosod i gychwyn dadosod.
+Completed=Cwblhawyd
+LicenseTextRB=Darllenwch y cytundeb trwyddedu cyn gosod $BrandFullNameDA. Os ydych yn derbyn amodau’r cytundeb, dewiswch y dewis cyntaf isod. $_CLICK
+ComponentsText=Ticiwch y cydrannau rydych am eu gosod a dad dicio'r cydrannau nad ydych am eu gosod. $_CLICK
+ComponentsSubText2_NoInstTypes=Dewiswch gydrannau i'w gosod:
+DirText=Bydd y gosod yn gosod $BrandFullNameDA yn y ffolder canlynol. I'w osod mewn ffolder gwahanol, cliciwch Pori a dewis ffolder arall. $_CLICK
+DirSubText=Ffolder Cyrchfan
+DirBrowseText=Dewiswch y ffolder i osod $BrandFullNameDA ynddi:
+SpaceAvailable="Lle ar gael: "
+SpaceRequired="Lle angenrheidiol: "
+UninstallingText=Bydd $BrandFullNameDA yn cael ei ddadosod o'r ffolder canlynol. $_CLICK
+UninstallingSubText=Dadosod o:
+FileError=Gwall wrth agor ffeil i'w ysgrifennu: \r\n\r\n$0\r\n\r\nCiciwch Atal i atal y gosod,\r\nAil-geisio i geisio eto neu\r\nAnwybyddu i hepgor y ffeil.
+FileError_NoIgnore=Gwall wrth agor ffeil i'w ysgrifennu: \r\n\r\n$0\r\n\r\nAil-geisio i geisio eto neu\r\nDiddymu i atal y gosod.
+CantWrite="Methu ysgrifennu: "
+CopyFailed=Methodd copïo
+CopyTo="Copïo i "
+Registering="Cofrestru: "
+Unregistering="Dadgofrestru: "
+SymbolNotFound="Methu canfod symbol: "
+CouldNotLoad="Methu llwytho: "
+CreateFolder="Creu ffolder: "
+CreateShortcut="Creu llwybr byr: "
+CreatedUninstaller="Creu dadosodwr: "
+Delete="Dileu ffeil: "
+DeleteOnReboot="Dileu wrth ailgychwyn: "
+ErrorCreatingShortcut="Gwall wrth greu llwybr byr: "
+ErrorCreating="Creu gwall: "
+ErrorDecompressing=Gwall wrth ddatgywasgu data! Gosodwr llwgr?
+ErrorRegistering=Gwall cofrestru DLL
+ExecShell="ExecShell: "
+Exec="Gweithredu: "
+Extract="Echdynnu: "
+ErrorWriting="Echdynnu: gwall ysgrifennu i ffeil "
+InvalidOpcode=Gosodwr gwallus: opcode annilys
+NoOLE="Dim OLE ar gyfer: "
+OutputFolder="Ffolder allbwn: "
+RemoveFolder="Tynnu Ffolder: "
+RenameOnReboot="Ailenwi wrth ailgychwyn: "
+Rename="Ailenwi: "
+Skipped="Hepgorwyd: "
+CopyDetails=Copïo Manylion i'r Clipfwrdd
+LogInstall=Cofnodi'r broses osod
+Byte=B
+Kilo=K
+Mega=M
+Giga=G
diff --git a/l10n-cy/mail/messenger/aboutAddonsExtra.ftl b/l10n-cy/mail/messenger/aboutAddonsExtra.ftl
new file mode 100644
index 0000000000..9723028e4d
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutAddonsExtra.ftl
@@ -0,0 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+add-on-options-button =
+    .title = Dewisiadau Ychwanegion
+
+add-on-search-alternative-button-label = Canfod ychwanegyn arall
+
+atn-addons-heading-search-input =
+    .placeholder = Chwilio addons.thunderbird.net
+
diff --git a/l10n-cy/mail/messenger/aboutDialog.ftl b/l10n-cy/mail/messenger/aboutDialog.ftl
new file mode 100644
index 0000000000..bb65b1dfec
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutDialog.ftl
@@ -0,0 +1,18 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+about-update-whats-new = Be sy'n Newydd
+aboutDialog-title =
+    .title = Ynghylch { -brand-full-name }
+# Example of resulting string: 66.0.1 (64-bit)
+# Variables:
+#   $version (String): version of Thunderbird, e.g. 66.0.1
+#   $bits (Number): bits of the architecture (32 or 64)
+aboutDialog-version = { $version } ({ $bits }-did)
+# Example of resulting string: 66.0a1 (2019-01-16) (64-bit)
+# Variables:
+#   $version (String): version of Thunderbird for Daily builds, e.g. 66.0a1
+#   $isodate (String): date in ISO format, e.g. 2019-01-16
+#   $bits (Number): bits of the architecture (32 or 64)
+aboutDialog-version-nightly = { $version } ({ $isodate }) ({ $bits }-did)
diff --git a/l10n-cy/mail/messenger/aboutImport.ftl b/l10n-cy/mail/messenger/aboutImport.ftl
new file mode 100644
index 0000000000..7b1526d2a9
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutImport.ftl
@@ -0,0 +1,287 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+import-page-title = Mewnforio
+
+export-page-title = Allforio
+
+## Header
+
+import-start = Teclyn Mewnforio
+
+import-start-title = Mewnforio gosodiadau neu ddata o raglen neu ffeil.
+
+import-start-description = Dewiswch y ffynhonnell rydych chi am fewnforio ohoni. Yn ddiweddarach, byddwn yn gofyn i chi ddewis pa ddata sydd angen ei fewnforio.
+
+import-from-app = Mewnforio o'r Rhaglen
+
+import-file = Mewnforio o ffeil
+
+import-file-title = Dewiswch ffeil i fewnforio ei chynnwys.
+
+import-file-description = Dewiswch fewnforio proffil, llyfrau cyfeiriadau neu galendrau sydd wedi'u cadw wrth gefn yn  flaenorol.
+
+import-address-book-title = Mewnforio ffeil Llyfr Cyfeiriadau
+
+import-calendar-title = Mewnforio ffeil Calendr
+
+export-profile = Allforio
+
+## Buttons
+
+button-back = Nôl
+
+button-continue = Parhau
+
+button-export = Allforio
+
+button-finish = Gorffen
+
+## Import from app steps
+
+app-name-thunderbird = Thunderbird
+
+app-name-seamonkey = SeaMonkey
+
+app-name-outlook = Outlook
+
+app-name-becky = Becky! Internet Mail
+
+app-name-apple-mail = Apple Mail
+
+source-thunderbird = Mewnforio o osodiad { app-name-thunderbird } arall
+
+source-thunderbird-description = Mewnforio gosodiadau, hidlwyr, negeseuon, a data arall o broffil { app-name-thunderbird }.
+
+source-seamonkey = Mewnforio o osodiad { app-name-seamonkey }
+
+source-seamonkey-description = Mewnforio gosodiadau, hidlwyr, negeseuon, a data arall o broffil { app-name-seamonkey }.
+
+source-outlook = Mewnforio o { app-name-outlook }
+
+source-outlook-description = Mewnforio cyfrifon, llyfrau cyfeiriadau, a negeseuon o { app-name-outlook }.
+
+source-becky = Mewnforio o { app-name-becky }
+
+source-becky-description = Mewnforio llyfrau cyfeiriadau a negeseuon o { app-name-becky }.
+
+source-apple-mail = Mewnforio o { app-name-apple-mail }
+
+source-apple-mail-description = Mewnforio negeseuon o { app-name-apple-mail }.
+
+source-file2 = Mewnforio o ffeil
+
+source-file-description = Dewiswch ffeil i fewnforio llyfrau cyfeiriadau, calendrau, neu gopi wrth gefn o broffil (ffeil ZIP).
+
+## Import from file selections
+
+file-profile2 = Mewnforio Proffil Wrth Gefn
+
+file-profile-description = Dewiswch broffil Thunderbird sydd wedi'i gadw wrth gefn yn flaenorol (.zip)
+
+file-calendar = Mewnforio Calendrau
+
+file-calendar-description = Dewiswch ffeil sy'n cynnwys Calendrau neu Ddigwyddiadau wedi'u hallforio (.ics)
+
+file-addressbook = Mewnforio Llyfrau Cyfeiriadau
+
+file-addressbook-description = Dewiswch ffeil sy'n cynnwys Llyfrau Cyfeiriadau a Chysylltiadau wedi'u hallforio
+
+## Import from app profile steps
+
+from-app-thunderbird = Mewnforio o broffil { app-name-thunderbird }
+
+from-app-seamonkey = Mewnforio o broffil { app-name-seamonkey }
+
+from-app-outlook = Mewnforio o { app-name-outlook }
+
+from-app-becky = Mewnforio o { app-name-becky }
+
+from-app-apple-mail = Mewnforio o { app-name-apple-mail }
+
+profiles-pane-title-thunderbird = Mewnforio Gosodiadau a Data o broffil { app-name-thunderbird }.
+
+profiles-pane-title-seamonkey = Mewnforio Gosodiadau a Data o broffil { app-name-seamonkey }.
+
+profiles-pane-title-outlook = Mewnforio Data o { app-name-outlook }.
+
+profiles-pane-title-becky = Mewnforio Data o { app-name-becky }.
+
+profiles-pane-title-apple-mail = Mewnforio Negeseuon o { app-name-apple-mail }.
+
+profile-source = Mewnforio o broffil
+
+# $profileName (string) - name of the profile
+profile-source-named = Mewnforio o'r proffil <strong>"{ $profileName }"</strong>
+
+profile-file-picker-directory = Dewiswch ffolder proffil
+
+profile-file-picker-archive = Dewiswch ffeil <strong>ZIP</strong>
+
+profile-file-picker-archive-description = Rhaid i'r ffeil ZIP fod yn llai na 2GB.
+
+profile-file-picker-archive-title = Dewiswch ffeil ZIP (llai na 2GB)
+
+items-pane-title2 = Dewiswch beth i'w fewnforio:
+
+items-pane-directory = Cyfeiriadur:
+
+items-pane-profile-name = Enw proffil:
+
+items-pane-checkbox-accounts = Cyfrifon a Gosodiadau
+
+items-pane-checkbox-address-books = Llyfrau Cyfeiriadau
+
+items-pane-checkbox-calendars = Calendrau
+
+items-pane-checkbox-mail-messages = Negeseuon E-bost
+
+items-pane-override = Ni fydd unrhyw ddata presennol neu'r un fath yn cael ei drosysgrifo.
+
+## Import from address book file steps
+
+import-from-addr-book-file-description = Dewiswch y fformat ffeil sy'n cynnwys eich data Llyfr Cyfeiriadau.
+
+addr-book-csv-file = Ffeil wedi'i gwahanu gan goma neu dab (.csv, .tsv)
+
+addr-book-ldif-file = Ffeil LDIF (.ldif)
+
+addr-book-vcard-file = Ffeil vCard (.vcf, .vcard)
+
+addr-book-sqlite-file = Ffeil cronfa ddata SQLite (.sqlite)
+
+addr-book-mab-file = Ffeil cronfa ddata Mork (.mab)
+
+addr-book-file-picker = Dewiswch ffeil llyfr cyfeiriadau
+
+addr-book-csv-field-map-title = Cydweddu enwau meysydd
+
+addr-book-csv-field-map-desc = Dewiswch feysydd llyfr cyfeiriadau sy'n cyfateb i'r meysydd ffynhonnell. Dad-diciwch y meysydd nad ydych am eu mewnforio.
+
+addr-book-directories-title = Dewiswch o ble i fewnforio'r data a ddewiswyd
+
+addr-book-directories-pane-source = Ffeil ffynhonnell:
+
+# $addressBookName (string) - name of the new address book that would be created.
+addr-book-import-into-new-directory2 = Crëwch gyfeiriadur newydd o'r enw <strong>"{ $addressBookName }"</strong>
+
+# $addressBookName (string) - name of the address book to import into
+addr-book-summary-title = Mewnforio'r data a ddewiswyd i'r cyfeiriadur " { $addressBookName } "
+
+# $addressBookName (string) - name of the address book that will be created.
+addr-book-summary-description = Bydd llyfr cyfeiriadau newydd o'r enw " { $addressBookName } " yn cael ei greu.
+
+## Import from calendar file steps
+
+import-from-calendar-file-desc = Dewiswch y ffeil iCalendar (.ics) yr hoffech ei mewnforio.
+
+calendar-items-title = Dewiswch pa eitemau i'w mewnforio.
+
+calendar-items-loading = Wrthi'n llwytho eitemau…
+
+calendar-items-filter-input =
+    .placeholder = Hidlo eitemau…
+
+calendar-select-all-items = Dewis y cyfan
+
+calendar-deselect-all-items = Dad-ddewis y cyfan
+
+calendar-target-title = Dewiswch ble i fewnforio'r eitemau a ddewiswyd.
+
+# $targetCalendar (string) - name of the new calendar that would be created
+calendar-import-into-new-calendar2 = Crëwch galendr newydd o'r enw <strong>"{ $targetCalendar }"</strong>
+
+# $itemCount (number) - count of selected items (tasks, events) that will be imported
+# $targetCalendar (string) - name of the calendar the items will be imported into
+calendar-summary-title =
+    { $itemCount ->
+        [zero] Mewnforio { $itemCount } eitem i'r calendr " { $targetCalendar } "
+        [one] Mewnforio un eitem i'r calendr " { $targetCalendar } "
+        [two] Mewnforio { $itemCount } eitem i'r calendr " { $targetCalendar } "
+        [few] Mewnforio { $itemCount } eitem i'r calendr " { $targetCalendar } "
+        [many] Mewnforio { $itemCount } eitem i'r calendr " { $targetCalendar } "
+       *[other] Mewnforio { $itemCount } eitem i'r calendr " { $targetCalendar } "
+    }
+
+# $targetCalendar (string) - name of the calendar that will be created
+calendar-summary-description = Bydd calendr newydd o'r enw " { $targetCalendar } " yn cael ei greu.
+
+## Import dialog
+
+# $progressPercent (string) - percent formatted progress (for example "10%")
+progress-pane-importing2 = Wrthi'n mewnforio… { $progressPercent }
+
+# $progressPercent (string) - percent formatted progress (for example "10%")
+progress-pane-exporting2 = Wrthi'n allforio… { $progressPercent }
+
+progress-pane-finished-desc2 = Gorffen.
+
+error-pane-title = Gwall
+
+error-message-zip-file-too-big2 = Mae'r ffeil zip a ddewiswyd yn fwy na 2GB. Echdynnwch hi'n gyntaf, yna ei mewnforio o'r ffolder cafodd ei hechdynnu.
+
+error-message-extract-zip-file-failed2 = Wedi methu echdynnu'r ffeil zip. Echdynwch hi â llaw, yna ei mewnforio o'r ffolder wedi'i hechdynnu yn lle hynny.
+
+error-message-failed = Methodd y mewnforio yn annisgwyl, efallai y bydd mwy o wybodaeth ar gael yn y Consol Gwallau.
+
+error-failed-to-parse-ics-file = Heb ganfod unrhyw eitemau i'w mewnforio yn y ffeil.
+
+error-export-failed = Methodd y mewnforio yn annisgwyl, efallai y bydd rhagor o wybodaeth ar gael yn y Consol Gwallau.
+
+error-message-no-profile = Heb ganfod proffil.
+
+## <csv-field-map> element
+
+csv-first-row-contains-headers = Mae'r rhes gyntaf yn cynnwys enwau meysydd
+
+csv-source-field = Maes ffynhonnell
+
+csv-source-first-record = Cofnod cyntaf
+
+csv-source-second-record = Ail gofnod
+
+csv-target-field = Maes llyfr cyfeiriadau
+
+## Export tab
+
+export-profile-title = Allforiwch gyfrifon, negeseuon, llyfrau cyfeiriadau, a gosodiadau i ffeil ZIP.
+
+export-profile-description = Os yw eich proffil presennol yn fwy na 2GB, rydym yn awgrymu eich bod yn gwneud copi wrth gefn ohono ar eich cyfer chi eich hun.
+
+export-open-profile-folder = Agor ffolder proffil
+
+export-file-picker2 = Allforio i ffeil ZIP
+
+export-brand-name = { -brand-product-name }
+
+## Summary pane
+
+summary-pane-title = Data i'w fewnforio
+
+summary-pane-start = Cychwyn Mewnforio
+
+summary-pane-warning = Bydd angen ailgychwyn { -brand-product-name } pan fydd y mewnforio wedi'i gwblhau.
+
+summary-pane-start-over = Ailgychwyn y Teclyn Mewnforio
+
+## Footer area
+
+footer-help = Angen cymorth?
+
+footer-import-documentation = Dogfennaeth gosod
+
+footer-export-documentation = Dogfennaeth allforio
+
+footer-support-forum = Fforwm cefnogi
+
+## Step navigation on top of the wizard pages
+
+step-list =
+    .aria-label = Camau mewnforio
+
+step-confirm = Cadarnhau
+
+# Variables:
+# $number (number) - step number
+step-count = { $number }
diff --git a/l10n-cy/mail/messenger/aboutProfilesExtra.ftl b/l10n-cy/mail/messenger/aboutProfilesExtra.ftl
new file mode 100644
index 0000000000..365a877011
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutProfilesExtra.ftl
@@ -0,0 +1,5 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+profiles-launch-profile-plain = Agor proffil
diff --git a/l10n-cy/mail/messenger/aboutRights.ftl b/l10n-cy/mail/messenger/aboutRights.ftl
new file mode 100644
index 0000000000..0d99e1fdcd
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutRights.ftl
@@ -0,0 +1,30 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+rights-title = Ynghylch eich hawliau
+rights-intro = Mae { -brand-full-name } yn feddalwedd cod agored rhydd a rhad, wedi ei adeiladu gan gymuned o filoedd o bobl ar draws y byd i gyd. Mae yna rhai pethau i chi gael gwybod:
+rights-intro-point-1 = Mae { -brand-short-name } ar gael i chi o dan amodau'r <a data-l10n-name="mozilla-public-license-link">Trwydded Gyhoeddus Mozilla</a>. Mae hyn yn golygu y cewch ddefnyddio, gopïo a dosbarthu { -brand-short-name } i eraill.  Mae croeso i chi newid cod ffynhonnell { -brand-short-name } yn ôl eich angen. Mae Trwydded Gyhoeddus Mozilla yn rhoi'r hawl i chi ddosbarthu'r fersiwn rydych wedi ei newid.
+rights-intro-point-2 = Nid ydych yn derbyn unrhyw hawliau nod masnachu na thrwyddedau i nod masnach y Mozilla Foundation neu unrhyw barti, gan gynnwys heb gyfyngiadau i enw na logo Thunderbird . Mae gwybodaeth bellach am nodau masnach i’w cael <a data-l10n-name="mozilla-trademarks-link">yma</a>.
+rights-intro-point-3 = Mae rhai nodweddion yn { -brand-short-name }, megis yr Adroddwr Chwalu, yn rhoi'r dewis i chi gyfrannu adborth i { -vendor-short-name }. Drwy ddewis cyflwyno adborth rydych yn rhoi i { -vendor-short-name } ganiatâd i ddefnyddio'r adborth i wella ei gynnyrch, i gyhoeddi'r adborth ar ei wefannau, ac i ddosbarthu'r adborth.
+rights-intro-point-4 = Mae sut rydym yn defnyddio y data personol ac adborth rydych wedi ei gyflwyno i { -vendor-short-name } drwy { -brand-short-name } yn cael ei ddisgrifio yn <a data-l10n-name="mozilla-privacy-policy-link">Polisi Preifatrwydd { -brand-short-name }</a>.
+rights-intro-point-4-unbranded = Rhaid rhestri unrhyw bolisïau preifatrwydd perthnasol yma.
+rights-intro-point-5 = Mae rhai nodweddion { -brand-short-name } yn gwneud defnydd p wasanaethau gwybodaeth gwe, er hynny nid ydym yn gallu gwarantu eu bod yn 100% yn gywir nac yn rhydd o wallau. Mae rhagor o fanylion, gan gynnwys gwybodaeth ar sut i'w hanalluogi i'w cael yn yr <a data-l10n-name="mozilla-service-terms-link">amodau gwasanaeth</a>.
+rights-intro-point-5-unbranded = Os yw'r cynnyrch yn cynnwys gwasanaethau gwe, rhaid cysylltu unrhyw amodau gwasanaeth perthnasol ar gyfer y gwasanaeth(au) i'r adran <a data-l10n-name="mozilla-website-services-link">Gwasanaethau Gwefan</a> Gwe.
+rights-intro-point-6 = Er mwyn chwarae rhai mathau o gynnwys fideo, mae { -brand-short-name } yn llwytho i lawr rhywfaint o gynnwys modiwlau dadgryptio gan drydydd partïon.
+rights-webservices-header = Gwasanaethau Gwybodaeth Gwe { -brand-full-name }
+rights-webservices2 = Mae { -brand-full-name } yn defnyddio gwasanaethau gwybodaeth gwe ("Gwasanaethau") i ddarparu rhai o'r nodweddion sy'n cael eu darparu ar eich cyfer yn y fersiwn yma o { -brand-short-name } o fewn yr amodau disgrifir isod. Os nad ydych am ddefnyddio un neu fwy o'r Gwasanaethau neu mae'r amodau yn annerbyniol, mae modd i chi analluogi'r nodwedd neu'r Gwasanaeth(au). Mae gwybodaeth ar sut i analluogi nodwedd neu Wasanaeth penodol i'w cael <a data-l10n-name="mozilla-disable-service-link">yma</a>. Mae modd analluogi nodweddion a Gwasanaethau eraill yn newisiadau'r rhaglen.
+rights-locationawarebrowsing = <strong>Pori Ymwybodol o Leoliad: </strong>yn ddewis i chi bob tro.  Ni fydd gwybodaeth yn cael ei anfon heb eich caniatâd.  Os hoffech chi analluogi'r nodwedd yn llwyr, dilynwch y camau hyn:
+rights-locationawarebrowsing-term-1 = Yn y bar URL, teipiwch <code>about:config</code>
+rights-locationawarebrowsing-term-2 = Teipio geo.enabled
+rights-locationawarebrowsing-term-3 = Clic dwbl i'r dewis geo.enabled
+rights-locationawarebrowsing-term-4 = Mae Pori Ymwybodol o Leoliad wedi ei analluogi
+rights-webservices-unbranded = Rhaid cynnwys yn fan hyn, drosolwg o'r gwasanaeth gwefan gwe mae'r cynnyrch yn ei gynnwys, ynghyd â chyfarwyddiadau ar sut i'w hatal os yn berthnasol.
+rights-webservices-term-unbranded = Rhaid rhestru amodau gwasanaethau gwe yma.
+rights-webservices-term-1 = Mae { -vendor-short-name } a'i gyfranwyr, trwyddedwyr, a phartneriaid yn gweithio i ddarparu'r Gwasanaethau mwyaf cywir a chyfredol.  Er hynny, nid oes modd i ni warantu fod y wybodaeth yn gynhwysfawr a diwall.  Er enghraifft, efallai na fydd y Gwasanaeth Pori Diogel yn adnabod rhai gwefannau anniogel ac efallai adnabod rhai gwefannau diogel ar gam. Mae pob lleoliad sy'n cael ei ddychwelyd gan ein darparwyr gwasanaeth ar gyfer y Gwasanaeth Ymwybodol o Leoliad yn amcanion yn unig. Nid ydym ni na'r darparwyr gwasanaeth yn gallu gwarantu cywirdeb y lleoliadau hyn.
+rights-webservices-term-2 = Gall { -vendor-short-name } atal neu newid y Gwasanaethau yn ôl eu mympwy.
+rights-webservices-term-3 = Mae croeso i chi ddefnyddio'r Gwasanaethau hyn gyda'r fersiwn yma o { -brand-short-name }, ac mae { -vendor-short-name } rhoi ei hawl i chi wneud hynny.  Mae { -vendor-short-name } a'i drwyddedwyr yn diogelu pob hawl arall yn y Gwasanaethau.  Nid yw'r amodau wedi eu hanelu at gyfyngu unrhyw hawliau o dan drwyddedau cod agored sy'n perthyn i { -brand-short-name } ac i'r fersiynau perthnasol o ffynonellau cod { -brand-short-name }.
+rights-webservices-term-4 = <strong>Mae'r gwasanaeth yn cael ei ddarparu "fel ag y mae".  Mae { -vendor-short-name }, ei gyfranwyr, trwyddedwyr, a dosbarthwyr, yn gwadu unrhyw warant, p'un ai yn cael ei fynegi neu ei awgrymu, gan gynnwys heb gyfyngiad, gwarant fod y Gwasanaethau yn farchnadadwy nac yn addas i'ch pwrpas penodol.  Rydych yn derbyn yr holl risg o ddewis y Gwasanaethau ar gyfer eich pwrpas ac i natur ansawdd a pherfformiad y Gwasanaeth. Nid yw rhai awdurdodau'n caniatáu eithrio neu gyfyngu gwarant sy'n cael ei awgrymu felly efallai nad yw'r gwadiad hwn yn berthnasol i chi.</strong>
+rights-webservices-term-5 = <strong>Yn wahanol i'r hyn sy'n angenrheidiol yn ôl y gyfraith, ni fydd { -vendor-short-name }, ei gyfranwyr, trwyddedwyr a dosbarthwyr yn agored i unrhyw iawndal anuniongyrchol, arbenigol, achlysurol, neu enghreifftiol yn codi o neu mewn unrhyw ffordd yn berthnasol i'r defnydd o { -brand-short-name } a'r Gwasanaethau.   Ni fydd yr atebolrwydd cyfunol o dan yr amodau hyn yn fwy na $500 (pum can dollar). Nid yw rhai awdurdodau yn caniatáu cyfyngu ar rhai materion difrod, felly efallai na fydd hyn yn berthnasol i chi.</strong>
+rights-webservices-term-6 = Gall { -vendor-short-name } ddiweddaru'r amodau yn ôl y galw o bryd i'w gilydd. Nid oes modd newid na dileu'r amodau heb ganiatâd ysgrifenedig { -vendor-short-name }.
+rights-webservices-term-7 = Mae'r amodau yn cael eu rheoli gan gyfreithiau talaith California, UDA, gan hepgor ei ddarpariaethau gwrthdaro cyfreithiol. Os yw unrhyw ran o'r amodau i'w cael heb rym cyfreithiol byd y gweddill yn sefyll mewn grym llawn ac effaith. Os digwydd gwrthdaro rhwng fersiwn sydd wedi ei gyfieithu a'r amodau hyn a'r fersiwn Saesneg, y fersiwn Saesneg fydd yn rheoli.
diff --git a/l10n-cy/mail/messenger/aboutSupportCalendar.ftl b/l10n-cy/mail/messenger/aboutSupportCalendar.ftl
new file mode 100644
index 0000000000..7045b579d4
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutSupportCalendar.ftl
@@ -0,0 +1,33 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+calendars-title = Gosodiadau Calendr
+calendars-table-heading-property = Enw
+calendars-table-heading-value = Gwerth
+calendars-table-name = Enw
+calendars-table-type = Math
+calendars-table-disabled = Analluogwyd
+calendars-table-username = Enw Defnyddiwr
+calendars-table-uri = URI
+calendars-table-refreshinterval = Adnewyddu Cyfnod
+calendars-table-readonly = Darllen-yn-unig
+calendars-table-suppressalarms = Atal Larymau
+calendars-table-cache-enabled = Cache Wedi'i Alluogi
+calendars-table-imip-identity = Hunaniaeth iMIP
+calendars-table-imip-identity-disabled = iMIP Wedi'i Analluogi
+calendars-table-imip-identity-account = Cyfrif iMIP
+calendars-table-organizerid = Enw'r Trefnydd
+calendars-table-forceemailscheduling = Gorfodi Amserlennu E-bost
+calendars-table-capabilities-alarms-popup-supported = Larymau Llamu sy'n cael eu Cefnogi
+calendars-table-capabilities-alarms-oninviations-supported = Larymau Gwahoddiad sy'n cael eu Cefnogi
+calendars-table-capabilities-alarms-maxcount = Uchafswm y Larymau Fesul Digwyddiad
+calendars-table-capabilities-attachments-supported = Atodiadau sy'n cael eu Cefnogi
+calendars-table-capabilities-categories-maxcount = Uchafswm y Categorïau
+calendars-table-capabilities-privacy-supported = Cyflyrau Preifatrwydd sy'n cael eu Cefnogi
+calendars-table-capabilities-priority-supported = Blaenoriaethau sy'n cael eu Cefnogi
+calendars-table-capabilities-events-supported = Digwyddiadau sy'n cael eu Cefnogi
+calendars-table-capabilities-tasks-supported = Tasgau sy'n cael eu Cefnogi
+calendars-table-capabilities-timezones-floating-supported = Amserau Lleol sy'n cael eu Cefnogi
+calendars-table-capabilities-timezones-utc-supported = UTC/GMT yn cael eu Cefnogi
+calendars-table-capabilities-autoschedule-supported = Auto-Amserlennu yn cael ei Gefnogi
diff --git a/l10n-cy/mail/messenger/aboutSupportChat.ftl b/l10n-cy/mail/messenger/aboutSupportChat.ftl
new file mode 100644
index 0000000000..df11065de7
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutSupportChat.ftl
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+chat-title = Cyfrifon Sgwrsio
+chat-table-heading-account = ID
+chat-table-heading-protocol = Protocol
+chat-table-heading-name = Enw
+chat-table-heading-actions = Gweithredoedd
+chat-table-copy-debug-log = Copïo'r Cofnod Dadfygio
+    .title = Copïo gwallau a chofnodio eraill o'r cyfrif sgwrsio hwn i'r clipfwrdd. Gall gynnwys manylion personol fel negeseuon sgwrsio.
diff --git a/l10n-cy/mail/messenger/aboutSupportMail.ftl b/l10n-cy/mail/messenger/aboutSupportMail.ftl
new file mode 100644
index 0000000000..48d2f089be
--- /dev/null
+++ b/l10n-cy/mail/messenger/aboutSupportMail.ftl
@@ -0,0 +1,20 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+accounts-title = Cyfrifon E-bost a Newyddion
+show-private-data-main-text = Cynnwys enwau cyfrifon
+show-private-data-explanation-text = (manylion adnabod personol posib)
+accounts-ID = ID
+accounts-name = Enw
+accounts-incoming-server = Gweinydd Derbyn
+accounts-outgoing-servers = Gweinydd Allan
+accounts-server-name = Enw
+accounts-conn-security = Diogelwch cysylltiad
+accounts-auth-method = Dull dilysu
+accounts-default = Rhagosodiad?
+identity-name = hunaniaeth
+
+send-via-email = Anfon drwy e-bost
+
+app-basics-telemetry = Data Telemetreg
diff --git a/l10n-cy/mail/messenger/accountCentral.ftl b/l10n-cy/mail/messenger/accountCentral.ftl
new file mode 100644
index 0000000000..a24d32a11b
--- /dev/null
+++ b/l10n-cy/mail/messenger/accountCentral.ftl
@@ -0,0 +1,65 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+account-central-title = Croeso i { -brand-full-name }
+account-settings = Gosodiadau Cyfrif
+
+#   $accounts (Number) - the number of configured accounts
+setup-title = Dewis Beth i'w Osod
+about-title = Ynghylch { -brand-full-name }
+resources-title = Adnoddau
+
+release-notes =
+    .title = Ynghylch { -brand-full-name }
+
+email-label = E-bost
+    .aria-label = Cysylltu i'ch cyfeiriad e-bost cyfredol
+email-description = Mae { -brand-short-name } yn galluogi chi gysylltu â'ch cyfrif e-bost presennol, i ddarllen eich e-byst yn gyfleus ac yn effeithlon o fewn y rhaglen.
+
+calendar-label = Calendr
+    .aria-label = Creu calendr newydd
+calendar-description = Mae { -brand-short-name } yn galluogi i chi drin digwyddiadau a chadw trefn. Bydd cysylltu â chalendr pell yn cydweddu'ch holl ddigwyddiadau ar draws eich holl ddyfeisiau.
+
+chat-label = Sgwrs
+    .aria-label = Cysylltu â'ch cyfrif sgwrsio
+chat-description = Mae { -brand-short-name } yn galluogi i chi gysylltu â sawl cyfrif negeseua chwim, gan gynnig cefnogaeth i nifer o lwyfannau amrywiol.
+
+filelink-label = Filelink
+    .aria-label = Gosod Filelink
+filelink-description = Mae { -brand-short-name } yn galluogi i chi greu cyfrif Filelink cwmwl cyfleus i anfon atodiadau mawr yn hawdd.
+
+addressbook-label = Llyfr Cyfeiriadau
+    .aria-label = Creu llyfr cyfeiriadau newydd
+addressbook-description = Mae { -brand-short-name } yn galluogi i chi drefnu'ch holl gysylltiadau mewn llyfr cyfeiriadau. Gallwch hefyd gysylltu â llyfr cyfeiriadau o bell i gydweddu'ch holl gysylltiadau.
+
+feeds-label = Llif
+    .aria-label = Cysylltu â llifau
+feeds-description = Mae { -brand-short-name } yn galluogi i chi gysylltu â phorthwyr RSS / Atom i gael newyddion a diweddariadau o bob man.
+
+newsgroups-label = Grwpiau Newyddion
+    .aria-label = Cysylltu â grŵp newyddion
+newsgroups-description = Mae { -brand-short-name } yn galluogi i chi gysylltu â'r holl grwpiau newyddion yr hoffech chi
+
+import-title = Mewnforio o Raglen Arall
+import-paragraph2 = Mae { -brand-short-name } yn galluogi i chi fewnforio negeseuon e-bost, cofnodion llyfr cyfeiriadau, tanysgrifiadau llif, dewisiadau, a/neu hidlwyr o raglenni e-bost eraill a fformatau llyfrau cyfeiriadau cyffredin.
+
+import-label = Mewnforio
+    .aria-label = Mewnforio data o raglenni eraill
+
+about-paragraph = Thunderbird yw'r brif raglen e-bost a chalendr, croes blatfform, cod agored, sydd ar gael am ddim ar gyfer defnydd busnes neu bersonol. Rydym am barhau i'w gadw'n ddiogel ac i'w wella i'r dyfodol. Bydd rhoddion yn caniatáu i ni gyflogi datblygwyr, talu am isadeiledd a pharhau i'w wella.
+
+about-paragraph-consider-donation = <b>Mae Thunderbird yn cael ei ariannu gan ddefnyddwyr fel chi! Os ydych chi'n hoffi Thunderbird, ystyriwch wneud rhodd.</b> Y ffordd orau i wneud yn siŵr fod Thunderbird yn parhau i fod ar gael yw <a data-l10n-name="donation-link"> i wneud cyfraniad.</a>
+
+explore-link = Edrych ar y Nodweddion
+support-link = Cefnogaeth
+involved-link = Ymunwch â ni!
+developer-link = Dogfennaeth Datblygwr
+
+read = Darllen negeseuon
+compose = Ysgrifennu neges newydd
+search = Chwilio drwy'r Negeseuon
+filter = Rheoli hidlau negeseuon
+nntp-subscription = Rheoli tanysgrifiadau grwpiau newyddion
+rss-subscription = Rheoli tanysgrifiadau llif
+e2e = Amgryptio Pen-i-Ben
diff --git a/l10n-cy/mail/messenger/accountManager.ftl b/l10n-cy/mail/messenger/accountManager.ftl
new file mode 100644
index 0000000000..1a489603ed
--- /dev/null
+++ b/l10n-cy/mail/messenger/accountManager.ftl
@@ -0,0 +1,18 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+open-preferences-sidebar-button2 = Gosodiadau { -brand-short-name }
+
+open-addons-sidebar-button = Ychwanegion a Themâu
+
+account-action-add-newsgroup-account =
+    .label = Ychwanegu Cyfrif Grŵp Newyddion…
+    .accesskey = G
+
+server-change-restart-required = Mae angen ailgychwyn i osod enw'r gweinydd neu'r newid enw defnyddiwr.
+
+edit-vcard-dialog-accept-button = Cadw
+    .accesskey = C
+edit-vcard-dialog-cancel-button = Diddymu
+    .accesskey = D
diff --git a/l10n-cy/mail/messenger/accountProvisioner.ftl b/l10n-cy/mail/messenger/accountProvisioner.ftl
new file mode 100644
index 0000000000..962af9f3c0
--- /dev/null
+++ b/l10n-cy/mail/messenger/accountProvisioner.ftl
@@ -0,0 +1,82 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+account-provisioner-tab-title = Cael cyfeiriad e-bost newydd gan ddarparwr gwasanaeth
+
+provisioner-searching-icon =
+    .alt = Yn chwilio…
+
+account-provisioner-title = Creu cyfeiriad e-bost newydd
+
+account-provisioner-description = Defnyddiwch ein partneriaid dibynadwy i gael cyfeiriad e-bost preifat a diogel newydd.
+
+account-provisioner-start-help = Mae'r termau chwilio sydd wedi'u defnyddio'n cael eu anfon at { -vendor-short-name } (<a data-l10n-name="mozilla-privacy-link">Polisi Preifatrwydd</a>) a darparwyr e-bost 3ydd parti <strong>mailfence.com</strong> (<a data-l10n-name="mailfence-privacy-link">Polisi Preifatrwydd</a>, <a data-l10n-name="mailfence-tou-link">Telerau Defnyddio</ a >) a <strong>gandi.net</strong> (<a data-l10n-name="gandi-privacy-link">Polisi Preifatrwydd</a>, <a data-l10n-name="gandi-tou-link">Amodau Defnydd</a>) i ganfod cyfeiriadau e-bost sydd ar gael.
+
+account-provisioner-mail-account-title = Prynu cyfeiriad e-bost newydd
+
+account-provisioner-mail-account-description = Mae Thunderbird wedi partneru â <a data-l10n-name="mailfence-home-link">Mailfence</a> i gynnig e-bost preifat a diogel newydd i chi. Credwn y dylai pawb gael e-bost diogel.
+
+account-provisioner-domain-title = Prynwch e-bost a pharth i chi eich hun
+
+account-provisioner-domain-description = Mae Thunderbird wedi partneru â <a data-l10n-name="gandi-home-link">Gandi</a> i gynnig parth cyfaddas i chi. Mae hyn yn caniatáu i chi ddefnyddio unrhyw gyfeiriad ar y parth hwnnw.
+
+## Forms
+
+account-provisioner-mail-input =
+    .placeholder = Eich enw, llysenw neu derm chwilio arall
+
+account-provisioner-domain-input =
+    .placeholder = Eich enw, llysenw neu derm chwilio arall
+
+account-provisioner-search-button = Chwilio
+
+account-provisioner-button-cancel = Diddymu
+
+account-provisioner-button-existing = Defnyddiwch gyfrif e-bost sy'n bodoli eisoes
+
+account-provisioner-button-back = Mynd nôl
+
+## Notifications
+
+account-provisioner-fetching-provisioners = Yn estyn darprwyr…
+
+account-provisioner-connection-issues = Nid ydym yn gallu cyfathrebu gyda'n gweinydd cofrestru. Gwiriwch eich cysylltiad.
+
+account-provisioner-searching-email = Yn chwilio am gyfrifon e-bost sydd ar gael...
+
+account-provisioner-searching-domain = Yn chwilio am y parthau sydd ar gael...
+
+account-provisioner-searching-error = Methu dod o hyd i unrhyw gyfeiriadau i'w cynnig. Ceisiwch newid y termau chwilio.
+
+## Illustrations
+
+account-provisioner-step1-image =
+    .title = Dewiswch pa gyfrif i'w greu
+
+## Search results
+
+# Variables:
+# $count (Number) - The number of domains found during search.
+account-provisioner-results-title =
+    { $count ->
+        [zero] Dim cyfeiriadau ar gael ar gyfer:
+        [one] Un cyfeiriad ar gael ar gyfer:
+        [two] { $count } gyfeiriad ar gael ar gyfer:
+        [few] { $count } cyfeiriad ar gael ar gyfer:
+        [many] { $count } chyfeiriad ar gael ar gyfer:
+       *[other] { $count } cyfeiriad ar gael ar gyfer:
+    }
+
+account-provisioner-mail-results-caption = Gallwch hefyd chwilio am lysenwau neu dermau eraill i ganfod ragor o e-byst eraill.
+
+account-provisioner-domain-results-caption = Gallwch hefyd chwilio am lysenwau neu dermau eraill i ganfod ragor o barthau  eraill.
+
+account-provisioner-free-account = Am Ddim
+
+account-provision-price-per-year = { $price } y flwyddyn
+
+account-provisioner-all-results-button = Dangos yr holl ganlyniadau
+
+account-provisioner-open-in-tab-img =
+    .title = Yn agor mewn Tab newydd
diff --git a/l10n-cy/mail/messenger/accountcreation/accountHub.ftl b/l10n-cy/mail/messenger/accountcreation/accountHub.ftl
new file mode 100644
index 0000000000..79fd08e86c
--- /dev/null
+++ b/l10n-cy/mail/messenger/accountcreation/accountHub.ftl
@@ -0,0 +1,16 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Header
+
+account-hub-brand = { -brand-full-name }
+account-hub-welcome-line = Croeso i <span data-l10n-name="brand-name">{ -brand-full-name }</span>
+account-hub-title = Canolfan Cyfrifon
+
+## Footer
+
+account-hub-release-notes = Nodiadau rhyddhau
+account-hub-support = Cefnogaeth
+account-hub-donate = Cyfrannu
diff --git a/l10n-cy/mail/messenger/accountcreation/accountSetup.ftl b/l10n-cy/mail/messenger/accountcreation/accountSetup.ftl
new file mode 100644
index 0000000000..a8ebc4c8b0
--- /dev/null
+++ b/l10n-cy/mail/messenger/accountcreation/accountSetup.ftl
@@ -0,0 +1,444 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+account-setup-tab-title = Gosod Cyfrif
+
+## Header
+
+account-setup-title = Gosod eich Cyfrif E-bost Cyfredol
+
+account-setup-description =
+    I ddefnyddio'ch cyfeiriad e-bost cyfredol, llenwch eich manylion. <br/>
+    Bydd { -brand-product-name } yn chwilio'n awtomatig am ffurfweddid gweinydd sy'n gweithio ac sy'n cael ei argymell.
+
+account-setup-secondary-description = Bydd { -brand-product-name } yn chwilio'n awtomatig am ffurfweddiad gweinydd sy'n gweithio ac sy'n cael ei argymell.
+
+account-setup-success-title = Cyfrif wedi'i greu'n llwyddiannus
+
+account-setup-success-description = Nawr gallwch chi ddefnyddio'r cyfrif hwn gyda { -brand-short-name }.
+
+account-setup-success-secondary-description = Gallwch wella'r profiad trwy gysylltu gwasanaethau cysylltiedig a ffurfweddu gosodiadau cyfrifon uwch.
+
+## Form fields
+
+account-setup-name-label = Eich enw llawn
+    .accesskey = e
+
+# Note: "John Doe" is a multiple-use name that is used when the true name of a person is unknown. We use this fake name as an input placeholder. Translators should update this to reflect the placeholder name of their language/country.
+account-setup-name-input =
+    .placeholder = John Jones
+
+account-setup-name-info-icon =
+    .title = Eich enw, fel mae'n cael ei ddangos i eraill
+
+
+account-setup-name-warning-icon =
+    .title = { account-setup-name-warning }
+
+account-setup-email-label = Cyfeiriad e-bost
+    .accesskey = C
+
+account-setup-email-input =
+    .placeholder = john.jones@example.com
+
+account-setup-email-info-icon =
+    .title = Eich cyfeiriad e-bost cyfredol
+
+account-setup-email-warning-icon =
+    .title = { account-setup-email-warning }
+
+account-setup-password-label = Cyfrinair
+    .accesskey = C
+    .title = Yn ddewisol, dim ond i'w ddefnyddio i ddilysu'r enw defnyddiwr
+
+account-provisioner-button = Cael cyfeiriad e-bost newydd
+    .accesskey = n
+
+account-setup-password-toggle-show =
+    .title = Dangos cyfrinair mewn testun clir
+
+account-setup-password-toggle-hide =
+    .title = Cuddio cyfrinair
+
+account-setup-remember-password = Cofio'r cyfrinair
+    .accesskey = o
+
+account-setup-exchange-label = Eich mewngofnod
+    .accesskey = m
+
+#   YOURDOMAIN refers to the Windows domain in ActiveDirectory. yourusername refers to the user's account name in Windows.
+account-setup-exchange-input =
+    .placeholder = YOURDOMAIN\yourusername
+
+#   Domain refers to the Windows domain in ActiveDirectory. We mean the user's login in Windows at the local corporate network.
+account-setup-exchange-info-icon =
+    .title = Mewngofnod parth
+
+## Action buttons
+
+account-setup-button-cancel = Diddymu
+    .accesskey = D
+
+account-setup-button-manual-config = Ffurfweddu â llaw
+    .accesskey = F
+
+account-setup-button-stop = Atal
+    .accesskey = A
+
+account-setup-button-retest = Ailbrofi
+    .accesskey = A
+
+account-setup-button-continue = Parhau
+    .accesskey = P
+
+account-setup-button-done = Wedi gorffen
+    .accesskey = W
+
+## Notifications
+
+account-setup-looking-up-settings = Chwilio am y ffurfweddiad…
+
+account-setup-looking-up-settings-guess = Yn chwilio drwy'r ffurfweddiad: Yn rhoi cynnig ar enwau gweinydd cyffredin ...
+
+account-setup-looking-up-settings-half-manual = Yn chwilio drwy'r ffurfweddiad: Yn holi'r gweinydd...
+
+account-setup-looking-up-disk = Yn chwilio drwy'r ffurfweddiad: yn gosod { -brand-short-name }…
+
+account-setup-looking-up-isp = Yn chwilio drwy'r ffurfweddiad: Darparwyr e-bost…
+
+# Note: Do not translate or replace Mozilla. It stands for the public project mozilla.org, not Mozilla Corporation. The database is a generic, public domain facility usable by any client.
+account-setup-looking-up-db = Yn chwilio drwy'r ffurfweddiad: cronfa ddata ISP Mozilla...
+
+account-setup-looking-up-mx = Yn chwilio drwy'r ffurfweddiad: Parthau derbyn e-bost...
+
+account-setup-looking-up-exchange = Yn chwilio drwy'r ffurfweddiad: Gweinydd Exchange...
+
+account-setup-checking-password = Yn gwirio'r cyfrinair...
+
+account-setup-installing-addon = Yn llwytho i lawr a gosod ychwanegyn…
+
+account-setup-success-half-manual = Canfuwyd y gosodiadau canlynol trwy archwilio'r gweinydd hwn:
+
+account-setup-success-guess = Canfuwyd y ffurfweddiad drwy roi cynnig ar enwau gweinydd cyffredin.
+
+account-setup-success-guess-offline = Rydych all-lein. Rydym wedi dyfalu rhai gosodiadau ond bydd angen i chi osod y gosodiadau cywir.
+
+account-setup-success-password = Cyfrinair yn iawn
+
+account-setup-success-addon = Wedi gosod yr ychwanegyn yn llwyddiannus
+
+# Note: Do not translate or replace Mozilla. It stands for the public project mozilla.org, not Mozilla Corporation. The database is a generic, public domain facility usable by any client.
+account-setup-success-settings-db = Ffurfweddiad wedi'i ganfod yng nghronfa ddata ISP Mozilla.
+
+account-setup-success-settings-disk = Ffurfweddiad wedi'i ganfod ar osodiad { -brand-short-name }.
+
+account-setup-success-settings-isp = Ffurfweddiad wedi'i ganfod yn y darparwr e-bost.
+
+# Note: Microsoft Exchange is a product name.
+account-setup-success-settings-exchange = Ffurfweddiad wedi'i ganfod ar gyfer gweinydd Microsoft Exchange.
+
+## Illustrations
+
+account-setup-step1-image =
+    .title = Gosodiad cychwynnol
+
+account-setup-step2-image =
+    .title = Yn llwytho…
+
+account-setup-step3-image =
+    .title = Wedi canfod ffurfweddiad
+
+account-setup-step4-image =
+    .title = Gwall cysylltiad
+
+account-setup-step5-image =
+    .title = Cyfrif wedi'i greu
+
+account-setup-privacy-footnote2 = Dim ond ar eich cyfrifiadur y bydd eich manylion yn cael eu storio'n lleol.
+
+account-setup-selection-help = Ddim yn siŵr beth i'w ddewis?
+
+account-setup-selection-error = Angen cymorth?
+
+account-setup-success-help = Ddim yn siŵr am eich camau nesaf?
+
+account-setup-documentation-help = Dogfennaeth gosod
+
+account-setup-forum-help = Fforwm cefnogi
+
+account-setup-privacy-help = Polisi preifatrwydd
+
+account-setup-getting-started = Cychwyn arni
+
+## Results area
+
+# Variables:
+#  $count (Number) - Number of available protocols.
+account-setup-results-area-title =
+    { $count ->
+        [zero] Ffurfwediadau ar gael
+        [one] Ffurfwediadau ar gael
+        [two] Ffurfwediadau ar gael
+        [few] Ffurfwediadau ar gael
+        [many] Ffurfwediadau ar gael
+       *[other] Ffurfwediadau ar gael
+    }
+
+account-setup-result-imap-description = Cadw eich ffolderi a'ch e-byst wedi'u cydweddu ar eich gweinydd
+
+account-setup-result-pop-description = Cadw eich ffolderi a'ch e-byst ar eich cyfrifiadur
+
+# Note: Exchange, Office365 are the name of products.
+account-setup-result-exchange2-description = Defnyddiwch weinydd Microsoft Exchange neu wasanaethau cwmwl Office365
+
+account-setup-incoming-title = Derbyn
+
+account-setup-outgoing-title = Anfon
+
+account-setup-username-title = Enw Defnyddiwr
+
+account-setup-exchange-title = Gweinydd
+
+account-setup-result-no-encryption = Dim Amgryptiad
+
+account-setup-result-ssl = SSL/TLS
+
+account-setup-result-starttls = STARTTLS
+
+account-setup-result-outgoing-existing = Defnyddio'r gweinydd SMTP anfon cyfredol
+
+# Variables:
+#  $incoming (String): The email/username used to log into the incoming server
+#  $outgoing (String): The email/username used to log into the outgoing server
+account-setup-result-username-different = Derbyn: { $incoming }, Anfon: { $outgoing }
+
+## Error messages
+
+# Note: The reference to "janedoe" (Jane Doe) is the name of an example person. You will want to translate it to whatever example persons would be named in your language. In the example, AD is the name of the Windows domain, and this should usually not be translated.
+account-setup-credentials-incomplete = Methodd y dilysu. Naill ai mae'r manylion a gofnodwyd yn anghywir neu mae angen enw defnyddiwr ar wahân ar gyfer mewngofnodi. Yr enw defnyddiwr hwn fel rheol yw eich mewngofnod parth Windows gyda'r parth neu hebddo (er enghraifft, sianjones neu AD\\sianjones)
+
+account-setup-credentials-wrong = Methodd y dilysu. Gwiriwch yr enw defnyddiwr a'r cyfrinair
+
+account-setup-find-settings-failed = Methodd { -brand-short-name } â dod o hyd i'r gosodiadau ar gyfer eich cyfrif e-bost
+
+account-setup-exchange-config-unverifiable = Nid oedd modd dilysu eich ffurfweddiad. Os yw'ch enw defnyddiwr a'ch cyfrinair yn gywir, mae'n debygol bod gweinyddwr y gweinydd wedi analluogi'r ffurfweddiad a ddewiswyd ar gyfer eich cyfrif. Ceisiwch ddewis protocol arall.
+
+account-setup-provisioner-error = Digwyddodd gwall wrth osod eich cyfrif newydd yn { -brand-short-name }. Ceisiwch osod eich cyfrif gyda'ch manylion, â llaw.
+
+## Manual configuration area
+
+account-setup-manual-config-title = Gosodiadau gweinydd
+
+account-setup-incoming-server-legend = Gweinydd Derbyn
+
+account-setup-protocol-label = Protocol:
+
+account-setup-hostname-label = Enw Gwesteiwr:
+
+account-setup-port-label = Porth:
+    .title = Gosod rhif y porth i 0 ar gyfer awtoganfod
+
+account-setup-auto-description = Bydd { -brand-short-name } yn ceisio awtoganfod meysydd sy'n cael eu gadael yn wag.
+
+account-setup-ssl-label = Diogelwch y cysylltiad:
+
+account-setup-outgoing-server-legend = Gweinydd anfon
+
+## Incoming/Outgoing SSL Authentication options
+
+ssl-autodetect-option = Awtoganfod
+
+ssl-no-authentication-option = Dim dilysiad
+
+ssl-cleartext-password-option = Cyfrinair arferol
+
+ssl-encrypted-password-option = Cyfrinair wedi'i amgryptio
+
+## Incoming/Outgoing SSL options
+
+ssl-noencryption-option = Dim
+
+account-setup-auth-label = Dull dilysu:
+
+account-setup-username-label = Enw defnyddiwr:
+
+account-setup-advanced-setup-button = Ffurfweddiad uwch
+    .accesskey = F
+
+## Warning insecure server dialog
+
+account-setup-insecure-title = Rhybudd!
+
+account-setup-insecure-incoming-title = Gosodiadau derbyn:
+
+account-setup-insecure-outgoing-title = Gosodiadau anfon:
+
+# Variables:
+#  $server (String): The name of the hostname of the server the user was trying to connect to.
+account-setup-warning-cleartext = Nid yw <b>{ $server }</b> yn defnyddio amgryptio.
+
+account-setup-warning-cleartext-details = Nid yw gweinyddion e-bost anniogel yn defnyddio cysylltiadau wedi'u hamgryptio i ddiogelu eich cyfrinair a manylion preifat. Drwy gysylltu â'r gweinydd yma mae modd i chi amlygu eich cyfrinair a manylion preifat.
+
+account-setup-insecure-server-checkbox = Rwy'n deall y peryglon
+    .accesskey = p
+
+account-setup-insecure-description = Mae { -brand-short-name } yn gallu caniatáu i chi estyn eich e-bost drwy ddefnyddio'r ffurfweddiad parod. Er hynny, dylech gysylltu â'ch gweinyddwr neu ddarparwr e-bost ynghylch cysylltiadau anaddas. Gw. <a data-l10n-name="thunderbird-faq-link">Cwestiynau Thunderbird</a> am ragor o wybodaeth.
+
+insecure-dialog-cancel-button = Newid Gosodiadau
+    .accesskey = G
+
+insecure-dialog-confirm-button = Cadarnhau
+    .accesskey = C
+
+## Warning Exchange confirmation dialog
+
+# Variables:
+#  $domain (String): The name of the server where the configuration was found, e.g. rackspace.com.
+exchange-dialog-question = Mae { -brand-short-name } wedi canfod manylion gosod eich cyfrif ar { $domain }. Hoffech chi barhau a chyflwyno'ch manylion?
+
+exchange-dialog-confirm-button = Mewngofnodi
+
+exchange-dialog-cancel-button = Diddymu
+
+## Dismiss account creation dialog
+
+exit-dialog-title = Nid oes Cyfrif E-bost wedi'i Ffurfweddu
+
+exit-dialog-description = Ydych chi'n siŵr eich bod chi am ddiddymu'r broses osod? Mae modd dal i ddefnyddio { -brand-short-name } heb gyfrif e-bost, ond fydd yna ddim llawer o nodweddion ar gael.
+
+account-setup-no-account-checkbox = Defnyddio { -brand-short-name } heb gyfrif e-bost
+    .accesskey = D
+
+exit-dialog-cancel-button = Parhau i Osod
+    .accesskey = P
+
+exit-dialog-confirm-button = Gadael Gosod
+    .accesskey = G
+
+## Alert dialogs
+
+account-setup-creation-error-title = Gwall wrth Greu Cyfrif
+
+account-setup-error-server-exists = Mae'r gweinydd derbyn yn bodoli eisoes.
+
+account-setup-confirm-advanced-title = Cadarnhau Ffurfweddiad Uwch
+
+account-setup-confirm-advanced-description = Bydd y ddeialog hon yn cael ei chau a bydd cyfrif gyda'r gosodiadau cyfredol yn cael ei greu, hyd yn oed os yw'r ffurfweddiad yn anghywir. Hoffech chi barhau?
+
+## Addon installation section
+
+account-setup-addon-install-title = Gosod
+
+account-setup-addon-install-intro = Gall ychwanegyn trydydd parti ganiatáu i chi gael mynediad at eich cyfrif e-bost ar y gweinydd hwn:
+
+account-setup-addon-no-protocol = Yn anffodus nid yw'r gweinydd e-bost hwn yn cefnogi protocolau agored. { account-setup-addon-install-intro }
+
+## Success view
+
+account-setup-settings-button = Gosodiadau cyfrif
+
+account-setup-encryption-button = Amgryptio pen-i-ben
+
+account-setup-signature-button = Ychwanegwch lofnod
+
+account-setup-dictionaries-button = Llwytho geiriadur i lawr
+
+account-setup-address-book-carddav-button = Cysylltu â llyfr cyfeiriadau CardDAV
+
+account-setup-address-book-ldap-button = Cysylltu â llyfr cyfeiriadau LDAP
+
+account-setup-calendar-button = Cysylltu â chalendr pell
+
+account-setup-linked-services-title = Cysylltwch eich gwasanaethau cysylltiedig
+
+account-setup-linked-services-description = Mae { -brand-short-name } wedi canfod gwasanaethau eraill sy'n gysylltiedig â'ch cyfrif e-bost.
+
+account-setup-no-linked-description = Gosod gwasanaethau eraill i gael y gorau o'ch profiad gyda { -brand-short-name }.
+
+# Variables:
+# $count (Number) - The number of address books found during autoconfig.
+account-setup-found-address-books-description =
+    { $count ->
+        [zero] Nid yw { -brand-short-name } wedi canfod unrhyw wasanaeth arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [one] Mae { -brand-short-name } wedi canfod { $count } gwasanaeth arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [two] Mae { -brand-short-name } wedi canfod  { $count } wasanaeth arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [few] Mae { -brand-short-name } wedi canfod  { $count } gwasanaeth arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [many] Mae { -brand-short-name } wedi canfod  { $count } gwasanaeth arall sy'n gysylltiedig â'ch cyfrif e-bost.
+       *[other] Mae { -brand-short-name } wedi canfod  { $count } gwasanaeth arall sy'n gysylltiedig â'ch cyfrif e-bost.
+    }
+
+# Variables:
+# $count (Number) - The number of calendars found during autoconfig.
+account-setup-found-calendars-description =
+    { $count ->
+        [zero] Nid yw { -brand-short-name } wedi canfod  unrhyw galendr arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [one] Mae { -brand-short-name } wedi canfod  { $count } calendr arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [two] Mae { -brand-short-name } wedi canfod  { $count } galendr arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [few] Mae { -brand-short-name } wedi canfod  { $count } chalendr arall sy'n gysylltiedig â'ch cyfrif e-bost.
+        [many] Mae { -brand-short-name } wedi canfod  { $count } chalendr arall sy'n gysylltiedig â'ch cyfrif e-bost.
+       *[other] Mae { -brand-short-name } wedi canfod  { $count } calendr arall sy'n gysylltiedig â'ch cyfrif e-bost.
+    }
+
+account-setup-button-finish = Gorffen
+    .accesskey = G
+
+account-setup-looking-up-address-books = Chwilio drwy lyfrau cyfeiriadau…
+
+account-setup-looking-up-calendars = Chwilio drwy galendrau…
+
+account-setup-address-books-button = Llyfrau Cyfeiriadau
+
+account-setup-calendars-button = Calendrau
+
+account-setup-connect-link = Cysylltu
+
+account-setup-existing-address-book = Wedi'u cysylltu
+    .title = Llyfr cyfeiriadau wedi'u cysylltu'n barod
+
+account-setup-existing-calendar = Wedi'u cysylltu
+    .title = Calendrau wedi'u cysylltu'n barod
+
+account-setup-connect-all-calendars = Cysylltu'r holl galendrau
+
+account-setup-connect-all-address-books = Cysylltu'r holl lyfrau cyfeiriadau
+
+## Calendar synchronization dialog
+
+calendar-dialog-title = Cysylltu calendr
+
+calendar-dialog-cancel-button = Diddymu
+    .accesskey = D
+
+calendar-dialog-confirm-button = Cysylltu
+    .accesskey = C
+
+account-setup-calendar-name-label = Enw
+
+account-setup-calendar-name-input =
+    .placeholder = Calendr
+
+account-setup-calendar-color-label = Lliw
+
+account-setup-calendar-refresh-label = Adnewyddu
+
+account-setup-calendar-refresh-manual = Gyda Llaw
+
+account-setup-calendar-refresh-interval =
+    { $count ->
+        [zero] Byth
+        [one] Pob munud
+        [two] Pob { $count } funud
+        [few] Pob { $count } munud
+        [many] Pob { $count } munud
+       *[other] Pob { $count } munud
+    }
+
+account-setup-calendar-read-only = Darllen yn unig
+    .accesskey = D
+
+account-setup-calendar-show-reminders = Dangos Atgoffwyr
+    .accesskey = A
+
+account-setup-calendar-offline-support = Cefnogaeth All-lein
+    .accesskey = A
diff --git a/l10n-cy/mail/messenger/addressbook/abCardDAVDialog.ftl b/l10n-cy/mail/messenger/addressbook/abCardDAVDialog.ftl
new file mode 100644
index 0000000000..f2f42115dc
--- /dev/null
+++ b/l10n-cy/mail/messenger/addressbook/abCardDAVDialog.ftl
@@ -0,0 +1,26 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+carddav-window-title = Llyfr Cyfeiriadau CardDAV Newydd
+
+carddav-dialog =
+    .buttonlabelaccept = Parhau
+    .buttonaccesskeyaccept = P
+
+carddav-username-label =
+    .value = Enw Defnyddiwr:
+    .accesskey = E
+carddav-location-label =
+    .value = Lleoliad:
+    .accesskey = L
+carddav-location =
+    .default-placeholder = URL neu enw gwesteiwr gweinydd y llyfr cyfeiriadau
+
+carddav-loading = Chwilio am y ffurfweddiad…
+carddav-known-incompatible = Mae'n hysbys bod { $url } yn anghydnaws â { -brand-short-name }.
+carddav-connection-error = Methu cysylltu.
+carddav-none-found = Heb ddod o hyd i lyfrau cyfeiriadau i'w hychwanegu ar gyfer y cyfrif penodedig.
+carddav-already-added = Mae'r holl lyfrau cyfeiriadau ar gyfer y cyfrif penodol eisoes wedi'u hychwanegu.
+
+carddav-available-books = Llyfrau cyfeiriadau sydd ar gael:
diff --git a/l10n-cy/mail/messenger/addressbook/abCardDAVProperties.ftl b/l10n-cy/mail/messenger/addressbook/abCardDAVProperties.ftl
new file mode 100644
index 0000000000..43ee38bd62
--- /dev/null
+++ b/l10n-cy/mail/messenger/addressbook/abCardDAVProperties.ftl
@@ -0,0 +1,41 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+carddav-url-label =
+    .value = URL CardDAV:
+    .accesskey = V
+
+carddav-refreshinterval-label =
+    .label = Cydweddu:
+    .accesskey = C
+
+# Variables:
+#   $minutes (integer) - Number of minutes between address book synchronizations
+carddav-refreshinterval-minutes-value =
+    .label =
+        { $minutes ->
+            [zero] pob munud
+            [one] pob munud
+            [two] pob { $minutes } funud
+            [few] pob { $minutes } munud
+            [many] pob { $minutes } munud
+           *[other] pob { $minutes } munud
+        }
+
+# Variables:
+#   $hours (integer) - Number of hours between address book synchronizations
+carddav-refreshinterval-hours-value =
+    .label =
+        { $hours ->
+            [zero] pob awr
+            [one] pob awr
+            [two] pob { $hours } awr
+            [few] pob { $hours } awr
+            [many] pob { $hours } awr
+           *[other] pob { $hours } awr
+        }
+
+carddav-readonly-label =
+    .label = Darllen yn unig
+    .accesskey = D
diff --git a/l10n-cy/mail/messenger/addressbook/aboutAddressBook.ftl b/l10n-cy/mail/messenger/addressbook/aboutAddressBook.ftl
new file mode 100644
index 0000000000..604ff25291
--- /dev/null
+++ b/l10n-cy/mail/messenger/addressbook/aboutAddressBook.ftl
@@ -0,0 +1,271 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+about-addressbook-title = Llyfr Cyfeiriadau
+
+## Toolbar
+
+about-addressbook-toolbar-new-address-book =
+    .label = Llyfr Cyfeiriadau Newydd
+about-addressbook-toolbar-add-carddav-address-book =
+    .label = Ychwanegu Llyfr Cyfeiriadau CardDAV
+about-addressbook-toolbar-add-ldap-address-book =
+    .label = Ychwanegu Llyfr Cyfeiriadau LDAP
+about-addressbook-toolbar-new-contact =
+    .label = Cysylltiad Newydd
+about-addressbook-toolbar-new-list =
+    .label = Rhestr Newydd
+about-addressbook-toolbar-import =
+    .label = Mewnforio
+
+## Books
+
+all-address-books-row =
+    .title = Pob Llyfr Cyfeiriadau
+all-address-books = Pob Llyfr Cyfeiriadau
+# Variables:
+# $name (String) - The name of the selected book/list.
+# $count (Number) - The number of contacts in the selected book/list.
+about-addressbook-card-count = Cyfanswm y cysylltiadau yn { $name } : { $count }
+# Variables:
+# $count (Number) - The number of contacts in all address books.
+about-addressbook-card-count-all = Cyfanswm y cysylltiadau yn { $name } : { $count }
+about-addressbook-books-context-properties =
+    .label = Priodweddau
+about-addressbook-books-context-edit-list =
+    .label = Golygu'r rhestr
+about-addressbook-books-context-synchronize =
+    .label = Cydweddu
+about-addressbook-books-context-edit =
+    .label = Golygu
+about-addressbook-books-context-print =
+    .label = Argraffu…
+about-addressbook-books-context-export =
+    .label = Allforio…
+about-addressbook-books-context-delete =
+    .label = Dileu
+about-addressbook-books-context-remove =
+    .label = Tynnu
+about-addressbook-books-context-startup-default =
+    .label = Cyfarwyddiadur cychwyn rhagosodedig
+about-addressbook-confirm-delete-book-title = Dileu Llyfr Cyfeiriadau
+# Variables:
+# $name (String) - Name of the address book to be deleted.
+about-addressbook-confirm-delete-book = Ydych chi'n siŵr eich bod chi am ddileu { $name } a'i holl gysylltiadau?
+about-addressbook-confirm-remove-remote-book-title = Dileu Llyfr Cyfeiriadau
+# Variables:
+# $name (String) - Name of the remote address book to be removed.
+about-addressbook-confirm-remove-remote-book = Ydych chi'n siŵr eich bod chi am dynnu { $name }?
+
+## Cards
+
+# Variables:
+# $name (String) - Name of the address book that will be searched.
+about-addressbook-search =
+    .placeholder = Chwilio { $name }
+about-addressbook-search-all =
+    .placeholder = Chwilio'r holl lyfrau cyfeiriadau
+about-addressbook-sort-button2 =
+    .title = Rhestru dewisiadau dangos
+about-addressbook-name-format-display =
+    .label = Dangos Enw
+about-addressbook-name-format-firstlast =
+    .label = Cyntaf Olaf
+about-addressbook-name-format-lastfirst =
+    .label = Olaf, Cyntaf
+about-addressbook-sort-name-ascending =
+    .label = Trefnu yn ôl enw (A > Z)
+about-addressbook-sort-name-descending =
+    .label = Trefnu yn ôl enw (Z > A)
+about-addressbook-sort-email-ascending =
+    .label = Trefnu yn ôl cyfeiriad e-bost (A > Z)
+about-addressbook-sort-email-descending =
+    .label = Trefnu yn ôl cyfeiriad e-bost (Z > A)
+about-addressbook-horizontal-layout =
+    .label = Newid i gynllun llorweddol
+about-addressbook-vertical-layout =
+    .label = Newid i gynllun llorweddol
+about-addressbook-table-layout =
+    .label = Cynllun tabl
+
+## Card column headers
+## Each string is listed here twice, and the values should match.
+
+about-addressbook-column-header-generatedname = Enw
+about-addressbook-column-label-generatedname =
+    .label = { about-addressbook-column-header-generatedname }
+about-addressbook-column-header-emailaddresses = Cyfeiriadau E-bost
+about-addressbook-column-label-emailaddresses =
+    .label = { about-addressbook-column-header-emailaddresses }
+about-addressbook-column-header-nickname = Llysenw
+about-addressbook-column-label-nickname =
+    .label = { about-addressbook-column-header-nickname }
+about-addressbook-column-header-phonenumbers = Rhifau Ffôn
+about-addressbook-column-label-phonenumbers =
+    .label = { about-addressbook-column-header-phonenumbers }
+about-addressbook-column-header-addresses = Cyfeiriadau
+about-addressbook-column-label-addresses =
+    .label = { about-addressbook-column-header-addresses }
+about-addressbook-column-header-title = Teitl
+about-addressbook-column-label-title =
+    .label = { about-addressbook-column-header-title }
+about-addressbook-column-header-department = Adran
+about-addressbook-column-label-department =
+    .label = { about-addressbook-column-header-department }
+about-addressbook-column-header-organization = Corff
+about-addressbook-column-label-organization =
+    .label = { about-addressbook-column-header-organization }
+about-addressbook-column-header-addrbook = Llyfr Cyfeiriadau
+about-addressbook-column-label-addrbook =
+    .label = { about-addressbook-column-header-addrbook }
+about-addressbook-cards-context-write =
+    .label = Ysgrifennu
+about-addressbook-confirm-delete-mixed-title = Dileu Cysylltiadau a Rhestrau
+# Variables:
+# $count (Number) - The number of contacts and lists to be deleted. Always greater than 1.
+about-addressbook-confirm-delete-mixed = Ydych chi'n siŵr eich bod chi am ddileu'r { $count } cysylltiad a'r rhestrau hyn?
+# Variables:
+# $count (Number) - The number of lists to be deleted.
+about-addressbook-confirm-delete-lists-title =
+    { $count ->
+        [zero] Dileu Rhestrau
+        [one] Dileu Rhestr
+        [two] Dileu Rhestr
+        [few] Dileu Rhestr
+        [many] Dileu Rhestr
+       *[other] Dileu Rhestr
+    }
+# Variables:
+# $count (Number) - The number of lists to be deleted.
+# $name (String) - The name of the list to be deleted, if $count is 1.
+about-addressbook-confirm-delete-lists =
+    { $count ->
+        [zero] Ydych chi'n siŵr eich bod eisiau dileu'r cysylltiad { $name }?
+        [one] Ydych chi'n siŵr eich bod eisiau dileu'r cysylltiad { $name }?
+        [two] Ydych chi'n siŵr eich bod eisiau dileu'r cysylltiad { $name }?
+        [few] Ydych chi'n siŵr eich bod eisiau dileu'r cysylltiad { $name }?
+        [many] Ydych chi'n siŵr eich bod eisiau dileu'r cysylltiad { $name }?
+       *[other] Ydych chi'n siŵr eich bod eisiau dileu'r cysylltiad { $name }?
+    }
+# Variables:
+# $count (Number) - The number of contacts to be removed.
+about-addressbook-confirm-remove-contacts-title =
+    { $count ->
+        [zero] Tynnu Cysylltiad
+        [one] Tynnu Cysylltiad
+        [two] Tynnu Cysylltiad
+        [few] Tynnu Cysylltiad
+        [many] Tynnu Cysylltiad
+       *[other] Tynnu Cysylltiad
+    }
+# Variables:
+# $count (Number) - The number of contacts to be removed.
+# $name (String) - The name of the contact to be removed, if $count is 1.
+# $list (String) - The name of the list that contacts will be removed from.
+about-addressbook-confirm-remove-contacts =
+    { $count ->
+        [zero] Ydych chi'n siŵr eich bod eisiau tynnu'r cysylltiad { $name } o { $list }?
+        [one] Ydych chi'n siŵr eich bod eisiau tynnu'r cysylltiad { $name } o { $list }?
+        [two] Ydych chi'n siŵr eich bod eisiau tynnu'r cysylltiad { $name } o { $list }?
+        [few] Ydych chi'n siŵr eich bod eisiau tynnu'r cysylltiad { $name } o { $list }?
+        [many] Ydych chi'n siŵr eich bod eisiau tynnu'r cysylltiad { $name } o { $list }?
+       *[other] Ydych chi'n siŵr eich bod eisiau tynnu'r cysylltiad { $name } o { $list }?
+    }
+# Variables:
+# $count (Number) - The number of contacts to be deleted.
+about-addressbook-confirm-delete-contacts-title =
+    { $count ->
+        [zero] Dileu Cysylltiadau
+        [one] Dileu Cysylltiad
+        [two] Dileu Cysylltiad
+        [few] Dileu Cysylltiad
+        [many] Dileu Cysylltiad
+       *[other] Dileu Cysylltiad
+    }
+# Variables:
+# $count (Number) - The number of contacts to be deleted.
+# $name (String) - The name of the contact to be deleted, if $count is 1.
+about-addressbook-confirm-delete-contacts =
+    { $count ->
+        [zero] Ydych chi'n siŵr eich bod chi am ddileu'r { $count } cysylltiad yma?
+        [one] Ydych chi'n siŵr eich bod chi am ddileu'r { $count } cysylltiad yma?
+        [two] Ydych chi'n siŵr eich bod chi am ddileu'r { $count } cysylltiad yma?
+        [few] Ydych chi'n siŵr eich bod chi am ddileu'r { $count } cysylltiad yma?
+        [many] Ydych chi'n siŵr eich bod chi am ddileu'r { $count } cysylltiad yma?
+       *[other] Ydych chi'n siŵr eich bod chi am ddileu'r { $count } cysylltiad yma?
+    }
+
+## Card list placeholder
+## Shown when there are no cards in the list
+
+about-addressbook-placeholder-empty-book = Dim cysylltiadau ar gael
+about-addressbook-placeholder-new-contact = Cysylltiad Newydd
+about-addressbook-placeholder-search-only = Dim ond ar ôl chwilio mae'r llyfr cyfeiriadau hwn yn dangos cysylltiadau
+about-addressbook-placeholder-searching = Yn chwilio…
+about-addressbook-placeholder-no-search-results = Heb ganfod cysylltiadau
+
+## Details
+
+# Variables:
+# $count (Number) - The number of selected items (will never be fewer than two)
+about-addressbook-selection-mixed-header = Mae { $count } o gysylltiadau a rhestrau wedi'u dewis
+# Variables:
+# $count (Number) - The number of selected contacts
+about-addressbook-selection-contacts-header = Mae { $count } cysylltiad wedi'u dewis
+# Variables:
+# $count (Number) - The number of selected lists
+about-addressbook-selection-lists-header = Mae { $count } rhestr wedi'u dewis
+about-addressbook-details-edit-photo =
+    .title = Golygu llun cyswllt
+about-addressbook-new-contact-header = Cysylltiad Newydd
+about-addressbook-prefer-display-name = Dewis enw dangos o flaen pennyn neges
+about-addressbook-write-action-button = Ysgrifennu
+about-addressbook-event-action-button = Digwyddiad
+about-addressbook-search-action-button = Chwilio
+about-addressbook-new-list-action-button = Rhestr Newydd
+about-addressbook-begin-edit-contact-button = Golygu
+about-addressbook-delete-edit-contact-button = Dileu
+about-addressbook-cancel-edit-contact-button = Diddymu
+about-addressbook-save-edit-contact-button = Cadw
+about-addressbook-add-contact-to = Ychwanegu at:
+about-addressbook-details-email-addresses-header = Cyfeiriadau E-bost
+about-addressbook-details-phone-numbers-header = Rhifau Ffôn
+about-addressbook-details-addresses-header = Cyfeiriadau
+about-addressbook-details-notes-header = Nodiadau
+about-addressbook-details-impp-header = Negesu Chwim
+about-addressbook-details-websites-header = Gwefannau
+about-addressbook-details-other-info-header = Manylion Eraill
+about-addressbook-entry-type-work = Gwaith
+about-addressbook-entry-type-home = Cartref
+about-addressbook-entry-type-fax = Ffacs
+# Or "Mobile"
+about-addressbook-entry-type-cell = Symudol
+about-addressbook-entry-type-pager = Swnyn
+about-addressbook-entry-name-birthday = Pen-blwydd
+about-addressbook-entry-name-anniversary = Dathliad
+about-addressbook-entry-name-title = Teitl
+about-addressbook-entry-name-role = Rôl
+about-addressbook-entry-name-organization = Corff
+about-addressbook-entry-name-website = Gwefan
+about-addressbook-entry-name-time-zone = Cylch Amser
+about-addressbook-entry-name-custom1 = Cyfaddasu 1
+about-addressbook-entry-name-custom2 = Cyfaddasu 2
+about-addressbook-entry-name-custom3 = Cyfaddasu 3
+about-addressbook-entry-name-custom4 = Cyfaddasu 4
+about-addressbook-unsaved-changes-prompt-title = Newidiadau heb eu Cadw
+about-addressbook-unsaved-changes-prompt = Ydych chi am gadw'ch newidiadau cyn gadael y wedd golygu?
+
+# Photo dialog
+
+about-addressbook-photo-drop-target = Gollwng neu gludo llun yma, neu glicio i ddewis ffeil.
+about-addressbook-photo-drop-loading = Yn llwytho llun…
+about-addressbook-photo-drop-error = Wedi methu llwytho llun.
+about-addressbook-photo-filepicker-title = Dewiswch ffeil delwedd
+about-addressbook-photo-discard = Dileu'r llun presennol
+about-addressbook-photo-cancel = Diddymu
+about-addressbook-photo-save = Cadw
+
+# Keyboard shortcuts
+
+about-addressbook-new-contact-key = N
diff --git a/l10n-cy/mail/messenger/addressbook/fieldMapImport.ftl b/l10n-cy/mail/messenger/addressbook/fieldMapImport.ftl
new file mode 100644
index 0000000000..bedd9e6bba
--- /dev/null
+++ b/l10n-cy/mail/messenger/addressbook/fieldMapImport.ftl
@@ -0,0 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import-ab-csv-dialog-title = Mewnforio Llyfr Cyfeiriadau o Ffeil Testun
+
+#   $recordNumber (Number) - The current record number of the preview data.
+import-ab-csv-preview-record-number = Rhagolwg o'r mewnforio data ar gyfer cofnod { $recordNumber }
+
+import-ab-csv-dialog =
+    .buttonlabelaccept = Mewnforio
+    .buttonaccesskeyaccept = M
diff --git a/l10n-cy/mail/messenger/addressbook/vcard.ftl b/l10n-cy/mail/messenger/addressbook/vcard.ftl
new file mode 100644
index 0000000000..4aa0025299
--- /dev/null
+++ b/l10n-cy/mail/messenger/addressbook/vcard.ftl
@@ -0,0 +1,138 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+# Display Name
+
+vcard-displayname = Enw dangos
+vcard-displayname-placeholder =
+    .placeholder = { vcard-displayname }
+
+# Type selection
+
+vcard-entry-type-label = Math
+vcard-entry-type-home = Cartref
+vcard-entry-type-work = Gwaith
+vcard-entry-type-none = Dim
+vcard-entry-type-custom = Cyfaddas
+
+# N vCard field
+
+vcard-name-header = Enw
+vcard-n-prefix = Rhagddodiad
+vcard-n-add-prefix =
+    .title = Ychwanegu rhagddodiad
+vcard-n-firstname = Enw cyntaf
+vcard-n-add-firstname =
+    .title = Ychwanegu enw cyntaf
+vcard-n-middlename = Enw canol
+vcard-n-add-middlename =
+    .title = Ychwanegu enw canol
+vcard-n-lastname = Enw olaf
+vcard-n-add-lastname =
+    .title = Ychwanegu enw olaf
+vcard-n-suffix = Ôl-ddodiad
+vcard-n-add-suffix =
+    .title = Ychwanegu ôl-ddodiad
+
+# Nickname
+
+vcard-nickname = Llysenw
+
+# Email vCard field
+
+vcard-email-header = Cyfeiriadau E-bost
+vcard-email-add = Ychwanegu cyfeiriad e-bost
+vcard-email-label = Cyfeiriad e-bost
+vcard-primary-email-label = Rhagosodiad
+
+# URL vCard field
+
+vcard-url-header = Gwefannau
+vcard-url-add = Ychwanegu gwefan
+vcard-url-label = Gwefan
+
+# Tel vCard field
+
+vcard-tel-header = Rhifau Ffôn
+vcard-tel-add = Ychwanegu rhif ffôn
+vcard-tel-label = Rhif ffôn
+# Or "Mobile"
+vcard-entry-type-cell = Cell
+vcard-entry-type-fax = Ffacs
+vcard-entry-type-pager = Swnyn
+
+# TZ vCard field
+
+vcard-tz-header = Cylch Amser
+vcard-tz-add = Ychwanegu cylch amser
+
+# IMPP vCard field
+
+vcard-impp2-header = Negesu Chwim
+vcard-impp-add = Ychwanegu cyfrif sgwrsio
+vcard-impp-label = Cyfrif sgwrsio
+vcard-impp-select = Protocol
+vcard-impp-option-other = Arall
+vcard-impp-input-label = URI
+vcard-impp-input-title = URI ar gyfer negeseuon chwim
+
+# BDAY and ANNIVERSARY vCard field
+
+vcard-bday-anniversary-header = Dyddiadau Arbennig
+vcard-bday-anniversary-add = Ychwanegu dyddiad arbennig
+vcard-bday-label = Pen-blwydd
+vcard-anniversary-label = Dathliad
+vcard-date-day = Diwrnod
+vcard-date-month = Mis
+vcard-date-year = Blwyddyn
+
+# ADR vCard field
+
+vcard-adr-header = Cyfeiriadau
+vcard-adr-add = Ychwanegu cyfeiriad
+vcard-adr-label = Cyfeiriadau
+vcard-adr-delivery-label = Label dosbarthu
+vcard-adr-street = Cyfeiriad stryd
+# Or "Locality"
+vcard-adr-locality = Tref/Dinas
+# Or "Region"
+vcard-adr-region = Sir/Talaith:
+# The term "ZIP code" only applies in USA. Most locales should use "Postal code" only.
+vcard-adr-code = Cod Post/ZIP:
+vcard-adr-country = Gwlad
+
+# NOTE vCard field
+
+vcard-note-header = Nodiadau
+vcard-note-add = Ychwanegu nodyn
+
+# TITLE, ROLE and ORGANIZATION vCard fields
+
+vcard-org-header = Adeiladau Sefydliadol
+vcard-org-add = Ychwanegu adeiladau sefydliadol
+vcard-org-title = Teitl
+vcard-org-title-input =
+    .title = Safle neu swydd
+    .placeholder = Tetl swydd
+vcard-org-role = Rôl
+vcard-org-role-input =
+    .title = Swyddogaeth neu ran yn cael ei chwarae mewn sefyllfa benodol
+    .placeholder = Rôl mewn project
+vcard-org-org = Corff
+vcard-org-org-input =
+    .title = Enw corfforaethol
+    .placeholder = Enw cwmni
+vcard-org-org-unit = Adran
+vcard-org-org-unit-input =
+    .title = Enw uned corfforaethol
+    .placeholder = Adran
+
+# Custom properties
+
+vcard-custom-header = Priodweddau Cyfaddas
+vcard-custom-add = Ychwanegu priodweddau cyfaddas
+vcard-remove-button-title =
+    .title = Tynnu
+vcard-remove-button = Tynnu
diff --git a/l10n-cy/mail/messenger/appmenu.ftl b/l10n-cy/mail/messenger/appmenu.ftl
new file mode 100644
index 0000000000..c7273dff41
--- /dev/null
+++ b/l10n-cy/mail/messenger/appmenu.ftl
@@ -0,0 +1,208 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Sync
+
+appmenu-sync-panel-title =
+    .title = Sync
+appmenu-signin-panel =
+    .label = Mewngofnodwch i Sync
+    .accesskey = S
+appmenu-sync-sync =
+    .value = Cydweddu Cyfrif
+    .accesskey = C
+appmenu-sync-manage =
+    .value = Rheoli Cyfrif
+    .accesskey = R
+appmenu-sync-account =
+    .value = example@example.com
+appmenu-sync-now =
+    .label = Cydweddu Nawr
+    .accesskey = N
+appmenu-sync-settings =
+    .label = Gosodiadau Sync
+    .accesskey = G
+appmenu-sync-sign-out =
+    .label = Allgofnodi…
+    .accesskey = A
+
+## New Account
+
+appmenu-new-account-panel-title =
+    .title = Cyfrif Newydd
+appmenu-new-account-panel =
+    .label = Cyfrif Newydd
+    .accesskey = C
+appmenu-create-new-mail-account =
+    .label = Cael E-bost Newydd
+    .accesskey = E
+appmenu-new-mail-account =
+    .label = E-bost Cyfredol
+    .accesskey = b
+appmenu-new-calendar =
+    .label = Calendr
+    .accesskey = a
+appmenu-new-chat-account =
+    .label = Sgwrsio
+    .accesskey = S
+appmenu-new-feed =
+    .label = Llif
+    .accesskey = L
+appmenu-new-newsgroup =
+    .label = Grŵp Newyddion
+    .accesskey = N
+
+## New Account / Address Book
+
+appmenu-newab-panel-title =
+    .title = Llyfr Cyfeiriadau Newydd
+appmenu-newab-panel =
+    .label = Llyfr Cyfeiriadau Newydd
+    .accesskey = L
+appmenu-new-addressbook =
+    .label = Llyfrau Cyfeiriadau Lleol
+    .accesskey = C
+appmenu-new-carddav =
+    .label = Llyfr Cyfeiriadau CardDAV…
+    .accesskey = D
+appmenu-new-ldap =
+    .label = Llyfr Cyfeiriadau LDAP
+    .accesskey = D
+
+## Create
+
+appmenu-create-panel-title =
+    .title = Creu
+appmenu-create-panel =
+    .label = Creu
+    .accesskey = C
+appmenu-create-message =
+    .label = Neges
+    .accesskey = N
+appmenu-create-event =
+    .label = Digwyddiad
+    .accesskey = D
+appmenu-create-task =
+    .label = Tasg
+    .accesskey = T
+appmenu-create-contact =
+    .label = Cysylltiad
+    .accesskey = y
+
+## Open
+
+appmenu-open-file-panel =
+    .label = Agor o Ffeil
+    .accesskey = A
+appmenu-open-file-panel-title =
+    .title = Agor o Ffeil
+appmenu-open-message =
+    .label = Neges…
+    .accesskey = N
+appmenu-open-calendar =
+    .label = Calendr…
+    .accesskey = C
+
+## View / Layout
+
+appmenu-view-panel-title =
+    .title = Golwg
+appmenu-view-panel =
+    .label = Golwg
+    .accesskey = G
+appmenu-font-size-value = Maint Ffont
+appmenu-mail-uidensity-value = Dwysedd
+appmenu-uidensity-compact =
+    .tooltiptext = Cryno
+appmenu-uidensity-default =
+    .tooltiptext = Rhagosodedig
+appmenu-uidensity-relaxed =
+    .tooltiptext = Llaes
+appmenuitem-font-size-enlarge =
+    .tooltiptext = Cynyddu Maint Ffont
+appmenuitem-font-size-reduce =
+    .tooltiptext = Lleihau Maint Ffont
+# Variables:
+# $size (String) - The current font size.
+appmenuitem-font-size-reset =
+    .label = { $size }px
+    .tooltiptext = Ailosod Maint Ffont
+
+## Tools
+
+appmenu-tools-panel-title =
+    .title = Offer
+appmenu-tools-panel =
+    .label = Offer
+    .accesskey = O
+appmenu-tools-import =
+    .label = Mewnforio
+    .accesskey = M
+appmenu-tools-export =
+    .label = Allforio
+    .accesskey = A
+appmenu-tools-message-search =
+    .label = Chwilio drwy'r Negeseuon
+    .accesskey = C
+appmenu-tools-message-filters =
+    .label = Hidlau Negeseuon
+    .accesskey = H
+appmenu-tools-download-manager =
+    .label = Rheolwr Llwythi
+    .accesskey = R
+appmenu-tools-activity-manager =
+    .label = Rheolwr Gweithgaredd
+    .accesskey = R
+appmenu-tools-dev-tools =
+    .label = Offer Datblygwyr
+    .accesskey = O
+
+## Help
+
+appmenu-help-panel-title =
+    .title = Cymorth
+appmenu-help-get-help =
+    .label = Derbyn Cymorth
+    .accesskey = D
+appmenu-help-explore-features =
+    .label = Edrych ar y Nodweddion
+    .accesskey = E
+appmenu-help-shortcuts =
+    .label = Llwybrau Byr Bysellfwrdd
+    .accesskey = L
+appmenu-help-get-involved =
+    .label = Ymunwch
+    .accesskey = Y
+appmenu-help-donation =
+    .label = Gwnewch Rodd
+    .accesskey = G
+appmenu-help-share-feedback =
+    .label = Rhannwch Syniadau ac Adborth…
+    .accesskey = R
+appmenu-help-enter-troubleshoot-mode2 =
+    .label = Y Modd Datrys Problemau…
+    .accesskey = M
+appmenu-help-exit-troubleshoot-mode2 =
+    .label = Diffodd y Modd Dartrys Problemau
+    .accesskey = D
+appmenu-help-troubleshooting-info =
+    .label = Gwybodaeth am Ddatrys Problemau
+    .accesskey = G
+appmenu-help-about-product =
+    .label = Ynghylch { -brand-short-name }
+    .accesskey = Y
+
+## Application Update
+
+appmenuitem-banner-update-downloading =
+    .label = Llwytho diweddariad { -brand-shorter-name } i lawr
+appmenuitem-banner-update-available =
+    .label = Mae diweddariad ar gael — llwytho i lawr nawr
+appmenuitem-banner-update-manual =
+    .label = Mae diweddariad ar gael — llwytho i lawr nawr
+appmenuitem-banner-update-unsupported =
+    .label = Methu diweddaru — mae'r system yn anghydnaws
+appmenuitem-banner-update-restart =
+    .label = Mae diweddariad ar gael — ailgychwyn nawr
diff --git a/l10n-cy/mail/messenger/chat-verifySession.ftl b/l10n-cy/mail/messenger/chat-verifySession.ftl
new file mode 100644
index 0000000000..b1d162960b
--- /dev/null
+++ b/l10n-cy/mail/messenger/chat-verifySession.ftl
@@ -0,0 +1,17 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+verify-window-title = Gwirio Hunaniaeth
+
+# Variables:
+#   $subject (String) - a human readable identifier for the other side of the verification flow.
+verify-window-subject-title = Gwirio Hunaniaeth { $subject }
+
+verify-dialog =
+    .buttonlabelaccept = Cydweddiad
+    .buttonaccesskeyaccept = C
+    .buttonlabelextra2 = Dim Cyweddiad
+    .buttonaccesskeyextra2 = D
+
+challenge-label = Gwiriwch fod y llinyn sy'n cael ei ddangos yn cyd-fynd â'r hyn sy'n cael ei ddangos ar y pen draw.
diff --git a/l10n-cy/mail/messenger/chat.ftl b/l10n-cy/mail/messenger/chat.ftl
new file mode 100644
index 0000000000..035b730427
--- /dev/null
+++ b/l10n-cy/mail/messenger/chat.ftl
@@ -0,0 +1,47 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+chat-joining-chat-icon2 =
+    .alt = Ymuno â sgwrs
+
+chat-left-chat-icon2 =
+    .alt = Gadael sgwrs
+
+chat-participant-owner-role-icon2 =
+    .alt = Perchennog
+
+chat-participant-administrator-role-icon2 =
+    .alt = Gweinyddwr
+
+chat-participant-moderator-role-icon2 =
+    .alt = Cymedrolwr
+
+chat-participant-voiced-role-icon2 =
+    .alt = Gall gyfranogwr anfon negeseuon
+
+chat-verify-identity =
+    .label = Gwirio Hunaniaeth
+    .accesskey = G
+
+chat-identity-verified =
+    .label = Hunaniaeth wedi'i gwirio eisoes
+
+chat-buddy-identity-status = Ymddiriedaeth Amgryptio
+chat-buddy-identity-status-verified = Gwiriwyd
+chat-buddy-identity-status-unverified = Heb ei wirio
+
+## Conversation invite notification box
+
+# This string appears in a notification bar at the top of the Contacts window
+# when someone invited the user to a multi user chat conversation, to request
+# the user to confirm they want to join the chat.
+# Variables:
+#   $conversation (String) - Name of the conversation the user is invited to.
+chat-conv-invite-label = Rydych wedi'ch gwahodd i sgwrsio yn { $conversation }
+chat-conv-invite-accept =
+    .label = Derbyn
+    .accesskey = D
+chat-conv-invite-deny =
+    .label = Gwrthod
+    .accesskey = G
diff --git a/l10n-cy/mail/messenger/compactFoldersDialog.ftl b/l10n-cy/mail/messenger/compactFoldersDialog.ftl
new file mode 100644
index 0000000000..15caffb43a
--- /dev/null
+++ b/l10n-cy/mail/messenger/compactFoldersDialog.ftl
@@ -0,0 +1,24 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+compact-dialog-window =
+    .title = Cywasgu ffolderi
+    .style = width: 50em;
+
+compact-dialog =
+    .buttonlabelaccept = Cywasgu nawr
+    .buttonaccesskeyaccept = C
+    .buttonlabelcancel = Atgoffa fi yn hwyrach
+    .buttonaccesskeycancel = A
+    .buttonlabelextra1 = Dysgu rhagor…
+    .buttonaccesskeyextra1 = D
+
+# Variables:
+#  $data (String): The amount of space to be freed, formatted byte, MB, GB, etc., based on the size.
+compact-dialog-message = Mae angen i { -brand-short-name } wneud gwaith cynnal a chadw ffeiliau yn rheolaidd i wella perfformiad eich ffolderi e-bost. Bydd hyn yn adfer { $data } o ofod disg heb newid eich negeseuon. I adael i { -brand-short-name } wneud hyn yn awtomatig yn y dyfodol heb ofyn, ticiwch y blwch isod cyn dewis ‘{ compact-dialog.buttonlabelaccept }’.
+
+compact-dialog-never-ask-checkbox =
+    .label = Cywasgu ffolderi yn awtomatig yn y dyfodol
+    .accesskey = a
+
diff --git a/l10n-cy/mail/messenger/exportDialog.ftl b/l10n-cy/mail/messenger/exportDialog.ftl
new file mode 100644
index 0000000000..0f8bd587a4
--- /dev/null
+++ b/l10n-cy/mail/messenger/exportDialog.ftl
@@ -0,0 +1,22 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+export-dialog-brand-name = { -brand-product-name }
+
+export-dialog-title = Allforio
+
+export-dialog =
+    .buttonlabelaccept = Nesaf
+
+export-dialog-button-finish = Gorffen
+
+export-dialog-file-picker = Allforio i ffeil zip
+
+export-dialog-description1 = Allforio cyfrifon e-bost, negeseuon e-bost, llyfrau cyfeiriadau a dewisiadau i ffeil zip.
+
+export-dialog-desc2 = Pan fydd angen, gallwch fewnforio'r ffeil zip i adfer eich proffil.
+
+export-dialog-exporting = Yn allforio…
+
+export-dialog-exported = Wedi'i allforio!
diff --git a/l10n-cy/mail/messenger/extensions/popup.ftl b/l10n-cy/mail/messenger/extensions/popup.ftl
new file mode 100644
index 0000000000..4b400f2ab7
--- /dev/null
+++ b/l10n-cy/mail/messenger/extensions/popup.ftl
@@ -0,0 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Variables:
+#   $title (String): the title of the popup window
+extension-popup-title =
+    { PLATFORM() ->
+        [macos] { $title }
+       *[other] { $title } - { -brand-full-name }
+    }
+extension-popup-default-title = { -brand-full-name }
diff --git a/l10n-cy/mail/messenger/importDialog.ftl b/l10n-cy/mail/messenger/importDialog.ftl
new file mode 100644
index 0000000000..fe71f6fa23
--- /dev/null
+++ b/l10n-cy/mail/messenger/importDialog.ftl
@@ -0,0 +1,30 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Short name of the import module
+thunderbird-import-name = Thunderbird
+
+# Description of the import module
+thunderbird-import-description = Mewnforio e-bost o gyfeiriadur proffil Thunderbird.
+
+import-from-thunderbird-zip =
+    .label = Thunderbird (copi wrth gefn o broffil wedi'i allforio; ffeil sip llai na 2GB)
+    .accesskey = T
+
+import-from-thunderbird-dir =
+    .label = Thunderbird (ffolder proffil)
+    .accesskey = p
+
+import-select-profile-zip = Dewiswch gyfeiriadur proffil wedi'i zipio
+
+import-select-profile-dir = Dewis cyfeiriadur proffil
+
+zip-file-too-big-title = Mae'r Ffeil Zip yn Rhy Fawr
+
+zip-file-too-big-message = Mae'r ffeil zip a ddewiswyd yn fwy na 2GB. Echdynnwch hi'n gyntaf, yna ei mewnforio o'r ffolder cafodd ei hechdynnu.
+
+wizardpage-failed =
+    .label = Methodd y Mewnforio
+
+wizardpage-failed-message = Methodd y mewnforio yn annisgwyl, efallai y bydd mwy o wybodaeth ar gael yn y Consol Gwallau.
diff --git a/l10n-cy/mail/messenger/mailWidgets.ftl b/l10n-cy/mail/messenger/mailWidgets.ftl
new file mode 100644
index 0000000000..38ed76eb85
--- /dev/null
+++ b/l10n-cy/mail/messenger/mailWidgets.ftl
@@ -0,0 +1,15 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+apply-current-view-to-menu =
+    .label = Gosod yr olwg gyfredol i…
+
+threadpane-apply-changes-prompt-title = Gosod y Newidiadau?
+# Variables:
+#  $name (String): The name of the folder to apply to.
+threadpane-apply-changes-prompt-no-children-text = Gosod golwg y ffolder gyfredol i { $name }?
+# Variables:
+#  $name (String): The name of the folder to apply to.
+threadpane-apply-changes-prompt-with-children-text = Gosod golwg y ffolder gyfredol i { $name } a'i phlant?
+
diff --git a/l10n-cy/mail/messenger/menubar.ftl b/l10n-cy/mail/messenger/menubar.ftl
new file mode 100644
index 0000000000..6b3e688ec2
--- /dev/null
+++ b/l10n-cy/mail/messenger/menubar.ftl
@@ -0,0 +1,160 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+toolbar-context-menu-menu-bar =
+    .toolbarname = Bar Dewislen
+    .accesskey = D
+
+## Tools Menu
+
+menu-tools-settings =
+    .label = Gosodiadau
+    .accesskey = G
+
+menu-addons-and-themes =
+    .label = Ychwanegion a Themâu
+    .accesskey = Y
+
+## Help Menu
+
+menu-help-help-title =
+    .label = Cymorth
+    .accesskey = C
+
+menu-help-get-help =
+    .label = Derbyn Cymorth
+    .accesskey = D
+
+menu-help-explore-features =
+    .label = Edrych ar y Nodweddion
+    .accesskey = E
+
+menu-help-shortcuts =
+    .label = Llwybrau Byr Bysellfwrdd
+    .accesskey = L
+
+menu-help-get-involved =
+    .label = Ymunwch
+    .accesskey = Y
+
+menu-help-donation =
+    .label = Gwnewch Rodd
+    .accesskey = G
+
+menu-help-share-feedback =
+    .label = Rhannwch Syniadau ac Adborth…
+    .accesskey = R
+
+menu-help-enter-troubleshoot-mode =
+    .label = Y Modd Datrys Problemau…
+    .accesskey = M
+
+menu-help-exit-troubleshoot-mode =
+    .label = Diffodd y Modd Dartrys Problemau
+    .accesskey = D
+
+menu-help-more-troubleshooting-info =
+    .label = Rhagor o Wybodaeth Datrys Problemau
+    .accesskey = R
+
+menu-help-troubleshooting-info =
+    .label = Gwybodaeth am Ddatrys Problemau
+    .accesskey = G
+
+menu-help-about-product =
+    .label = Ynghylch { -brand-short-name }
+    .accesskey = Y
+
+# These menu-quit strings are only used on Windows and Linux.
+menu-quit =
+    .label =
+        { PLATFORM() ->
+            [windows] Gadael
+           *[other] Gadael
+        }
+    .accesskey =
+        { PLATFORM() ->
+            [windows] G
+           *[other] G
+        }
+
+# This menu-quit-mac string is only used on macOS.
+menu-quit-mac =
+    .label = Gadael { -brand-shorter-name }
+
+quit-app-shortcut =
+    .key = G
+
+## Mail Toolbar
+
+toolbar-junk-button =
+    .label = Sbwriel
+    .tooltiptext = Marcio'r negeseuon hyn fel sbwriel
+toolbar-not-junk-button =
+    .label = Nid Sbwriel
+    .tooltiptext = Marcio'r negeseuon hyn fel nid sbwriel
+toolbar-delete-button =
+    .label = Dileu
+    .tooltiptext = Dileu'r negeseuon neu ffolderi hyn
+toolbar-undelete-button =
+    .label = Dad-ddileu
+    .tooltiptext = Dad-ddileu'r negeseuon hyn
+
+## View
+
+menu-view-repair-text-encoding =
+    .label = Trwsio Amgodio Testun
+    .accesskey = T
+
+## View / Layout
+
+menu-font-size-label =
+    .label = Maint Ffont
+    .accesskey = M
+
+menuitem-font-size-enlarge =
+    .label = Cynyddu Maint Ffont
+    .accesskey = F
+
+menuitem-font-size-reduce =
+    .label = Lleihau Maint Ffont
+    .accesskey = L
+
+menuitem-font-size-reset =
+    .label = Ailosod Maint Ffont
+    .accesskey = A
+
+mail-uidensity-label =
+    .label = Dwysedd
+    .accesskey = D
+
+mail-uidensity-compact =
+    .label = Cryno
+    .accesskey = C
+
+mail-uidensity-normal =
+    .label = Arferol
+    .accesskey = A
+
+mail-uidensity-touch =
+    .label = Cyffwrdd
+    .accesskey = y
+
+mail-uidensity-default =
+    .label = Rhagosodiad
+    .accesskey = R
+
+mail-uidensity-relaxed =
+    .label = Llaes
+    .accesskey = L
+
+menu-spaces-toolbar-button =
+    .label = Bar Offer Mannau
+    .accesskey = B
+
+## File
+
+file-new-newsgroup-account =
+    .label = Cyfrif Grŵp Newyddion…
+    .accesskey = N
diff --git a/l10n-cy/mail/messenger/messageheader/headerFields.ftl b/l10n-cy/mail/messenger/messageheader/headerFields.ftl
new file mode 100644
index 0000000000..95e2b34275
--- /dev/null
+++ b/l10n-cy/mail/messenger/messageheader/headerFields.ftl
@@ -0,0 +1,71 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Header lists
+
+message-header-to-list-name = At
+
+message-header-from-list-name = Oddi wrth
+
+message-header-sender-list-name = Anfonwr
+
+message-header-reply-to-list-name = Ateb i
+
+message-header-cc-list-name = Cc
+
+message-header-bcc-list-name = Bcc
+
+message-header-newsgroups-list-name = Grwpiau Newyddion
+
+message-header-tags-list-name = Tagiau
+
+## Other message headers.
+## The field-separator is for screen readers to separate the field name from the field value.
+
+message-header-author-field = Awdur<span data-l10n-name="field-separator">:</span>
+
+message-header-organization-field = Corff<span data-l10n-name="field-separator">:</span>
+
+message-header-subject-field = Pwnc<span data-l10n-name="field-separator">:</span>
+
+message-header-followup-to-field = Dilynol i<span data-l10n-name="field-separator">:</span>
+
+
+message-header-date-field = Dyddiad<span data-l10n-name="field-separator">:</span>
+
+message-header-user-agent-field = Asiant defnyddiwr<span data-l10n-name="field-separator">:</span>
+
+message-header-references-field = Cyfeiriadau<span data-l10n-name="field-separator">:</span>
+
+message-header-message-id-field = ID Neges<span data-l10n-name="field-separator">:</span>
+
+message-header-in-reply-to-field = Wrth ateb i<span data-l10n-name="field-separator">:</span>
+
+message-header-website-field = Gwefan<span data-l10n-name="field-separator">:</span>
+
+# An additional email header field that the user has chosen to display. Unlike
+# the other headers, the name of this header is not expected to be localised
+# because it is generated from the raw field name found in the email header.
+#   $fieldName (String) - The field name.
+message-header-custom-field = { $fieldName }<span data-l10n-name="field-separator">:</span>
+
+##
+
+message-header-address-in-address-book-icon2 =
+    .alt = Yn y Llyfr Cyfeiriadau
+
+message-header-address-not-in-address-book-icon2 =
+    .alt = Ddim yn y Llyfr Cyfeiriadau
+
+message-header-address-not-in-address-book-button =
+    .title = Cadw'r cyfeiriad hwn i'r Llyfr Cyfeiriadau
+
+message-header-address-in-address-book-button =
+    .title = Golygu cysylltiad
+
+message-header-field-show-more = Rhagor
+    .title = Dangos pob derbynnydd
+
+message-ids-field-show-all = Dangos y cyfan
diff --git a/l10n-cy/mail/messenger/messenger.ftl b/l10n-cy/mail/messenger/messenger.ftl
new file mode 100644
index 0000000000..24cd5884ab
--- /dev/null
+++ b/l10n-cy/mail/messenger/messenger.ftl
@@ -0,0 +1,352 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Window controls
+
+messenger-window-minimize-button =
+    .tooltiptext = Lleihau
+messenger-window-maximize-button =
+    .tooltiptext = Mwyhau
+messenger-window-restore-down-button =
+    .tooltiptext = Adfer i Lawr
+messenger-window-close-button =
+    .tooltiptext = Cau
+
+# Variables:
+# $count (Number) - Number of unread messages.
+unread-messages-os-tooltip =
+    { $count ->
+        [zero] 0 negeseuon heb eu darllen
+        [one] 1 neges heb ei darllen
+        [two] { $count } neges heb eu darllen
+        [few] { $count } neges heb eu darllen
+        [many] { $count } neges heb eu darllen
+       *[other] { $count } neges heb eu darllen
+    }
+
+about-rights-notification-text = Mae { -brand-short-name } yn feddalwedd cod agored am ddim, wedi'i adeiladu gan gymuned o filoedd o bob cwr o'r byd.
+
+## Content tabs
+
+content-tab-page-loading-icon =
+    .alt = Mae'r dudalen yn llwytho
+content-tab-security-high-icon =
+    .alt = Mae'r cysylltiad yn ddiogel
+content-tab-security-broken-icon =
+    .alt = Nid yw'r cysylltiad yn ddiogel
+
+## Toolbar
+
+addons-and-themes-toolbarbutton =
+    .label = Ychwanegion a Themâu
+    .tooltiptext = Rheoli eich ychwanegion
+
+quick-filter-toolbarbutton =
+    .label = Hidl Cyflym
+    .tooltiptext = Hidlo negeseuon
+
+redirect-msg-button =
+    .label = Ailgyfeirio
+    .tooltiptext = Ailgyfeirio'r neges hon
+
+## Folder Pane
+
+folder-pane-toolbar =
+    .toolbarname = Bar Offer Paen Ffolder
+    .accesskey = P
+
+folder-pane-toolbar-options-button =
+    .tooltiptext = Opsiynau Ffolder Paen
+
+folder-pane-header-label = Ffolderi
+
+## Folder Toolbar Header Popup
+
+folder-toolbar-hide-toolbar-toolbarbutton =
+    .label = Cuddio'r Bar Offer
+    .accesskey = C
+
+show-all-folders-label =
+    .label = Pob Ffolder
+    .accesskey = P
+
+show-unread-folders-label =
+    .label = Ffolderi Heb eu Darllen
+    .accesskey = H
+
+show-favorite-folders-label =
+    .label = Hoff Ffolderi
+    .accesskey = H
+
+show-smart-folders-label =
+    .label = Ffolderi Cyfun
+    .accesskey = y
+
+show-recent-folders-label =
+    .label = Ffolderi Diweddar
+    .accesskey = D
+
+folder-toolbar-toggle-folder-compact-view =
+    .label = Golwg Cryno
+    .accesskey = G
+
+## Menu
+
+redirect-msg-menuitem =
+    .label = Ailgyfeirio
+    .accesskey = A
+
+menu-file-save-as-file =
+    .label = Ffeil…
+    .accesskey = F
+
+## AppMenu
+
+appmenu-save-as-file =
+    .label = Ffeil…
+
+appmenu-settings =
+    .label = Gosodiadau
+
+appmenu-addons-and-themes =
+    .label = Ychwanegion a Themâu
+
+appmenu-help-enter-troubleshoot-mode =
+    .label = Datrys Problemau…
+
+appmenu-help-exit-troubleshoot-mode =
+    .label = Diffodd y Modd Datrys Problemau
+
+appmenu-help-more-troubleshooting-info =
+    .label = Rhagor o Wybodaeth i Ddatrys Problemau
+
+appmenu-redirect-msg =
+    .label = Ailgyfeirio
+
+## Context menu
+
+context-menu-redirect-msg =
+    .label = Ailgyfeirio
+
+mail-context-delete-messages =
+    .label =
+        { $count ->
+            [zero] Dileu'r Negeseuon Hyn
+            [one] Dileu'r Neges Hwn
+            [two] Dileu'r Negeseuon Hyn
+            [few] Dileu'r Negeseuon Hyn
+            [many] Dileu'r Negeseuon Hyn
+           *[other] Dileu'r Negeseuon Hyn
+        }
+
+context-menu-decrypt-to-folder =
+    .label = Copi Fel Wedi'i Ddatgryptio I.
+    .accesskey = D
+
+## Message header pane
+
+other-action-redirect-msg =
+    .label = Ailgyfeirio
+
+message-header-msg-flagged =
+    .title = Serennog
+    .aria-label = Serennog
+
+# Variables:
+# $address (String) - The email address of the recipient this picture belongs to.
+message-header-recipient-avatar =
+    .alt = Llun proffil { $address }.
+
+## Message header cutomize panel
+
+message-header-customize-panel-title = Gosodiadau Pennyn Neges
+
+message-header-customize-button-style =
+    .value = Arddull botwm
+    .accesskey = B
+
+message-header-button-style-default =
+    .label = Eiconau a thestun
+
+message-header-button-style-text =
+    .label = Testun
+
+message-header-button-style-icons =
+    .label = Eiconau
+
+message-header-show-sender-full-address =
+    .label = Dangos cyfeiriad llawn yr anfonwr bob tro
+    .accesskey = l
+
+message-header-show-sender-full-address-description = Bydd y cyfeiriad e-bost yn cael ei ddangos o dan yr enw dangos.
+
+message-header-show-recipient-avatar =
+    .label = Dangos llun proffil yr anfonwr
+    .accesskey = D
+
+message-header-hide-label-column =
+    .label = Cuddio colofn y labeli
+    .accesskey = u
+
+message-header-large-subject =
+    .label = Pwnc mawr
+    .accesskey = P
+
+message-header-all-headers =
+    .label = Dangos pob pennyn
+    .accesskey = D
+
+## Action Button Context Menu
+
+toolbar-context-menu-manage-extension =
+    .label = Rheoli Estyniad
+    .accesskey = E
+toolbar-context-menu-remove-extension =
+    .label = Tynnu Estyniad
+    .accesskey = T
+
+## Add-on removal warning
+
+# Variables:
+#  $name (String): The name of the addon that will be removed.
+addon-removal-title = Tynnu { $name }?
+addon-removal-confirmation-button = Tynnu
+addon-removal-confirmation-message = Tynnu { $name } yn ogystal â'i ffurfweddiad a'i ddata o { -brand-short-name }?
+
+caret-browsing-prompt-title = Pori Caret
+caret-browsing-prompt-text = Mae pwyso F7 yn cychwyn a diffodd Pori Caret. Mae'r nodwedd hon yn gosod cyrchwr symudol ar dudalennau gwe, gan ganiatáu i chi ddewis testun gyda'r bysellfwrdd. Hoffech chi gychwyn Pori Caret?
+caret-browsing-prompt-check-text = Peidio â gofyn eto.
+
+repair-text-encoding-button =
+    .label = Trwsio Amgodio Testun
+    .tooltiptext = Dyfalu'r amgodiad testun cywir o gynnwys y neges
+
+## no-reply handling
+
+no-reply-title = Nid yw Ateb yn cael ei Gefnogi
+no-reply-message = Nid yw'n ymddangos bod y cyfeiriad ateb ({ $email }) yn gyfeiriad wedi'i fonitro. Mae'n bosib na fydd unrhyw un yn darllen negeseuon i'r cyfeiriad hwn.
+no-reply-reply-anyway-button = Ateb Beth Bynnag
+
+## error messages
+
+decrypt-and-copy-failures = Nid oedd modd dadgryptio { $failures } o { $total } o negeseuon ac heb eu copïo.
+
+## Spaces toolbar
+
+spaces-toolbar-element =
+    .toolbarname = Bar Offer Mannau
+    .aria-label = Bar Offer Mannau
+    .aria-description = Bar offer fertigol ar gyfer symud rhwng mannau gwahanol. Defnyddiwch y bysellau saeth i ddefnyddio'r botymau sydd ar gael.
+
+spaces-toolbar-button-mail2 =
+    .title = E-bost
+
+spaces-toolbar-button-address-book2 =
+    .title = Llyfr Cyfeiriadau
+
+spaces-toolbar-button-calendar2 =
+    .title = Calendr
+
+spaces-toolbar-button-tasks2 =
+    .title = Tasgau
+
+spaces-toolbar-button-chat2 =
+    .title = Sgwrsio
+
+spaces-toolbar-button-overflow =
+    .title = Rhagor o fannau…
+
+spaces-toolbar-button-settings2 =
+    .title = Gosodiadau
+
+spaces-toolbar-button-hide =
+    .title = Cuddio Bar Offer Mannau
+
+spaces-toolbar-button-show =
+    .title = Dangos Bar Offer Mannau
+
+spaces-context-new-tab-item =
+    .label = Agor mewn tab newydd
+
+spaces-context-new-window-item =
+    .label = Agor mewn ffenestr newydd
+
+# Variables:
+# $tabName (String) - The name of the tab this item will switch to.
+spaces-context-switch-tab-item =
+    .label = Newid i { $tabName }
+
+settings-context-open-settings-item2 =
+    .label = Gosodiadau
+
+settings-context-open-account-settings-item2 =
+    .label = Gosodiadau Cyfrif
+
+settings-context-open-addons-item2 =
+    .label = Ychwanegion a Themâu
+
+## Spaces toolbar pinned tab menupopup
+
+spaces-toolbar-pinned-tab-button =
+    .tooltiptext = Dewislen Mannau
+
+spaces-pinned-button-menuitem-mail2 =
+    .label = { spaces-toolbar-button-mail2.title }
+
+spaces-pinned-button-menuitem-address-book2 =
+    .label = { spaces-toolbar-button-address-book2.title }
+
+spaces-pinned-button-menuitem-calendar2 =
+    .label = { spaces-toolbar-button-calendar2.title }
+
+spaces-pinned-button-menuitem-tasks2 =
+    .label = { spaces-toolbar-button-tasks2.title }
+
+spaces-pinned-button-menuitem-chat2 =
+    .label = { spaces-toolbar-button-chat2.title }
+
+spaces-pinned-button-menuitem-settings2 =
+    .label = { spaces-toolbar-button-settings2.title }
+
+spaces-pinned-button-menuitem-show =
+    .label = { spaces-toolbar-button-show.title }
+
+# Variables:
+# $count (Number) - Number of unread messages.
+chat-button-unread-messages = { $count }
+    .title =
+        { $count ->
+            [zero] Dim negeseuon heb eu darllen
+            [one] Un neges neb ei darllen
+            [two] { $count } heb eu darllen
+            [few] { $count } heb eu darllen
+            [many] { $count } heb eu darllen
+           *[other] { $count } heb eu darllen
+        }
+
+## Spaces toolbar customize panel
+
+menuitem-customize-label =
+    .label = Cyfaddasu…
+
+spaces-customize-panel-title = Gosodiadau Bar Offer Mannau
+
+spaces-customize-background-color = Lliw cefndir
+
+spaces-customize-icon-color = Lliw botwm
+
+# The background color used on the buttons of the spaces toolbar when they are
+# `current`, meaning the related space/tab is active and visible.
+spaces-customize-accent-background-color = Lliw cefndir botwm a ddewiswyd
+
+# The icon color used on the buttons of the spaces toolbar when they are
+# `current`, meaning the related space/tab is active and visible.
+spaces-customize-accent-text-color = Lliw botwm a ddewiswyd
+
+spaces-customize-button-restore = Adfer y Rhagosodiadau
+    .accesskey = R
+
+customize-panel-button-save = Gorffen
+    .accesskey = G
diff --git a/l10n-cy/mail/messenger/messengercompose/messengercompose.ftl b/l10n-cy/mail/messenger/messengercompose/messengercompose.ftl
new file mode 100644
index 0000000000..28336f46a5
--- /dev/null
+++ b/l10n-cy/mail/messenger/messengercompose/messengercompose.ftl
@@ -0,0 +1,490 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Send Format
+
+compose-send-format-menu =
+    .label = Fformat Anfon
+    .accesskey = F
+
+compose-send-auto-menu-item =
+    .label = Awtomatig
+    .accesskey = A
+
+compose-send-both-menu-item =
+    .label = HTML a Thestun Plaen
+    .accesskey = H
+
+compose-send-html-menu-item =
+    .label = Dim ond HTML
+    .accesskey = D
+
+compose-send-plain-menu-item =
+    .label = Dim ond Testun Plaen
+    .accesskey = T
+
+## Addressing widget
+
+#   $type (String) - the type of the addressing row
+remove-address-row-button =
+    .title = Tynnu'r maes { $type }
+
+#   $type (String) - the type of the addressing row
+#   $count (Number) - the number of address pills currently present in the addressing row
+address-input-type-aria-label =
+    { $count ->
+        [0] { $type }
+        [zero] { $type } gydag un cyfeiriad, defnyddiwch fysell y saeth chwith i ganolbwyntio arno.
+        [one] { $type } gyda { $count } cyfeiriad, defnyddiwch fysell y saeth chwith i ganolbwyntio arnyn nhw.
+        [two] { $type } gyda { $count } cyfeiriad, defnyddiwch fysell y saeth chwith i ganolbwyntio arnyn nhw.
+        [few] { $type } gyda { $count } cyfeiriad, defnyddiwch fysell y saeth chwith i ganolbwyntio arnyn nhw.
+        [many] { $type } gyda { $count } cyfeiriad, defnyddiwch fysell y saeth chwith i ganolbwyntio arnyn nhw.
+       *[other] { $type } gyda { $count } cyfeiriad, defnyddiwch fysell y saeth chwith i ganolbwyntio arnyn nhw.
+    }
+
+#   $email (String) - the email address
+#   $count (Number) - the number of address pills currently present in the addressing row
+pill-aria-label =
+    { $count ->
+        [zero] { $email }, 1 o { $count }: pwyswch Enter i olygu, Delete i ddileu
+        [one] { $email }: pwyswch Enter i olygu, Delete i ddileu
+        [two] { $email }, 1 o { $count }: pwyswch Enter i olygu, Delete i ddileu
+        [few] { $email }, 1 o { $count }: pwyswch Enter i olygu, Delete i ddileu
+        [many] { $email }, 1 o { $count }: pwyswch Enter i olygu, Delete i ddileu
+       *[other] { $email }, 1 o { $count }: pwyswch Enter i olygu, Delete i ddileu
+    }
+
+#   $email (String) - the email address
+pill-tooltip-invalid-address = Nid yw { $email } yn gyfeiriad e-bost dilys
+
+#   $email (String) - the email address
+pill-tooltip-not-in-address-book = Nid yw { $email } yn eich llyfr cyfeiriadau
+
+pill-action-edit =
+    .label = Golygu Cyfeiriad
+    .accesskey = G
+
+#   $type (String) - the type of the addressing row, e.g. Cc, Bcc, etc.
+pill-action-select-all-sibling-pills =
+    .label = Dewis Pob Cyfeiriad yn { $type }
+    .accesskey = D
+
+pill-action-select-all-pills =
+    .label = Dewis Pob Cyfeiriad
+    .accesskey = D
+
+pill-action-move-to =
+    .label = Symud i
+    .accesskey = S
+
+pill-action-move-cc =
+    .label = Symud i CC
+    .accesskey = C
+
+pill-action-move-bcc =
+    .label = Symud i Bcc
+    .accesskey = B
+
+pill-action-expand-list =
+    .label = Ehangu'r Rhestr
+    .accesskey = E
+
+## Attachment widget
+
+ctrl-cmd-shift-pretty-prefix =
+    { PLATFORM() ->
+        [macos] ⇧ ⌘{ " " }
+       *[other] Ctrl+Shift+
+    }
+
+trigger-attachment-picker-key = A
+toggle-attachment-pane-key = P
+
+menuitem-toggle-attachment-pane =
+    .label = Paen Atodiad
+    .accesskey = P
+    .acceltext = { ctrl-cmd-shift-pretty-prefix }{ toggle-attachment-pane-key }
+
+toolbar-button-add-attachment =
+    .label = Atodi
+    .tooltiptext = Atodi Atodiad ({ ctrl-cmd-shift-pretty-prefix }{ trigger-attachment-picker-key })
+
+add-attachment-notification-reminder2 =
+    .label = Ychwanegu Atodiad…
+    .accesskey = A
+    .tooltiptext = { toolbar-button-add-attachment.tooltiptext }
+
+menuitem-attach-files =
+    .label = Ffeil(iau)…
+    .accesskey = F
+    .acceltext = { ctrl-cmd-shift-pretty-prefix }{ trigger-attachment-picker-key }
+
+context-menuitem-attach-files =
+    .label = Atodi Ffeil(iau)…
+    .accesskey = F
+    .acceltext = { ctrl-cmd-shift-pretty-prefix }{ trigger-attachment-picker-key }
+
+# Note: Do not translate the term 'vCard'.
+context-menuitem-attach-vcard =
+    .label = Fy vCard
+    .accesskey = v
+
+context-menuitem-attach-openpgp-key =
+    .label = Fy Allwedd Gyhoeddus OpenPGP
+    .accesskey = O
+
+#   $count (Number) - the number of attachments in the attachment bucket
+attachment-bucket-count-value =
+    { $count ->
+        [1] { $count } Atodiad
+        [zero] { $count } Atodiadau
+        [one] { $count } Atodiad
+        [two] { $count } Atodiad
+        [few] { $count } Atodiad
+        [many] { $count } Atodiad
+       *[other] { $count } Atodiad
+    }
+
+attachment-area-show =
+    .title = Dangos y paen atodi ({ ctrl-cmd-shift-pretty-prefix }{ toggle-attachment-pane-key })
+
+attachment-area-hide =
+    .title = Cuddio'r paen atodi ({ ctrl-cmd-shift-pretty-prefix }{ toggle-attachment-pane-key })
+
+drop-file-label-attachment =
+    { $count ->
+        [zero] Ychwanegu fel Atodiadau
+        [one] Ychwanegu fel Atodiad
+        [two] Ychwanegu fel Atodiad
+        [few] Ychwanegu fel Atodiad
+        [many] Ychwanegu fel Atodiad
+       *[other] Ychwanegu fel Atodiad
+    }
+
+drop-file-label-inline =
+    { $count ->
+        [zero] Atodiadau ar-lein
+        [one] Atodiad ar-lein
+        [two] Atodiad ar-lein
+        [few] Atodiad ar-lein
+        [many] Atodiad ar-lein
+       *[other] Atodiad ar-lein
+    }
+
+## Reorder Attachment Panel
+
+move-attachment-first-panel-button =
+    .label = Symud yn Gyntaf
+move-attachment-left-panel-button =
+    .label = Symud i'r Chwith
+move-attachment-right-panel-button =
+    .label = Symud i'r Dde
+move-attachment-last-panel-button =
+    .label = Symud Olaf
+
+button-return-receipt =
+    .label = Derbynneb
+    .tooltiptext = Gofyn am dderbynneb dychwelyd i'r neges hon
+
+## Encryption
+
+encryption-menu =
+    .label = Diogelwch
+    .accesskey = D
+
+encryption-toggle =
+    .label = Amgryptio
+    .tooltiptext = Defnyddio amgryptiad ben-i-ben ar gyfer y neges yma
+
+encryption-options-openpgp =
+    .label = OpenPGP
+    .tooltiptext = Gweld neu newid gosodiadau amgryptio OpenPGP
+
+encryption-options-smime =
+    .label = S/MIME
+    .tooltiptext = Gweld neu newid goodiadau amgryptio S/MIME
+
+signing-toggle =
+    .label = Llofnodi
+    .tooltiptext = Defnyddio llofnodi digidol ar gyfer y neges hon
+
+menu-openpgp =
+    .label = OpenPGP
+    .accesskey = O
+
+menu-smime =
+    .label = S/MIME
+    .accesskey = S
+
+menu-encrypt =
+    .label = Amgryptio
+    .accesskey = A
+
+menu-encrypt-subject =
+    .label = Amgryptio Pwnc
+    .accesskey = p
+
+menu-sign =
+    .label = Llofnodi Digidol
+    .accesskey = L
+
+menu-manage-keys =
+    .label = Cynorthwy-ydd Allwedd
+    .accesskey = C
+
+menu-view-certificates =
+    .label = Gweld Tystysgrifau Derbynwyr
+    .accesskey = G
+
+menu-open-key-manager =
+    .label = Rheolwr Allwedd
+    .accesskey = R
+
+openpgp-key-issue-notification-one = Mae amgryptio pen-i-ben yn gofyn am ddatrys materion allweddi ar gyfer { $addr }
+openpgp-key-issue-notification-many = Mae amgryptio pen-i-ben yn gofyn am ddatrys materion allweddi ar gyfer { $count } derbynnydd.
+
+smime-cert-issue-notification-one = Mae amgryptio pen-i-ben yn gofyn am ddatrys materion tystysgrifau ar gyfer { $addr }.
+smime-cert-issue-notification-many = Mae amgryptio pen-i-ben yn gofyn am ddatrys materion tystysgrifau ar gyfer { $count } derbynnydd.
+
+key-notification-disable-encryption =
+    .label = Peidio ag Amgryptio
+    .accesskey = P
+    .tooltiptext = Analluogi amgryptio pen-i-ben
+
+key-notification-resolve =
+    .label = Datrys...
+    .accesskey = D
+    .tooltiptext = Agor Cynorthwydd Allweddi OpenPGP
+
+can-encrypt-smime-notification = Mae amgryptio S/MIME o ben-i-ben yn bosibl.
+
+can-encrypt-openpgp-notification = Mae amgryptio S/MIME o ben-i-ben yn bosibl.
+
+can-e2e-encrypt-button =
+    .label = Amgryptio
+    .accesskey = A
+
+## Addressing Area
+
+to-address-row-label =
+    .value = At
+
+#   $key (String) - the shortcut key for this field
+show-to-row-main-menuitem =
+    .label = I Faes
+    .accesskey = F
+    .acceltext = { ctrl-cmd-shift-pretty-prefix }{ $key }
+
+# No acceltext should be shown.
+# The label should match the show-to-row-button text.
+show-to-row-extra-menuitem =
+    .label = At
+    .accesskey = A
+
+#   $key (String) - the shortcut key for this field
+show-to-row-button = At
+    .title = Dangos i Faes ({ ctrl-cmd-shift-pretty-prefix }{ $key })
+
+
+cc-address-row-label =
+    .value = Cc
+
+#   $key (String) - the shortcut key for this field
+show-cc-row-main-menuitem =
+    .label = Maes Cc
+    .accesskey = C
+    .acceltext = { ctrl-cmd-shift-pretty-prefix }{ $key }
+
+# No acceltext should be shown.
+# The label should match the show-cc-row-button text.
+show-cc-row-extra-menuitem =
+    .label = Cc
+    .accesskey = C
+
+#   $key (String) - the shortcut key for this field
+show-cc-row-button = Cc
+    .title = Dangos Maes Cc ({ ctrl-cmd-shift-pretty-prefix }{ $key })
+
+
+bcc-address-row-label =
+    .value = Bcc
+
+#   $key (String) - the shortcut key for this field
+show-bcc-row-main-menuitem =
+    .label = Maes Bcc
+    .accesskey = B
+    .acceltext = { ctrl-cmd-shift-pretty-prefix }{ $key }
+
+# No acceltext should be shown.
+# The label should match the show-bcc-row-button text.
+show-bcc-row-extra-menuitem =
+    .label = Bcc
+    .accesskey = B
+
+#   $key (String) - the shortcut key for this field
+show-bcc-row-button = Bcc
+    .title = Dangos Maes Bcc ({ ctrl-cmd-shift-pretty-prefix }{ $key })
+
+extra-address-rows-menu-button =
+    .title = Meysydd cyfeiriadau eraill i'w dangos
+
+#   $count (Number) - the count of addresses in the "To" and "Cc" fields.
+many-public-recipients-notice =
+    { $count ->
+        [zero] Nid oes gan eich neges unrhyw dderbynydd.
+        [one] osgoi datgelu derbynwyr trwy ddefnyddio Bcc yn lle.
+        [two] Bydd y  { $count } derbyniwr yn At a Cc yn gweld cyfeiriad ei gilydd. Gallwch osgoi datgelu derbynwyr trwy ddefnyddio Bcc yn lle.
+        [few] Bydd y  { $count } derbyniwr yn At a Cc yn gweld cyfeiriad ei gilydd. Gallwch osgoi datgelu derbynwyr trwy ddefnyddio Bcc yn lle.
+        [many] Bydd y  { $count } derbyniwr yn At a Cc yn gweld cyfeiriad ei gilydd. Gallwch osgoi datgelu derbynwyr trwy ddefnyddio Bcc yn lle.
+       *[other] Bydd y  { $count } derbyniwr yn At a Cc yn gweld cyfeiriad ei gilydd. Gallwch osgoi datgelu derbynwyr trwy ddefnyddio Bcc yn lle.
+    }
+many-public-recipients-bcc =
+    .label = Defnyddio Bcc yn lle hynny
+    .accesskey = D
+
+many-public-recipients-ignore =
+    .label = Cadw Derbynwyr yn Gyhoeddus
+    .accesskey = G
+
+many-public-recipients-prompt-title = Gormod o Dderbynwyr Cyhoeddus
+
+#   $count (Number) - the count of addresses in the public recipients fields.
+many-public-recipients-prompt-msg =
+    { $count ->
+        [zero] Nid oes gan eich neges unrhyw dderbyniwr.
+        [one] Mae gan eich neges dderbynwyr cyhoeddus. Gall hyn fod yn bryder preifatrwydd. Gallwch osgoi datgelu derbynwyr trwy symud derbynwyr o At /Cc i Bcc yn lle.
+        [two] Mae gan eich neges { $count } derbynwyr cyhoeddus, a fydd yn gallu gweld cyfeiriadau ei gilydd. Gall hyn fod yn bryder preifatrwydd. Gallwch osgoi datgelu derbynwyr trwy symud derbynwyr o At /Cc i Bcc yn lle.
+        [few] Mae gan eich neges { $count } derbynwyr cyhoeddus, a fydd yn gallu gweld cyfeiriadau ei gilydd. Gall hyn fod yn bryder preifatrwydd. Gallwch osgoi datgelu derbynwyr trwy symud derbynwyr o At /Cc i Bcc yn lle.
+        [many] Mae gan eich neges { $count } derbynwyr cyhoeddus, a fydd yn gallu gweld cyfeiriadau ei gilydd. Gall hyn fod yn bryder preifatrwydd. Gallwch osgoi datgelu derbynwyr trwy symud derbynwyr o At /Cc i Bcc yn lle.
+       *[other] Mae gan eich neges { $count } derbynwyr cyhoeddus, a fydd yn gallu gweld cyfeiriadau ei gilydd. Gall hyn fod yn bryder preifatrwydd. Gallwch osgoi datgelu derbynwyr trwy symud derbynwyr o At /Cc i Bcc yn lle.
+    }
+
+many-public-recipients-prompt-cancel = Diddymu Anfon
+many-public-recipients-prompt-send = Anfonwch Beth Bynnag
+
+## Notifications
+
+# Variables:
+# $identity (string) - The name of the used identity, most likely an email address.
+compose-missing-identity-warning = Methu canfod hunaniaeth unigryw sy'n cyd-fynd a'r cyfeiriad Oddi wrth. Bydd y neges yn cael ei hanfon gan ddefnyddio'r maes Oddi wrth cyfredol a'r gosodiadau o hunaniaeth { $identity }.
+
+encrypted-bcc-warning = Wrth anfon neges wedi'i hamgryptio, nid yw'r derbynwyr yn Bcc wedi'u cuddio'n llawn. Efallai y bydd pob derbynnydd yn gallu eu hadnabod.
+
+encrypted-bcc-ignore-button = Wedi Deall
+
+## Editing
+
+
+# Tools
+
+compose-tool-button-remove-text-styling =
+    .tooltiptext = Tynnu Steilio Testun
+
+## Filelink
+
+# A text used in a tooltip of Filelink attachments, whose account has been
+# removed or is unknown.
+cloud-file-unknown-account-tooltip = Wedi'i lwytho i gyfrif Filelink anhysbys.
+
+# Placeholder file
+
+# Title for the html placeholder file.
+# $filename - name of the file
+cloud-file-placeholder-title = { $filename } - Atodiad Filelink
+
+# A text describing that the file was attached as a Filelink and can be downloaded
+# from the link shown below.
+# $filename - name of the file
+cloud-file-placeholder-intro = Atodwyd y ffeil { $filename } fel Filelink. Mae modd ei lwytho i lawr o'r ddolen isod.
+
+# Template
+
+# A line of text describing how many uploaded files have been appended to this
+# message. Emphasis should be on sharing as opposed to attaching. This item is
+# used as a header to a list, hence the colon.
+cloud-file-count-header =
+    { $count ->
+        [zero] Rwyf wedi cysylltu { $count } ffeil i'r e-bost hwn:
+        [one] Rwyf wedi cysylltu { $count } ffeil i'r e-bost hwn:
+        [two] Rwyf wedi cysylltu { $count } ffeil i'r e-bost hwn:
+        [few] Rwyf wedi cysylltu { $count } ffeil i'r e-bost hwn:
+        [many] Rwyf wedi cysylltu { $count } ffeil i'r e-bost hwn:
+       *[other] Rwyf wedi cysylltu { $count } ffeil i'r e-bost hwn:
+    }
+
+# A text used in a footer, instructing the reader where to find additional
+# information about the used service provider.
+# $link (string) - html a-tag for a link pointing to the web page of the provider
+cloud-file-service-provider-footer-single = Dysgu rhagor am { $link }.
+
+# A text used in a footer, instructing the reader where to find additional
+# information about the used service providers. Links for the used providers are
+# split into a comma separated list of the first n-1 providers and a single entry
+# at the end.
+# $firstLinks (string) - comma separated list of html a-tags pointing to web pages
+#                        of the first n-1 used providers
+# $lastLink (string) - html a-tag pointing the web page of the n-th used provider
+cloud-file-service-provider-footer-multiple = Dysgu rhagor am { $firstLinks } a { $lastLink }.
+
+# Tooltip for an icon, indicating that the link is protected by a password.
+cloud-file-tooltip-password-protected-link = Dolen wedi'i diogelu gan gyfrinair
+
+# Used in a list of stats about a specific file
+# Service - the used service provider to host the file (Filelink Service: BOX.com)
+# Size - the size of the file (Size: 4.2 MB)
+# Link - the link to the file (Link: https://some.provider.com)
+# Expiry Date - stating the date the link will expire (Expiry Date: 12.12.2022)
+# Download Limit - stating the maximum allowed downloads, before the link becomes invalid
+#                  (Download Limit: 6)
+cloud-file-template-service-name = Gwasanaeth Filelink:
+cloud-file-template-size = Maint:
+cloud-file-template-link = Dolen:
+cloud-file-template-password-protected-link = Dolen wedi'i Diogelu gan Gyfrinair
+cloud-file-template-expiry-date = Dyddiad Dod i Ben:
+cloud-file-template-download-limit = Terfyn Llwytho i Lawr:
+
+# Messages
+
+# $provider (string) - name of the online storage service that reported the error
+cloud-file-connection-error-title = Gwall Cysylltiad
+cloud-file-connection-error = Mae { -brand-short-name } all-lein. Methu cysylltu â { $provider }.
+
+# $provider (string) - name of the online storage service that reported the error
+# $filename (string) - name of the file that was uploaded and caused the error
+cloud-file-upload-error-with-custom-message-title = Methodd Llwytho { $filename } i { $provider }
+
+# $provider (string) - name of the online storage service that reported the error
+# $filename (string) - name of the file that was renamed and caused the error
+cloud-file-rename-error-title = Gwall Ail-enwi
+cloud-file-rename-error = Bu anhawster wrth ailenwi { $filename } ar { $provider }.
+
+# $provider (string) - name of the online storage service that reported the error
+# $filename (string) - name of the file that was renamed and caused the error
+cloud-file-rename-error-with-custom-message-title = Methodd ail-enwi { $filename } ar { $provider }
+
+# $provider (string) - name of the online storage service that reported the error
+cloud-file-rename-not-supported = Nid yw { $provider } yn cefnogi ailenwi ffeiliau sydd eisoes wedi'u llwytho i fyny.
+
+# $filename (string) - name of the file that was renamed and caused the error
+cloud-file-attachment-error-title = Gwall Atodi Filelink
+cloud-file-attachment-error = Wedi methu diweddaru'r atodiad Filelink { $filename }, oherwydd bod ei ffeil leol wedi'i symud neu ei dileu.
+
+# $filename (string) - name of the file that was renamed and caused the error
+cloud-file-account-error-title = Gwall Cyfrif Filelink
+cloud-file-account-error = Wedi methu diweddaru'r atodiad Filelink { $filename }, oherwydd bod ei ffeil leol wedi'i symud neu ei dileu.
+
+## Link Preview
+
+link-preview-title = Rhagolwg Dolen
+link-preview-description = Gall { -brand-short-name } ychwanegu rhagolwg wedi'i fewnblannu wrth ludo dolenni.
+link-preview-autoadd = Ychwanegu ragolygon dolenni'n awtomatig pan fo modd
+link-preview-replace-now = Ychwanegu Rhagolwg Dolen ar gyfer y ddolen hon?
+link-preview-yes-replace = Iawn
+
+## Dictionary selection popup
+
+spell-add-dictionaries =
+    .label = Ychwanegu Geiriaduron…
+    .accesskey = Y
diff --git a/l10n-cy/mail/messenger/migration.ftl b/l10n-cy/mail/messenger/migration.ftl
new file mode 100644
index 0000000000..302a661820
--- /dev/null
+++ b/l10n-cy/mail/messenger/migration.ftl
@@ -0,0 +1,15 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, you can obtain one at http://mozilla.org/MPL/2.0/.
+
+migration-progress-header = Yn cael { -brand-short-name } yn barod…
+
+## Migration tasks
+
+
+# These strings are displayed to the user if a migration is taking a long time.
+# They should be short (no more than a handful of words) and in the present tense.
+
+migration-task-test-fast = Yn profi newid cyflym
+migration-task-test-slow = Yn profi newid araf
+migration-task-test-progress = Yn profi'r bar cynnydd
diff --git a/l10n-cy/mail/messenger/openpgp/backupKeyPassword.ftl b/l10n-cy/mail/messenger/openpgp/backupKeyPassword.ftl
new file mode 100644
index 0000000000..531931573a
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/backupKeyPassword.ftl
@@ -0,0 +1,20 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+set-password-window =
+    .title = Dewiswch gyfrinair i wneud copi wrth gefn o'ch Allwedd OpenPGP
+
+set-password-legend = Dewiswch Gyfrinair
+
+set-password-message = Bydd y cyfrinair wrth gefn yma'n diogelu'r allwedd gyfrinachol OpenPGP wrth gefn rydych ar fin ei chreu.  Rhaid gosod y cyfrinair i barhau gyda'r ffeil wrth gefn.
+
+set-password-backup-pw =
+    .value = Cyfrinair wrth gefn Allwedd Cyfrinachol:
+
+set-password-repeat-backup-pw =
+    .value = Cyfrinair wrth gefn Allwedd Cyfrinachol (eto):
+
+set-password-reminder = <b>Pwysig!</b> Os byddwch yn anghofio eich cyfrinair diogelwch wrth gefn, ni fydd modd i chi adfer y ffeil wrth gefn yma eto.  Cofnodwch hwn mewn man diogel.
+
+password-quality-meter = Mesurydd ansawdd cyfrinair
diff --git a/l10n-cy/mail/messenger/openpgp/changeExpiryDlg.ftl b/l10n-cy/mail/messenger/openpgp/changeExpiryDlg.ftl
new file mode 100644
index 0000000000..e2b941038a
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/changeExpiryDlg.ftl
@@ -0,0 +1,22 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+openpgp-change-key-expiry-title =
+    .title = Newid Dod i Ben yr Allwedd
+
+info-will-expire = Mae'r allwedd hon wedi'i ffurfweddu i ddod i ben ar { $date }
+info-already-expired = Mae'r allwedd hon eisoes wedi dod i ben.
+info-does-not-expire = Mae'r allwedd hon wedi'i ffurfweddu i beidio byth â dod i ben.
+
+info-explanation-1 = <b>Ar ôl i allwedd ddod i ben</b>, nid yw bellach yn bosibl ei defnyddio ar gyfer amgryptio neu arwyddo digidol.
+
+info-explanation-2 = I ddefnyddio'r allwedd hon am gyfnod hirach, newidiwch ei dyddiad dod i ben, ac yna rhannwch yr allwedd gyhoeddus gyda'ch partneriaid sgwrsio eto.
+
+expire-dont-change =
+    .label = Peidiwch â newid y dyddiad dod i ben
+expire-never-label =
+    .label = Ni fydd yr allwedd byth yn dod i ben
+expire-in-label =
+    .label = Bydd yr allwedd yn dod i ben ar:
+expire-in-months = Mis
diff --git a/l10n-cy/mail/messenger/openpgp/composeKeyStatus.ftl b/l10n-cy/mail/messenger/openpgp/composeKeyStatus.ftl
new file mode 100644
index 0000000000..da66fc7197
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/composeKeyStatus.ftl
@@ -0,0 +1,28 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+openpgp-compose-key-status-intro-need-keys = I anfon neges wedi'i hamgryptio o ben-i-ben, rhaid i chi gael a derbyn allwedd gyhoeddus ar gyfer pob derbynnydd.
+openpgp-compose-key-status-keys-heading = Argaeledd allweddi OpenPGP:
+openpgp-compose-key-status-title =
+    .title = Diogelwch Negeseuon OpenPGP
+openpgp-compose-key-status-recipient =
+    .label = Derbynnydd
+openpgp-compose-key-status-status =
+    .label = Statws
+openpgp-compose-key-status-open-details = Rheoli allweddi ar gyfer derbynnydd dewisol...
+openpgp-recip-good = Iawn
+openpgp-recip-missing = dim allwedd ar gael
+openpgp-recip-none-accepted = dim allwedd wedi'i derbyn
+openpgp-compose-general-info-alias = Mae { -brand-short-name } fel arfer yn disgwyl bod allwedd gyhoeddus y derbynnydd yn cynnwys ID defnyddiwr gyda chyfeiriad e-bost sy'n cyfateb. Mae modd diystyru hyn trwy ddefnyddio rheolau alias derbynnydd OpenPGP.
+openpgp-compose-general-info-alias-learn-more = Dysgu rhagor
+openpgp-compose-alias-status-direct =
+    { $count ->
+        [zero] heb ei fapio i allweddi alias
+        [one] wedi'i fapio i { $count } allwedd alias
+        [two] wedi'i fapio i { $count } allwedd alias
+        [few] wedi'i fapio i { $count } allwedd alias
+        [many] wedi'i fapio i { $count }allwedd alias
+       *[other] wedi'i fapio i { $count } allwedd alias
+    }
+openpgp-compose-alias-status-error = allwedd alias nad oes modd ei ddefnyddio/ddim ar gael
diff --git a/l10n-cy/mail/messenger/openpgp/keyAssistant.ftl b/l10n-cy/mail/messenger/openpgp/keyAssistant.ftl
new file mode 100644
index 0000000000..5b8aca4779
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/keyAssistant.ftl
@@ -0,0 +1,177 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+openpgp-key-assistant-title = Cynorthwy-ydd Allwedd OpenPGP
+
+openpgp-key-assistant-rogue-warning = Ceisiwch osgoi derbyn allwedd ffug. Er mwyn sicrhau eich bod wedi cael yr allwedd gywir dylech ei wirio. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+
+## Encryption status
+
+openpgp-key-assistant-recipients-issue-header = Methu Amgryptio
+
+# Variables:
+# $count (Number) - The number of recipients that need attention.
+openpgp-key-assistant-recipients-issue-description =
+    { $count ->
+        [zero] I amgryptio, rhaid i chi gael a derbyn allweddi defnyddiadwy ar gyfer { $count } derbynwyr. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+        [one] I amgryptio, rhaid i chi gael a derbyn allwedd ddefnyddiadwy ar gyfer un derbynydd. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+        [two] I amgryptio, rhaid i chi gael a derbyn allweddi defnyddiadwy ar gyfer { $count } derbynwyr. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+        [few] I amgryptio, rhaid i chi gael a derbyn allweddi defnyddiadwy ar gyfer { $count } derbynwyr. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+        [many] I amgryptio, rhaid i chi gael a derbyn allweddi defnyddiadwy ar gyfer { $count } derbynwyr. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+       *[other] I amgryptio, rhaid i chi gael a derbyn allweddi defnyddiadwy ar gyfer { $count } derbynwyr. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+    }
+
+openpgp-key-assistant-info-alias = Mae { -brand-short-name } fel arfer yn disgwyl bod allwedd gyhoeddus y derbynnydd yn cynnwys ID defnyddiwr gyda chyfeiriad e-bost sy'n cyfateb. Mae modd diystyru hyn trwy ddefnyddio rheolau alias derbynnydd OpenPGP. <a data-l10n-name="openpgp-link">Dysgu rhagor…</a>
+
+# Variables:
+# $count (Number) - The number of recipients that need attention.
+openpgp-key-assistant-recipients-description =
+    { $count ->
+        [zero] Mae gennych eisoes allweddi defnyddiadwy a derbyniol ar gyfer { $count } o dderbynwyr .
+        [one] Mae gennych eisoes allweddi defnyddiadwy a derbyniol ar gyfer un derbynydd.
+        [two] Mae gennych eisoes allweddi defnyddiadwy a derbyniol ar gyfer { $count } dderbynydd.
+        [few] Mae gennych eisoes allweddi defnyddiadwy a derbyniol ar gyfer { $count } derbynydd.
+        [many] Mae gennych eisoes allweddi defnyddiadwy a derbyniol ar gyfer { $count } derbynydd..
+       *[other] Mae gennych eisoes allweddi defnyddiadwy a derbyniol ar gyfer { $count } derbynydd..
+    }
+
+openpgp-key-assistant-recipients-description-no-issues = Mae modd amgryptio'r neges hon. Mae gennych allweddi defnyddiadwy a derbyniol ar gyfer pob derbynnydd.
+
+## Resolve section
+
+# Variables:
+# $recipient (String) - The email address of the recipient needing resolution.
+# $numKeys (Number) - The number of keys.
+openpgp-key-assistant-resolve-title =
+    { $numKeys ->
+        [zero] Mae { -brand-short-name } wedi dod o hyd i'r allweddi canlynol ar gyfer { $recipient } .
+        [one] Mae { -brand-short-name } wedi dod o hyd i'r allwedd ganlynol ar gyfer { $recipient } .
+        [two] Mae { -brand-short-name } wedi dod o hyd i'r allweddi canlynol ar gyfer { $recipient } .
+        [few] Mae { -brand-short-name } wedi dod o hyd i'r allweddi canlynol ar gyfer { $recipient } .
+        [many] Mae { -brand-short-name } wedi dod o hyd i'r allweddi canlynol ar gyfer { $recipient } .
+       *[other] Mae { -brand-short-name } wedi dod o hyd i'r allweddi canlynol ar gyfer { $recipient } .
+    }
+
+openpgp-key-assistant-valid-description = Dewiswch yr allwedd rydych am ei dderbyn
+
+# Variables:
+# $numKeys (Number) - The number of available keys.
+openpgp-key-assistant-invalid-title =
+    { $numKeys ->
+        [zero] Nid oes modd defnyddio'r allweddi canlynol, oni bai eich bod wedi cael diweddariad.
+        [one] Nid oes modd defnyddio'r allwedd ganlynol, oni bai eich bod wedi cael diweddariad.
+        [two] Nid oes modd defnyddio'r allweddi canlynol, oni bai eich bod wedi cael diweddariad.
+        [few] Nid oes modd defnyddio'r allweddi canlynol, oni bai eich bod wedi cael diweddariad.
+        [many] Nid oes modd defnyddio'r allweddi canlynol, oni bai eich bod wedi cael diweddariad.
+       *[other] Nid oes modd defnyddio'r allweddi canlynol, oni bai eich bod wedi cael diweddariad.
+    }
+
+openpgp-key-assistant-no-key-available = Dim allwedd ar gael.
+
+openpgp-key-assistant-multiple-keys = Mae nifer o allweddi ar gael.
+
+# Variables:
+# $count (Number) - The number of unaccepted keys.
+openpgp-key-assistant-key-unaccepted =
+    { $count ->
+        [zero] Mae nifer o allweddi ar gael, ond nid oes yr un ohonynt wedi'u derbyn eto.
+        [one] Mae allwedd ar gael, ond nid yw wedi'i dderbyn eto.
+        [two] Mae nifer o allweddi ar gael, ond nid oes yr un ohonynt wedi'u derbyn eto.
+        [few] Mae nifer o allweddi ar gael, ond nid oes yr un ohonynt wedi'u derbyn eto.
+        [many] Mae nifer o allweddi ar gael, ond nid oes yr un ohonynt wedi'u derbyn eto.
+       *[other] Mae nifer o allweddi ar gael, ond nid oes yr un ohonynt wedi'u derbyn eto.
+    }
+
+# Variables:
+# $date (String) - The expiration date of the key.
+openpgp-key-assistant-key-accepted-expired = Mae allwedd sydd wedi'i dderbyn wedi dod i ben ar { $date }.
+
+openpgp-key-assistant-keys-accepted-expired = Mae nifer o allweddi â dderbyniwyd wedi dod i ben.
+
+# Variables:
+# $date (String) - The expiration date of the key.
+openpgp-key-assistant-this-key-accepted-expired = Cafodd yr allwedd hon ei derbyn cynt ond daeth i ben ar { $date }.
+
+# Variables:
+# $date (String) - The expiration date of the key.
+openpgp-key-assistant-key-unaccepted-expired-one = Daeth yr allwedd i ben ar { $date }.
+openpgp-key-assistant-key-unaccepted-expired-many = Mae nifer o allweddi wedi dod i ben.
+
+openpgp-key-assistant-key-fingerprint = Bysbrint
+
+openpgp-key-assistant-key-source =
+    { $count ->
+        [zero] Ffynonellau
+        [one] Ffynhonnell
+        [two] Ffynhonnell
+        [few] Ffynhonnell
+        [many] Ffynhonnell
+       *[other] Ffynhonnell
+    }
+
+openpgp-key-assistant-key-collected-attachment = atodiad e-bost
+openpgp-key-assistant-key-collected-autocrypt = Pennyn awtoamgrypt
+openpgp-key-assistant-key-collected-keyserver = gweinydd allweddi
+openpgp-key-assistant-key-collected-wkd = Cyfeiriadur Allweddi Gwe
+
+openpgp-key-assistant-keys-has-collected =
+    { $count ->
+        [zero] Cafodd nifer o allweddi eu canfod, ond nid oes yr un ohonyn nhw wedi'u derbyn eto.
+        [one] Cafodd un allwedd ei ganfod, ond nid nid yw wedi'i dderbyn eto.
+        [two] Cafodd nifer o allweddi eu canfod, ond nid oes yr un ohonyn nhw wedi'u derbyn eto.
+        [few] Cafodd nifer o allweddi eu canfod, ond nid oes yr un ohonyn nhw wedi'u derbyn eto.
+        [many] Cafodd nifer o allweddi eu canfod, ond nid oes yr un ohonyn nhw wedi'u derbyn eto.
+       *[other] Cafodd nifer o allweddi eu canfod, ond nid oes yr un ohonyn nhw wedi'u derbyn eto.
+    }
+
+openpgp-key-assistant-key-rejected = Cafodd yr allwedd hon ei gwrthod gynt.
+openpgp-key-assistant-key-accepted-other = Cafodd yr  allwedd hon ei derbyn gynt ar gyfer cyfeiriad e-bost gwahanol.
+
+# Variables:
+# $recipient (String) - The email address of the recipient needing resolution.
+openpgp-key-assistant-resolve-discover-info = Darganfod allweddi ychwanegol neu rhai wedi'u diweddaru ar gyfer { $recipient } ar-lein, neu eu mewnforio o ffeil.
+
+## Discovery section
+
+openpgp-key-assistant-discover-title = Wrthi'n darganfod ar-lein.
+
+# Variables:
+# $recipient (String) - The email address which we're discovering keys.
+openpgp-key-assistant-discover-keys = Wrthi'n darganfod allweddi ar gyfer { $recipient }…
+
+# Variables:
+# $recipient (String) - The email address which we're discovering keys.
+openpgp-key-assistant-expired-key-update =
+    Cafwyd hyd i ddiweddariad ar gyfer un o'r allweddi a dderbyniwyd gynt ar gyfer { $recipient }.
+    Mae modd ei ddefnyddio nawr gan nad yw bellach wedi dod i ben.
+
+## Dialog buttons
+
+openpgp-key-assistant-discover-online-button = Darganfod Allweddi Cyhoeddus Ar-lein…
+
+openpgp-key-assistant-import-keys-button = Mewnforio Allweddi Cyhoeddus o'r Ffeil…
+
+openpgp-key-assistant-issue-resolve-button = Datrys...
+
+openpgp-key-assistant-view-key-button = Gweld Allwedd…
+
+openpgp-key-assistant-recipients-show-button = Dangos
+
+openpgp-key-assistant-recipients-hide-button = Cuddio
+
+openpgp-key-assistant-cancel-button = Diddymu
+
+openpgp-key-assistant-back-button = Nôl
+
+openpgp-key-assistant-accept-button = Derbyn
+
+openpgp-key-assistant-close-button = Cau
+
+openpgp-key-assistant-disable-button = Analluogi Amgryptio
+
+openpgp-key-assistant-confirm-button = Anfon Wedi'i Amgryptio
+
+# Variables:
+# $date (String) - The key creation date.
+openpgp-key-assistant-key-created = crëwyd ar { $date }
diff --git a/l10n-cy/mail/messenger/openpgp/keyWizard.ftl b/l10n-cy/mail/messenger/openpgp/keyWizard.ftl
new file mode 100644
index 0000000000..4201301a97
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/keyWizard.ftl
@@ -0,0 +1,196 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#   $identity (String) - the email address of the currently selected identity
+key-wizard-dialog-window =
+    .title = Ychwanegu Allwedd OpenPGP Personol ar gyfer { $identity }
+
+key-wizard-button =
+    .buttonlabelaccept = Parhau
+    .buttonlabelhelp = Nôl
+
+key-wizard-dialog =
+    .buttonlabelaccept = Parhau
+    .buttonlabelextra1 = Mynd nôl
+
+key-wizard-warning = <b>Os oes gennych allwedd bersonol bresennol</b> ar gyfer y cyfeiriad e-bost hwn, dylech ei fewnforio. Fel arall ni fydd gennych fynediad i'ch archifau o e-byst wedi'u hamgryptio, nac yn gallu darllen e-byst wedi'u hamgryptio rydych yn eu derbyn gan bobl sy'n dal i ddefnyddio'ch allwedd bresennol.
+
+key-wizard-learn-more = Dysgu rhagor
+
+radio-create-key =
+    .label = Creu Allwedd OpenPGP newydd
+    .accesskey = C
+
+radio-import-key =
+    .label = Mewnforio Allwedd OpenPGP cyfredol
+    .accesskey = M
+
+radio-gnupg-key =
+    .label = Defnyddio'ch allwedd allanol trwy GnuPG (e.e. o gerdyn clyfar)
+    .accesskey = D
+
+## Generate key section
+
+openpgp-generate-key-title = Cynhyrchu Allwedd OpenPGP
+
+openpgp-generate-key-info = <b>Gall cynhyrchu allweddol gymryd rhai munudau i'w gwblhau.</b> Peidiwch â gadael y rhaglen tra bo'r allwedd yn cael ei gynhyrchu. Bydd pori neu berfformio gweithrediadau disg-ddwys yn ystod cynhyrchu'r allwedd yn ailgyflenwi'r 'gronfa ar hap' ac yn cyflymu'r broses. Cewch eich rhybuddio pan fydd cynhyrchu'r allweddol wedi'i gwblhau.
+
+openpgp-keygen-expiry-title = Allwedd yn dod i ben
+
+openpgp-keygen-expiry-description = Diffiniwch amser dod i ben eich allwedd sydd newydd ei chynhyrchu. Yn ddiweddarach, gallwch reoli'r dyddiad i'w ymestyn os oes angen.
+
+radio-keygen-expiry =
+    .label = Allwedd yn dod i ben ar
+    .accesskey = l
+
+radio-keygen-no-expiry =
+    .label = Nid yw'r allwedd yn dod i ben
+    .accesskey = N
+
+openpgp-keygen-days-label =
+    .label = diwrnod
+openpgp-keygen-months-label =
+    .label = mis
+openpgp-keygen-years-label =
+    .label = blwyddyn
+
+openpgp-keygen-advanced-title = Gosodiadau uwch
+
+openpgp-keygen-advanced-description = Rheoli gosodiadau uwch eich Allwedd OpenPGP.
+
+openpgp-keygen-keytype =
+    .value = Math o allwedd:
+    .accesskey = M
+
+openpgp-keygen-keysize =
+    .value = Maint yr allwedd:
+    .accesskey = a
+
+openpgp-keygen-type-rsa =
+    .label = RSA
+
+openpgp-keygen-type-ecc =
+    .label = ECC (Cromlin Elliptig)
+
+openpgp-keygen-button = Cynhyrchu allwedd
+
+openpgp-keygen-progress-title = Cynhyrchu eich Allwedd OpenPGP newydd ...
+
+openpgp-keygen-import-progress-title = Mewnforio eich Allweddi OpenPGP...
+
+openpgp-import-success = Allweddi OpenPGP wedi'u mewnforio'n llwyddiannus!
+
+openpgp-import-success-title = Cwblhewch y broses fewnforio
+
+openpgp-import-success-description = I ddechrau defnyddio'ch allwedd OpenPGP wedi'i fewnforio ar gyfer amgryptio e-bost, caewch y dialog hwn ac ewch i'ch Gosodiadau Cyfrif i'w ddewis.
+
+openpgp-keygen-confirm =
+    .label = Cadarnhau
+
+openpgp-keygen-dismiss =
+    .label = Diddymu
+
+openpgp-keygen-cancel =
+    .label = Diddymu'r broses ...
+
+openpgp-keygen-import-complete =
+    .label = Cau
+    .accesskey = C
+
+openpgp-keygen-missing-username = Nid oes enw wedi'i nodi ar gyfer y cyfrif cyfredol. Rhowch werth yn y maes "Eich enw" yng ngosodiadau'r cyfrif.
+openpgp-keygen-long-expiry = Nid oes modd i chi greu allwedd sy'n dod i ben mewn mwy na 100 mlynedd.
+openpgp-keygen-short-expiry = Rhaid i'ch allwedd fod yn ddilys am o leiaf un diwrnod.
+
+openpgp-keygen-ongoing = Eisoes wrthi'n cynhyrchu allwedd!
+
+openpgp-keygen-error-core = Methu cychwyn Gwasanaeth Craidd OpenPGP
+
+openpgp-keygen-error-failed = Yn annisgwyl, methwyd cynhyrchu allwedd OpenPGP
+
+#   $identity (String) - the newly generate OpenPGP Key
+openpgp-keygen-error-revocation = Crëwyd Allwedd OpenPGP yn llwyddiannus, ond methodd â chael dirymiad ar gyfer allwedd { $key }
+
+openpgp-keygen-abort-title = Atal cynhyrchu allwedd?
+openpgp-keygen-abort = Mae cynhyrchu allwedd OpenPGP ar y gweill ar hyn o bryd, a ydych chi'n siŵr eich bod am ei ddiddymu?
+
+#   $identity (String) - the name and email address of the currently selected identity
+openpgp-key-confirm = Cynhyrchu allwedd gyhoeddus a chyfrinachol ar gyfer { $identity }?
+
+## Import Key section
+
+openpgp-import-key-title = Mewnforio Allwedd OpenPGP personol sy'n bodoli eisoes
+
+openpgp-import-key-legend = Dewis ffeil a gadwyd wrth gefn.
+
+openpgp-import-key-description = Gallwch fewnforio allweddi personol a gafodd eu creu gyda meddalwedd OpenPGP arall.
+
+openpgp-import-key-info = Gall meddalwedd arall ddisgrifio allwedd bersonol gan ddefnyddio termau amgen fel eich allwedd eich hun, allwedd gyfrinachol, allwedd breifat neu bar o allweddi.
+
+#   $count (Number) - the number of keys found in the selected files
+openpgp-import-key-list-amount-2 =
+    { $count ->
+        [zero] Daeth { -brand-short-name } o hyd i { $count } allweddi y mae modd eu mewnforio.
+        [one] Daeth { -brand-short-name } o hyd i un allwedd y mae modd ei fewnforio.
+        [two] Daeth { -brand-short-name } o hyd i { $count } allweddi y mae modd eu mewnforio.
+        [few] Daeth { -brand-short-name } o hyd i { $count } allweddi y mae modd eu mewnforio.
+        [many] Daeth { -brand-short-name } o hyd i { $count } allweddi y mae modd eu mewnforio.
+       *[other] Daeth { -brand-short-name } o hyd i { $count } allweddi y mae modd eu mewnforio.
+    }
+
+openpgp-import-key-list-description = Cadarnhewch pa allweddi y mae modd eu trin fel eich allweddi personol. Dim ond allweddi y gwnaethoch chi eu creu eich hun ac sy'n dangos eich hunaniaeth eich hun y dylid eu defnyddio fel allweddi personol. Gallwch newid yr dewis hwn yn nes ymlaen yn y dialog Priodweddau Allweddi.
+
+openpgp-import-key-list-caption = Bydd allweddi sydd wedi'u marcio i'w trin fel Allweddi Personol yn cael eu rhestru yn yr adran Amgryptio Ben-i-Ben. Bydd y lleill ar gael y tu mewn i'r Rheolwr Allweddi.
+
+openpgp-passphrase-prompt-title = Mae angen cyfrinymadrodd
+
+#   $identity (String) - the id of the key being imported
+openpgp-passphrase-prompt = Rhowch y cyfrinymadrodd i ddatgloi'r allwedd ganlynol: { $key }
+
+openpgp-import-key-button =
+    .label = Dewis Ffeil i'w Mewnforio ...
+    .accesskey = D
+
+import-key-file = Mewnforio Ffeil Allwedd OpenPGP
+
+import-key-personal-checkbox =
+    .label = Trin yr allwedd hon fel Allwedd Bersonol
+
+gnupg-file = Ffeiliau GnuPG
+
+import-error-file-size = <b>Gwall!</b> Nid yw ffeiliau mwy na 5MB yn cael eu cefnogi.
+
+#   $error (String) - the reported error from the failed key import method
+import-error-failed = <b>Gwall!</b> Wedi methu mewnforio ffeil. { $error }
+
+#   $error (String) - the reported error from the failed key import method
+openpgp-import-keys-failed = <b>Gwall!</b> Wedi methu mewnforio allweddi. { $error }
+
+openpgp-import-identity-label = Hunaniaeth
+
+openpgp-import-fingerprint-label = Bysbrint
+
+openpgp-import-created-label = Crëwyd
+
+openpgp-import-bits-label = Didau
+
+openpgp-import-key-props =
+    .label = Priodweddau'r Allwedd
+    .accesskey = P
+
+## External Key section
+
+openpgp-external-key-title = Allwedd GnuPG Allanol
+
+openpgp-external-key-description = Ffurfweddu allwedd GnuPG allanol trwy nodi ID yr Allwedd
+
+openpgp-external-key-info = Yn ogystal, rhaid i chi ddefnyddio'r Rheolwr Allweddi i fewnforio a derbyn yr Allwedd Gyhoeddus gyfatebol.
+
+openpgp-external-key-warning = <b>Dim ond un Allwedd GnuPG allanol y gallwch chi ei ffurfweddu.</b> Bydd eich cofnod blaenorol yn cael ei ddisodli.
+
+openpgp-save-external-button = Cadw ID yr allwedd
+
+openpgp-external-key-label = ID Allwedd Gyfrinachol:
+
+openpgp-external-key-input =
+    .placeholder = 123456789341298340
diff --git a/l10n-cy/mail/messenger/openpgp/msgReadStatus.ftl b/l10n-cy/mail/messenger/openpgp/msgReadStatus.ftl
new file mode 100644
index 0000000000..6c0b6e00d2
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/msgReadStatus.ftl
@@ -0,0 +1,76 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Message Header Encryption Button
+
+message-header-show-security-info-key = D
+
+#   $type (String) - the shortcut key defined in the message-header-show-security-info-key
+message-security-button =
+    .title =
+        { PLATFORM() ->
+            [macos] Dangos Diogelwch Negeseuon (⌘ ⌥ { message-header-show-security-info-key })
+           *[other] Dangos Diogelwch Negeseuon (Ctrl+Alt+{ message-header-show-security-info-key }
+        }
+
+openpgp-view-signer-key =
+    .label = Gweld allwedd llofnodwr
+openpgp-view-your-encryption-key =
+    .label = Gweld eich allwedd dadgryptio
+openpgp-openpgp = OpenPGP
+
+openpgp-no-sig = Dim Llofnod Digidol
+openpgp-no-sig-info = Nid yw'r neges yn cynnwys llofnod digidol yr anfonwr. Mae absenoldeb y llofnod digidol yn golygu bod modd i'r neges ddod gan rywun sy'n cogio mai ei gyfeiriad e-bost yw hwn. Mae hefyd yn bosibl fod y neges wedi cael ei newid wrth deithio ar draws y rhwydwaith.
+openpgp-uncertain-sig = Llofnod Digidol Ansicr
+openpgp-invalid-sig = Llofnod Digidol Annilys
+openpgp-good-sig = Llofnod Digidol Da
+
+openpgp-sig-uncertain-no-key = Mae'r neges hon yn cynnwys llofnod digidol, ond mae'n ansicr a yw'n gywir. I wirio'r llofnod, mae angen i chi gael copi o allwedd gyhoeddus yr anfonwr.
+openpgp-sig-uncertain-uid-mismatch = Mae'r neges hon yn cynnwys llofnod digidol, ond canfuwyd diffyg cyfatebiaeth. Anfonwyd y neges o gyfeiriad e-bost nad yw'n cyd-fynd ag allwedd gyhoeddus y llofnodwr.
+openpgp-sig-uncertain-not-accepted = Mae'r neges hon yn cynnwys llofnod digidol, ond nid ydych wedi penderfynu eto a yw allwedd y llofnodwr yn dderbyniol i chi.
+openpgp-sig-invalid-rejected = Mae'r neges hon yn cynnwys llofnod digidol, ond rydych chi wedi penderfynu gwrthod allwedd y llofnodwr yn flaenorol.
+openpgp-sig-invalid-technical-problem = Mae'r neges hon yn cynnwys llofnod digidol, ond canfuwyd gwall technegol. Naill ai mae'r neges wedi'i llygru, neu mae'r neges wedi'i haddasu gan rywun arall.
+openpgp-sig-valid-unverified = Mae'r neges hon yn cynnwys llofnod digidol dilys o allwedd rydych chi eisoes wedi'i derbyn. Fodd bynnag, nid ydych wedi gwirio eto bod yr allwedd yn eiddo i'r anfonwr mewn gwirionedd.
+openpgp-sig-valid-verified = Mae'r neges hon yn cynnwys llofnod digidol dilys o allwedd wedi'i gwirio.
+openpgp-sig-valid-own-key = Mae'r neges hon yn cynnwys llofnod digidol dilys o'ch allwedd bersonol.
+
+openpgp-sig-key-id = ID allwedd llofnodwr: { $key }
+openpgp-sig-key-id-with-subkey-id = ID allwedd llofnodwr: { $key } (ID Is-allwedd: { $subkey })
+
+openpgp-enc-key-id = ID eich allwedd dadgryptio: { $key }
+openpgp-enc-key-with-subkey-id = ID eich allwedd dadgryptio: { $key } (ID Is-allwedd: { $subkey })
+
+openpgp-enc-none = Nid yw'r Neges wedi'i Hamgryptio
+openpgp-enc-none-label = Nid yw'r neges hon wedi'i hamgryptio cyn ei hanfon. Mae modd i eraill weld negeseuon sy'n cael eu hanfon ar draws y rhyngrwyd ac sydd heb eu hamgryptio.
+
+openpgp-enc-invalid-label = Nid Oes Modd Dadgryptio'r Neges
+openpgp-enc-invalid = Mae'r neges wedi'i hamgryptio cyn ei hanfon atoch, ond nid oes modd ei dadgryptio.
+
+openpgp-enc-clueless = Mae yna anawsterau anhysbys gyda'r neges wedi'i hamgryptio.
+
+openpgp-enc-valid-label = Mae'r Neges wedi'i Hamgryptio
+openpgp-enc-valid = Amgryptiwyd y neges hon cyn ei hanfon atoch. Mae amgryptio yn sicrhau mai dim ond y derbynwyr y bwriadwyd iddynt ddarllen y neges sy'n gallu.
+
+openpgp-unknown-key-id = Allwedd anhysbys
+
+openpgp-other-enc-additional-key-ids = Yn ogystal, amgryptiwyd y neges i berchnogion yr allweddi canlynol:
+openpgp-other-enc-all-key-ids = Amgryptiwyd y neges i berchnogion yr allweddi canlynol:
+
+openpgp-message-header-encrypted-ok-icon =
+    .alt = Dadgryptio yn llwyddiannus
+openpgp-message-header-encrypted-notok-icon =
+    .alt = Methodd y dadgriptio
+
+openpgp-message-header-signed-ok-icon =
+    .alt = Llofnod da
+# Mismatch icon is used for notok state as well
+openpgp-message-header-signed-mismatch-icon =
+    .alt = Llofnod gwael
+openpgp-message-header-signed-unknown-icon =
+    .alt = Statws llofnod anhysbys
+openpgp-message-header-signed-verified-icon =
+    .alt = Llofnod wedi'i wirio
+openpgp-message-header-signed-unverified-icon =
+    .alt = Llofnod heb ei wirio
diff --git a/l10n-cy/mail/messenger/openpgp/oneRecipientStatus.ftl b/l10n-cy/mail/messenger/openpgp/oneRecipientStatus.ftl
new file mode 100644
index 0000000000..ffde3f99f9
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/oneRecipientStatus.ftl
@@ -0,0 +1,58 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+openpgp-one-recipient-status-title =
+    .title = Diogelwch Negeseuon OpenPGP
+openpgp-one-recipient-status-status =
+    .label = Statws
+openpgp-one-recipient-status-key-id =
+    .label = ID Allwedd
+openpgp-one-recipient-status-created-date =
+    .label = Crëwyd
+openpgp-one-recipient-status-expires-date =
+    .label = Daw i ben
+openpgp-one-recipient-status-open-details =
+    .label = Agor manylion a golygu derbyniad...
+openpgp-one-recipient-status-discover =
+    .label = Darganfod allwedd newydd neu wedi'i diweddaru
+
+openpgp-one-recipient-status-instruction1 = I anfon neges wedi'i hamgryptio o ben-i-ben at dderbynnydd, mae angen i chi gael gafael ar ei allwedd gyhoeddus OpenPGP a'i nodi fel y'i derbyniwyd.
+openpgp-one-recipient-status-instruction2 = I gael eu allwedd gyhoeddus, eu mewnforio o e-bost y maent wedi'i anfon atoch ac sy'n ei gynnwys. Fel arall, gallwch geisio darganfod eu allwedd gyhoeddus ar gyfeiriadur.
+
+openpgp-key-own = Derbyniwyd (allwedd bersonol)
+openpgp-key-secret-not-personal = Ddim yn ddefnyddiadwy
+openpgp-key-verified = Derbyniwyd (dilyswyd)
+openpgp-key-unverified = Derbyniwyd (heb ei wirio)
+openpgp-key-undecided = Heb ei dderbyn (heb benderfynu)
+openpgp-key-rejected = Heb ei dderbyn (gwrthodwyd)
+openpgp-key-expired = Daeth i Ben
+
+openpgp-intro = Allweddi cyhoeddus sydd ar gael ar gyfer { $key }
+
+openpgp-pubkey-import-id = ID: { $kid }
+openpgp-pubkey-import-fpr = Bysbrint: { $fpr }
+
+openpgp-pubkey-import-intro =
+    { $num ->
+        [zero] Nid yw'r ffeil yn cynnwys allweddi cyhoeddus
+        [one] Mae'r ffeil yn cynnwys un allwedd gyhoeddus fel sy'n cael ei ddangos isod:
+        [two] Mae'r ffeil yn cynnwys { $num } allwedd gyhoeddus fel sy'n cael ei ddangos isod:
+        [few] Mae'r ffeil yn cynnwys { $num } allwedd gyhoeddus fel sy'n cael ei ddangos isod:
+        [many] Mae'r ffeil yn cynnwys { $num } allwedd gyhoeddus fel sy'n cael ei ddangos isod:
+       *[other] Mae'r ffeil yn cynnwys { $num } allwedd gyhoeddus fel sy'n cael ei ddangos isod:
+    }
+
+openpgp-pubkey-import-accept =
+    { $num ->
+        [zero] Ydych chi'n derbyn yr allweddi hyn ar gyfer gwirio llofnodion digidol ac ar gyfer amgryptio negeseuon?
+        [one] Ydych chi'n derbyn yr allwedd hon ar gyfer gwirio llofnodion digidol ac ar gyfer amgryptio negeseuon?
+        [two] Ydych chi'n derbyn yr allweddi hyn ar gyfer gwirio llofnodion digidol ac ar gyfer amgryptio negeseuon?
+        [few] Ydych chi'n derbyn yr allweddi hyn ar gyfer gwirio llofnodion digidol ac ar gyfer amgryptio negeseuon?
+        [many] Ydych chi'n derbyn yr allweddi hyn ar gyfer gwirio llofnodion digidol ac ar gyfer amgryptio negeseuon?
+       *[other] Ydych chi'n derbyn yr allweddi hyn ar gyfer gwirio llofnodion digidol ac ar gyfer amgryptio negeseuon?
+    }
+
+pubkey-import-button =
+    .buttonlabelaccept = Mewnforio
+    .buttonaccesskeyaccept = M
diff --git a/l10n-cy/mail/messenger/openpgp/openpgp-frontend.ftl b/l10n-cy/mail/messenger/openpgp/openpgp-frontend.ftl
new file mode 100644
index 0000000000..727018c813
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/openpgp-frontend.ftl
@@ -0,0 +1,64 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+openpgp-manage-keys-openpgp-cmd =
+    .label = Rheolwr Allweddi OpenPGP
+    .accesskey = R
+
+openpgp-ctx-decrypt-open =
+    .label = Dadgryptio ac Agor
+    .accesskey = D
+openpgp-ctx-decrypt-save =
+    .label = Dadgryptio a Chadw Fel…
+    .accesskey = C
+openpgp-ctx-import-key =
+    .label = Mewnforio Allwedd OpenPGP
+    .accesskey = M
+openpgp-ctx-verify-att =
+    .label = Gwirio Llofnod
+    .accesskey = G
+
+openpgp-has-sender-key = Mae'r neges hon yn honni ei bod yn cynnwys allwedd gyhoeddus OpenPGP yr anfonwr.
+openpgp-be-careful-new-key = Rhybudd: Mae'r allwedd gyhoeddus OpenPGP newydd yn y neges hon yn wahanol i'r allweddi cyhoeddus y gwnaethoch eu derbyn o'r blaen gan { $email }
+
+openpgp-import-sender-key =
+    .label = Mewnforio…
+
+openpgp-search-keys-openpgp =
+    .label = Darganfod Allweddi OpenPGP
+
+openpgp-missing-signature-key = Llofnodwyd y neges hon ag allwedd nad yw gennych chi eto.
+
+openpgp-search-signature-key =
+    .label = Darganfod…
+
+# Don't translate the terms "OpenPGP" and "MS-Exchange"
+openpgp-broken-exchange-opened = Mae hon yn neges OpenPGP gafodd ei llygru yn ôl pob golwg gan MS-Exchange ac nid oes modd ei hatgyweirio oherwydd iddi gael ei hagor o ffeil leol. Copïwch y neges i mewn i ffolder e-bost i roi cynnig ar ei hatgyweirio'n awtomatig.
+openpgp-broken-exchange-info = Neges OpenPGP yw hon a gafodd ei llygru yn ôl pob golwg gan MS-Exchange. Os na yw cynnwys y neges yn cael ei ddangos yn ôl y disgwyl, gallwch roi cynnig ar atgyweiriad awtomatig.
+openpgp-broken-exchange-repair =
+    .label = Atgyweirio neges
+openpgp-broken-exchange-wait = Arhoswch…
+
+openpgp-cannot-decrypt-because-mdc =
+    Neges wedi'i hamgryptio yw hon sy'n defnyddio hen fecanwaith bregus.
+    Gall fod wedi cael ei addasu wrth gael ei gludo, gyda'r bwriad o ddwyn ei gynnwys.
+    Er mwyn atal y risg hon, nid yw'r cynnwys yn cael ei ddangos.
+
+openpgp-cannot-decrypt-because-missing-key = Nid yw'r allwedd gyfrinachol sy'n ofynnol i ddadgryptio'r neges hon ar gael.
+
+openpgp-partially-signed =
+    Dim ond is-set o'r neges hon a lofnodwyd yn ddigidol gan ddefnyddio OpenPGP.
+    Os cliciwch y botwm gwirio, bydd y rhannau heb ddiogelwch yn cael eu cuddio, a bydd statws y llofnod digidol yn cael ei ddangos.
+
+openpgp-partially-encrypted =
+    Dim ond is-set o'r neges hon a amgryptiwyd gan ddefnyddio OpenPGP.
+    Nid yw rhannau darllenadwy o'r neges sy'n cael eu dangos eisoes wedi eu hamgryptio.
+    Os cliciwch y botwm dadgryptio, bydd cynnwys y rhannau wedi'u hamgryptio yn cael eu dangos.
+
+openpgp-reminder-partial-display = Nodyn i'ch atgoffa: Dim ond is-set o'r neges wreiddiol yw'r neges sy'n cael ei ddangos isod.
+
+openpgp-partial-verify-button = Gwirio
+openpgp-partial-decrypt-button = Dadgryptio
+
+openpgp-unexpected-key-for-you = Rhybudd: Mae'r neges hon yn cynnwys allwedd OpenPGP anhysbys sy'n cyfeirio at un o'ch cyfeiriadau e-bost chi eich hun. Os nad yw hwn yn un o'ch allweddi chi, gall fod yn ymgais i dwyllo gohebwyr eraill.
diff --git a/l10n-cy/mail/messenger/openpgp/openpgp.ftl b/l10n-cy/mail/messenger/openpgp/openpgp.ftl
new file mode 100644
index 0000000000..e825a283c2
--- /dev/null
+++ b/l10n-cy/mail/messenger/openpgp/openpgp.ftl
@@ -0,0 +1,767 @@
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+e2e-intro-description = I anfon negeseuon wedi'u hamgryptio neu wedi'u llofnodi'n ddigidol, mae angen i chi ffurfweddu technoleg amgryptio, naill ai OpenPGP neu S / MIME.
+e2e-intro-description-more = Dewiswch eich allwedd bersonol i alluogi defnyddio OpenPGP, neu'ch tystysgrif bersonol i alluogi defnyddio S/MIME. Ar gyfer allwedd neu dystysgrif bersonol chi sy'n berchen ar yr allwedd gyfrinachol gyfatebol.
+
+e2e-signing-description = Mae llofnod digidol yn caniatáu i dderbynwyr wirio bod y neges wedi'i hanfon gennych chi ac nad yw'r cynnwys wedi'i newid. Mae negeseuon amgryptiedig wedi eu llofnodi drwy ragosodiad.
+
+e2e-sign-message =
+    .label = Llofnodi negeseuon heb eu hamgryptio
+    .accesskey = h
+
+e2e-disable-enc =
+    .label = Analluogi amgryptio ar gyfer negeseuon newydd
+    .accesskey = A
+e2e-enable-enc =
+    .label = Galluogi amgryptio ar gyfer negeseuon newydd
+    .accesskey = G
+e2e-enable-description = Byddwch yn gallu analluogi amgryptio ar gyfer negeseuon unigol.
+
+e2e-advanced-section = Gosodiadau uwch
+e2e-attach-key =
+    .label = Atodwch fy allwedd gyhoeddus wrth ychwanegu llofnod digidol OpenPGP
+    .accesskey = A
+e2e-encrypt-subject =
+    .label = Amgryptio destun negeseuon OpenPGP
+    .accesskey = A
+e2e-encrypt-drafts =
+    .label = Cadw negeseuon drafft mewn fformat wedi'i amgryptio
+    .accesskey = C
+
+openpgp-key-user-id-label = Cyfrif / ID Defnyddiwr
+openpgp-keygen-title-label =
+    .title = Cynhyrchu Allwedd OpenPGP
+openpgp-cancel-key =
+    .label = Diddymu
+    .tooltiptext = Diddymu Cynhyrchu Allwedd
+openpgp-key-gen-expiry-title =
+    .label = Allwedd yn dod i ben
+openpgp-key-gen-expire-label = Allwedd yn dod i ben ymhen
+openpgp-key-gen-days-label =
+    .label = diwrnod
+openpgp-key-gen-months-label =
+    .label = mis
+openpgp-key-gen-years-label =
+    .label = b/mlynedd
+openpgp-key-gen-no-expiry-label =
+    .label = Nid yw'r allwedd yn dod i ben
+openpgp-key-gen-key-size-label = Maint yr allwedd
+openpgp-key-gen-console-label = Cynhyrchu Allwedd
+openpgp-key-gen-key-type-label = Math o allwedd
+openpgp-key-gen-key-type-rsa =
+    .label = RSA
+openpgp-key-gen-key-type-ecc =
+    .label = ECC (Cromlin Eliptig)
+openpgp-generate-key =
+    .label = Cynhyrchu allwedd
+    .tooltiptext = Yn cynhyrchu allwedd OpenPGP cydymffurfiol ar gyfer amgryptiad a/neu lofnodi
+openpgp-advanced-prefs-button-label =
+    .label = Uwch…
+openpgp-keygen-desc = <a data-l10n-name="openpgp-keygen-desc-link">SYLWCH: Gall cynhyrchu allweddol gymryd rhai munudau i'w gwblhau.</a> Peidiwch â gadael y rhaglen tra bo'r allwedd yn cael ei gynhyrchu. Bydd pori neu berfformio gweithrediadau disg-ddwys yn ystod cynhyrchu'r allwedd yn ailgyflenwi'r 'gronfa ar hap' ac yn cyflymu'r broses. Cewch eich rhybuddio pan fydd cynhyrchu'r allweddol wedi'i gwblhau.
+
+openpgp-key-created-label =
+    .label = Crëwyd
+
+openpgp-key-expiry-label =
+    .label = Dod i ben
+
+openpgp-key-id-label =
+    .label = ID Allwedd
+
+openpgp-cannot-change-expiry = Mae hwn yn allwedd gyda strwythur cymhleth, nid yw newid ei ddyddiad dod i ben yn cael ei gefnogi.
+
+openpgp-key-man-title =
+    .title = Rheolwr Allweddi OpenPGP
+openpgp-key-man-generate =
+    .label = Pâr Allweddi Newydd
+    .accesskey = P
+openpgp-key-man-gen-revoke =
+    .label = Tystysgrif Dirymu
+    .accesskey = D
+openpgp-key-man-ctx-gen-revoke-label =
+    .label = Cynhyrchu a Chadw Tystysgrif Dirymu
+
+openpgp-key-man-file-menu =
+    .label = Ffeil
+    .accesskey = F
+openpgp-key-man-edit-menu =
+    .label = Golygu
+    .accesskey = G
+openpgp-key-man-view-menu =
+    .label = Gweld
+    .accesskey = G
+openpgp-key-man-generate-menu =
+    .label = Cynhyrchu
+    .accesskey = C
+openpgp-key-man-keyserver-menu =
+    .label = Gweinydd Allweddi
+    .accesskey = G
+
+openpgp-key-man-import-public-from-file =
+    .label = Mewnforio Allwedd(i) Cyhoeddus o'r Ffeil
+    .accesskey = M
+openpgp-key-man-import-secret-from-file =
+    .label = Mewnforio Allwedd(i) Cyfrinachol o'r Ffeil
+openpgp-key-man-import-sig-from-file =
+    .label = Mewnforio Dirymiad(au) o'r Ffeil
+openpgp-key-man-import-from-clipbrd =
+    .label = Mewnforio Allwedd(i) o'r Clipfwrdd
+    .accesskey = C
+openpgp-key-man-import-from-url =
+    .label = Mewnforio Allwedd(i) o URL
+    .accesskey = U
+openpgp-key-man-export-to-file =
+    .label = Allforio Allwedd(i) Cyhoeddus i Ffeil
+    .accesskey = F
+openpgp-key-man-send-keys =
+    .label = Anfon Allwedd(i) Cyhoeddus Trwy E-bost
+    .accesskey = E
+openpgp-key-man-backup-secret-keys =
+    .label = Allwedd(i) Cyfrinachol Wrth Gefn I'w Ffeilio
+    .accesskey = G
+
+openpgp-key-man-discover-cmd =
+    .label = Darganfod Allweddi Ar-lein
+    .accesskey = D
+openpgp-key-man-discover-prompt = I ddarganfod allweddi OpenPGP ar-lein, ar weinydd allweddi neu ddefnyddio protocol WKD, rhowch naill ai gyfeiriad e-bost neu ID allwedd.
+openpgp-key-man-discover-progress = Chwilio…
+
+openpgp-key-copy-key =
+    .label = Copïo Allwedd Gyhoeddus
+    .accesskey = G
+
+openpgp-key-export-key =
+    .label = Allforio Allwedd Gyhoeddus I'r Ffeil
+    .accesskey = A
+
+openpgp-key-backup-key =
+    .label = Gwneud Copi wrth Gefn o Allwedd Gyfrinachol i Ffeil
+    .accesskey = G
+
+openpgp-key-send-key =
+    .label = Anfon Allwedd Gyhoeddus Trwy E-bost
+    .accesskey = A
+
+openpgp-key-man-copy-key-ids =
+    .label =
+        { $count ->
+            [zero] Copïo IDau Allwedd i'r Clipfwrdd
+            [one] Copïo ID Allwedd i'r Clipfwrdd
+            [two] Copïo ID Allwedd i'r Clipfwrdd
+            [few] Copïo ID Allwedd i'r Clipfwrdd
+            [many] Copïo ID Allwedd i'r Clipfwrdd
+           *[other] Copïo ID Allwedd i'r Clipfwrdd
+        }
+    .accesskey = I
+
+openpgp-key-man-copy-fprs =
+    .label =
+        { $count ->
+            [zero] Copïo Bysbrintiau i'r Clipfwrdd
+            [one] Copïo Bysbrint i'r Clipfwrdd
+            [two] Copïo Bysbrint i'r Clipfwrdd
+            [few] Copïo Bysbrint i'r Clipfwrdd
+            [many] Copïo Bysbrint i'r Clipfwrdd
+           *[other] Copïo Bysbrint i'r Clipfwrdd
+        }
+    .accesskey = B
+
+openpgp-key-man-copy-to-clipboard =
+    .label =
+        { $count ->
+            [zero] Copïo Allweddi Cyhoeddus I'r Clipfwrdd
+            [one] Copïo Allwedd Gyhoeddus I'r Clipfwrdd
+            [two] Copïo Allwedd Gyhoeddus I'r Clipfwrdd
+            [few] Copïo Allwedd Gyhoeddus I'r Clipfwrdd
+            [many] Copïo Allwedd Gyhoeddus I'r Clipfwrdd
+           *[other] Copïo Allwedd Gyhoeddus I'r Clipfwrdd
+        }
+    .accesskey = A
+
+openpgp-key-man-ctx-expor-to-file-label =
+    .label = Allforio Allweddi i Ffeil
+
+openpgp-key-man-ctx-copy =
+    .label = Copïo
+    .accesskey = C
+
+openpgp-key-man-ctx-copy-fprs =
+    .label =
+        { $count ->
+            [zero] Bysbrintiau
+            [one] Bysbrint
+            [two] Bysbrint
+            [few] Bysbrint
+            [many] Bysbrint
+           *[other] Bysbrint
+        }
+    .accesskey = B
+
+openpgp-key-man-ctx-copy-key-ids =
+    .label =
+        { $count ->
+            [zero] ID Allwedd
+            [one] ID Allwedd
+            [two] ID Allwedd
+            [few] ID Allwedd
+            [many] ID Allwedd
+           *[other] ID Allwedd
+        }
+    .accesskey = D
+
+openpgp-key-man-ctx-copy-public-keys =
+    .label =
+        { $count ->
+            [zero] Allweddi Cyhoeddus
+            [one] Allwedd Gyhoeddus
+            [two] Allwedd Gyhoeddus
+            [few] Allwedd Gyhoeddus
+            [many] Allwedd Gyhoeddus
+           *[other] Allwedd Gyhoeddus
+        }
+    .accesskey = y
+
+openpgp-key-man-close =
+    .label = Cau
+openpgp-key-man-reload =
+    .label = Ail-lwytho Storfa Allweddi
+    .accesskey = S
+openpgp-key-man-change-expiry =
+    .label = Newid Dyddiad Dod i Ben
+    .accesskey = N
+openpgp-key-man-refresh-online =
+    .label = Adnewyddu Ar-lein
+    .accesskey = d
+openpgp-key-man-ignored-ids =
+    .label = Cyfeiriadau e-bost
+openpgp-key-man-del-key =
+    .label = Dileu Allwedd(i)
+    .accesskey = D
+openpgp-delete-key =
+    .label = Dileu Allwedd
+    .accesskey = A
+openpgp-key-man-revoke-key =
+    .label = Dirymu Allwedd
+    .accesskey = i
+openpgp-key-man-key-props =
+    .label = Priodweddau Allweddi
+    .accesskey = P
+openpgp-key-man-key-more =
+    .label = Rhagor
+    .accesskey = R
+openpgp-key-man-view-photo =
+    .label = ID Llun
+    .accesskey = L
+openpgp-key-man-ctx-view-photo-label =
+    .label = Gweld ID Llun
+openpgp-key-man-show-invalid-keys =
+    .label = Dangos allweddi annilys
+    .accesskey = D
+openpgp-key-man-show-others-keys =
+    .label = Dangos Allweddi Gan Bobl Eraill
+    .accesskey = B
+openpgp-key-man-user-id-label =
+    .label = Enw
+openpgp-key-man-fingerprint-label =
+    .label = Bysbrint
+openpgp-key-man-select-all =
+    .label = Dewis Pob Allwedd
+    .accesskey = P
+openpgp-key-man-empty-tree-tooltip =
+    .label = Rhowch dermau chwilio yn y blwch uchod
+openpgp-key-man-nothing-found-tooltip =
+    .label = Nid oes unrhyw allweddi yn cyd-fynd â'ch chwilio
+openpgp-key-man-please-wait-tooltip =
+    .label = Arhoswch tra bod allweddi yn cael eu llwytho...
+
+openpgp-key-man-filter-label =
+    .placeholder = Chwilio am allweddi
+
+openpgp-key-man-select-all-key =
+    .key = P
+openpgp-key-man-key-details-key =
+    .key = I
+
+openpgp-ign-addr-intro = Rydych yn derbyn defnyddio'r allwedd hon ar gyfer y cyfeiriadau e-bost dethol canlynol:
+
+openpgp-key-details-doc-title = Priodweddau Allweddi
+openpgp-key-details-signatures-tab =
+    .label = Ardystiadau
+openpgp-key-details-structure-tab =
+    .label = Strwythur
+openpgp-key-details-uid-certified-col =
+    .label = ID Defnyddiwr / Ardystiedig gan
+openpgp-key-details-key-id-label = ID Allwedd
+openpgp-key-details-user-id3-label = Perchennog Honedig Allwedd
+openpgp-key-details-id-label =
+    .label = ID
+openpgp-key-details-key-type-label = Math
+openpgp-key-details-key-part-label =
+    .label = Rhan Allwedd
+
+openpgp-key-details-attr-ignored = Rhybudd: Efallai na fydd yr allwedd hon yn gweithio yn ôl y disgwyl, oherwydd bod rhai o'i phriodweddau'n anniogel ac y mae modd eu hanwybyddu.
+openpgp-key-details-attr-upgrade-sec = Dylech uwchraddio'r priodweddau anniogel.
+openpgp-key-details-attr-upgrade-pub = Dylech ofyn i berchennog yr allwedd hon i uwchraddio'r priodweddau anniogel.
+
+openpgp-key-details-upgrade-unsafe =
+    .label = Uwchraddio Priodweddau Anniogel
+    .accesskey = U
+
+openpgp-key-details-upgrade-ok = Uwchraddiwyd yr allwedd yn llwyddiannus. Dylech rannu'r allwedd gyhoeddus wedi'i huwchraddio gyda'ch gohebwyr.
+
+openpgp-key-details-algorithm-label =
+    .label = Algorithm
+openpgp-key-details-size-label =
+    .label = Maint
+openpgp-key-details-created-label =
+    .label = Crëwyd
+openpgp-key-details-created-header = Crëwyd
+openpgp-key-details-expiry-label =
+    .label = Dod i ben
+openpgp-key-details-expiry-header = Dod i ben
+openpgp-key-details-usage-label =
+    .label = Defnydd
+openpgp-key-details-fingerprint-label = Bysbrint
+openpgp-key-details-legend-secret-missing = Ar gyfer bysellau sydd wedi'u marcio â (!) nid yw'r fysell gyfrinachol ar gael.
+openpgp-key-details-sel-action =
+    .label = Dewis gweithred...
+    .accesskey = g
+openpgp-card-details-close-window-label =
+    .buttonlabelaccept = Cau
+openpgp-acceptance-label =
+    .label = Eich Derbyn
+openpgp-acceptance-rejected-label =
+    .label = Na, gwrthodwch yr allwedd hon.
+openpgp-acceptance-undecided-label =
+    .label = Ddim eto, efallai yn hwyrach.
+openpgp-acceptance-unverified-label =
+    .label = Iawn, ond nid wyf wedi gwirio mai hwn yw'r allwedd gywir.
+openpgp-acceptance-verified-label =
+    .label = Ydw, rydw i wedi gwirio yn bersonol bod gan yr allwedd hon yr bysbrint cywir.
+key-accept-personal =
+    Yn yr allwedd hon, mae gennych rhan gyhoeddus a rhan gyfrinachol. Gallwch ei defnyddio fel allwedd bersonol.
+    Os rhoddwyd yr allwedd hon i chi gan rywun arall, yna peidiwch â'i defnyddio fel allwedd bersonol.
+openpgp-personal-no-label =
+    .label = Na, peidio'i defnyddio fel fy allwedd bersonol.
+openpgp-personal-yes-label =
+    .label = Iawn, trin yr allwedd hon fel allwedd bersonol.
+
+openpgp-copy-cmd-label =
+    .label = Copïo
+
+## e2e encryption settings
+
+#   $identity (String) - the email address of the currently selected identity
+openpgp-description-no-key = Nid oes gan { -brand-short-name } allwedd OpenPGP personol ar gyfer <b>{ $identity }</b>
+
+#   $count (Number) - the number of configured keys associated with the current identity
+#   $identity (String) - the email address of the currently selected identity
+openpgp-description-has-keys =
+    { $count ->
+        [zero] Mae { -brand-short-name } wedi canfod { $count } allwedd OpenPGP personol sy'n gysylltiedig â <b>{ $identity }</b>
+        [one] Mae { -brand-short-name } wedi canfod { $count } allwedd OpenPGP personol sy'n gysylltiedig â <b>{ $identity }</b>
+        [two] Mae { -brand-short-name } wedi canfod { $count } allwedd OpenPGP personol sy'n gysylltiedig â <b>{ $identity }</b>
+        [few] Mae { -brand-short-name } wedi canfod { $count } allwedd OpenPGP personol sy'n gysylltiedig â <b>{ $identity }</b>
+        [many] Mae { -brand-short-name } wedi canfod { $count } allwedd OpenPGP personol sy'n gysylltiedig â <b>{ $identity }</b>
+       *[other] Mae { -brand-short-name } wedi canfod { $count } allwedd OpenPGP personol sy'n gysylltiedig â <b>{ $identity }</b>
+    }
+
+#   $key (String) - the currently selected OpenPGP key
+openpgp-selection-status-have-key = Mae eich ffurfweddiad cyfredol yn defnyddio ID allwedd <b>{ $key }</b>
+
+#   $key (String) - the currently selected OpenPGP key
+openpgp-selection-status-error = Mae eich ffurfweddiad cyfredol yn defnyddio ID allwedd <b>{ $key }</b>, sydd wedi dod i ben.
+
+openpgp-add-key-button =
+    .label = Ychwanegu Allwedd…
+    .accesskey = Y
+
+e2e-learn-more = Dysgu rhagor
+
+openpgp-keygen-success = Allwedd OpenPGP wedi'i chreu'n llwyddiannus!
+
+openpgp-keygen-import-success = Allweddi OpenPGP wedi'u mewnforio yn llwyddiannus!
+
+openpgp-keygen-external-success = ID Allwedd GnuPG Allanol wedi'i chadw!
+
+## OpenPGP Key selection area
+
+openpgp-radio-none =
+    .label = Dim
+
+openpgp-radio-none-desc = Peidiwch â defnyddio OpenPGP ar gyfer yr hunaniaeth hon.
+
+openpgp-radio-key-not-usable = Nid yw'r allwedd hon yn ddefnyddiadwy fel allwedd bersonol, oherwydd mae'r allwedd gyfrinachol ar goll!
+openpgp-radio-key-not-accepted = I ddefnyddio'r allwedd hon mae'n rhaid i chi ei chymeradwyo fel allwedd bersonol!
+openpgp-radio-key-not-found = Nid oedd modd canfod yr allwedd hon! Os ydych am ei defnyddio rhaid i chi ei mewnforio i { -brand-short-name }.
+
+#   $key (String) - the expiration date of the OpenPGP key
+openpgp-radio-key-expires = Yn dod i ben ar: { $date }
+
+#   $key (String) - the expiration date of the OpenPGP key
+openpgp-radio-key-expired = Wedi dod i ben ar: { $date }
+
+openpgp-key-expires-within-6-months-icon =
+    .title = Mae'r allwedd yn dod i ben o fewn 6 mis
+
+openpgp-key-has-expired-icon =
+    .title = Daeth yr allwedd i ben
+
+openpgp-key-expand-section =
+    .tooltiptext = Rhagor o wybodaeth
+
+openpgp-key-revoke-title = Dirymu Allwedd
+
+openpgp-key-edit-title = Newid Allwedd OpenPGP
+
+openpgp-key-edit-date-title = Ymestyn Dyddiad Dod i Ben
+
+openpgp-manager-description = Defnyddiwch y Rheolwr Allweddi OpenPGP i weld a rheoli allweddi cyhoeddus eich gohebwyr a'r holl allweddi eraill nad ydynt wedi'u rhestru uchod.
+
+openpgp-manager-button =
+    .label = Rheolwr Allwedd OpenPGP
+    .accesskey = R
+
+openpgp-key-remove-external =
+    .label = Dileu ID Allwedd Allanol
+    .accesskey = D
+
+key-external-label = Allwedd GnuPG Allanol
+
+# Strings in keyDetailsDlg.xhtml
+key-type-public = allwedd gyhoeddus
+key-type-primary = allwedd gynradd
+key-type-subkey = is-allwedd
+key-type-pair = pâr o allweddi (allwedd gyfrinachol ac allwedd gyhoeddus)
+key-expiry-never = byth
+key-usage-encrypt = Amgryptio
+key-usage-sign = Llofnodi
+key-usage-certify = Tystio
+key-usage-authentication = Dilysu
+key-does-not-expire = Nid yw'r allwedd yn dod i ben
+key-expired-date = Daeth yr allwedd i ben ar { $keyExpiry }
+key-expired-simple = Mae'r allwedd wedi dod i ben
+key-revoked-simple = Mae'r allwedd wedi'i dirymu
+key-do-you-accept = Ydych chi'n derbyn yr allwedd hon ar gyfer gwirio llofnodion digidol ac ar gyfer amgryptio negeseuon?
+key-verification = Dilyswch bysbrint yr allwedd gan ddefnyddio sianel gyfathrebu ddiogel ar wahân i e-bost i wneud yn siŵr mai dyma allwedd go iawn { $addr }.
+
+# Strings enigmailMsgComposeOverlay.js
+cannot-use-own-key-because = Methu anfon y neges, oherwydd mae problem gyda'ch allwedd bersonol. { $problem }
+cannot-encrypt-because-missing = Methu anfon y neges hon gydag amgryptio pen-i-ben, oherwydd mae problemau gydag allweddi'r derbynwyr canlynol: { $problem }
+window-locked = Mae'r ffenestr gyfansoddi wedi'i chloi; anfon wedi'i ddiddymu
+
+# Strings in mimeDecrypt.jsm
+mime-decrypt-encrypted-part-concealed-data = Mae hon yn rhan o neges wedi'i hamgryptio. Mae angen i chi ei hagor mewn ffenestr ar wahân trwy glicio ar yr atodiad.
+
+# Strings in keyserver.jsm
+keyserver-error-aborted = Ataliwyd
+keyserver-error-unknown = Digwyddodd gwall anhysbys
+keyserver-error-server-error = Adroddodd y gweinydd allweddi wall.
+keyserver-error-import-error = Wedi methu mewnforio'r allwedd wedi'i llwytho i lawr.
+keyserver-error-unavailable = Nid yw'r gweinydd allweddi ar gael.
+keyserver-error-security-error = Nid yw'r gweinydd allweddi'n cefnogi mynediad wedi'i amgryptio.
+keyserver-error-certificate-error = Nid yw tystysgrif y gweinydd allweddi'n ddilys.
+keyserver-error-unsupported = Nid yw'r gweinydd allweddi'n cael ei gynnal
+
+# Strings in mimeWkdHandler.jsm
+wkd-message-body-req =
+    Prosesodd eich darparwr e-bost eich cais i lwytho'ch allwedd gyhoeddus i fyny i Gyfeiriadur Allwedd Gwe OpenPGP.
+    Cadarnhewch i gwblhau cyhoeddi eich allwedd gyhoeddus.
+wkd-message-body-process =
+    E-bost yw hwn sy'n gysylltiedig â'r prosesu awtomatig i lwytho'ch allwedd gyhoeddus i fyny i Gyfeiriadur Allwedd Gwe OpenPGP.
+    Nid oes angen i chi gymryd unrhyw gamau â llaw ar hyn o bryd.
+
+# Strings in persistentCrypto.jsm
+converter-decrypt-body-failed =
+    Methu dadgryptio neges gyda'r pwnc
+    { $subject }.
+    Ydych chi am geisio eto gyda chyfrinair gwahanol neu a ydych chi am hepgor y neges?
+
+# Strings filters.jsm
+filter-folder-required = Rhaid dewis ffolder targed.
+filter-decrypt-move-warn-experimental =
+    Rhybudd - gall y weithred hidlo "Dadgryptio yn barhaol" arwain at negeseuon wedi'u dinistrio.
+    Rydym yn argymell yn gryf eich bod yn gyntaf yn rhoi cynnig ar yr hidlydd "Creu Copi wedi'i ddadgryptio", profi'r canlyniad yn ofalus, a dim ond ar ôl i chi fod yn fodlon â'r canlyniad yn dechrau defnyddio'r hidlydd.
+filter-term-pgpencrypted-label = Amgryptio OpenPGP
+filter-key-required = Rhaid dewis allwedd derbynnydd.
+filter-key-not-found = Methu cnfod allwedd amgryptio ar gyfer '{ $desc }'.
+filter-warn-key-not-secret =
+    Rhybudd - mae'r weithred hidlo "Amgryptio i allwedd" yn disodli'r derbynwyr.
+    Os nad oes gennych yr allwedd gyfrinachol ar gyfer '{ $desc }' fyddwch chi ddim yn gallu darllen yr e-byst bellach.
+
+# Strings filtersWrapper.jsm
+filter-decrypt-move-label = Dadgryptio yn barhaol (OpenPGP)
+filter-decrypt-copy-label = Creu Copi wedi'i ddadgryptio (OpenPGP)
+filter-encrypt-label = Amgryptio i allwedd (OpenPGP)
+
+# Strings in enigmailKeyImportInfo.js
+import-info-title =
+    .title = Llwyddiant! Allweddi wedi'u mewnforio
+import-info-bits = Didau
+import-info-created = Crëwyd
+import-info-fpr = Bysbrint
+import-info-details = Gweld Manylion a rheoli derbyniad allweddi
+import-info-no-keys = Dim allweddi wedi'u mewnforio.
+
+# Strings in enigmailKeyManager.js
+import-from-clip = Hoffech chi fewnforio rhywfaint o allweddi o'r clipfwrdd?
+import-from-url = Llwytho allwedd gyhoeddus i lawr o'r URL hwn:
+copy-to-clipbrd-failed = Methu copïo'r allweddi hyn i'r clipfwrdd.
+copy-to-clipbrd-ok = Copïwyd allweddi i'r clipfwrdd
+delete-secret-key =
+    RHYBUDD: Rydych chi ar fin dileu allwedd gyfrinachol!
+    
+    Os byddwch yn dileu eich allwedd gyfrinachol, ni fydd modd i chi ddadgryptio unrhyw negeseuon sydd wedi'u hamgryptio ar gyfer yr allwedd honno bellach, ac ni fyddwch yn gallu ei dirymu.
+    
+    Ydych chi wir eisiau DILEU'R allwedd gyfrinachol a'r allwedd gyhoeddus
+    '{ $userId }'?
+delete-mix =
+    RHYBUDD: Rydych chi ar fin dileu allwedd gyfrinachol!
+    Os byddwch yn dileu eich allwedd gyfrinachol, ni fydd modd i chi ddadgryptio unrhyw negeseuon sydd wedi'u hamgryptio ar gyfer yr allwedd honno bellach.
+    Ydych chi wir eisiau DILEU'R allwedd gyfrinachol a'r un gyhoeddus?
+delete-pub-key =
+    Ydych chi eisiau dileu'r allwedd gyhoeddus
+    '{ $userId }'?
+delete-selected-pub-key = Ydych chi eisiau dileu'r allwedd gyhoeddus'?
+refresh-all-question = Nid ydych wedi dewis unrhyw allwedd. Hoffech chi adnewyddu POB allwedd?
+key-man-button-export-sec-key = &Allforio Allweddi Cyfrinachol
+key-man-button-export-pub-key = Allforion Allweddi &Cyhoeddus yn Unig
+key-man-button-refresh-all = Adnewyddu &Pob Allwedd
+key-man-loading-keys = Llwytho allweddi, arhoswch...
+ascii-armor-file = Ffeiliau Arfogaeth ASCII (* .asc)
+no-key-selected = Dylech ddewis o leiaf un allwedd er mwyn cyflawni'r weithred hon
+export-to-file = Allforio Allwedd Gyhoeddus i Ffeil
+export-keypair-to-file = Allforio Allwedd Gyfrinachol a Chyhoeddus i Ffeil
+export-secret-key = Ydych chi am gynnwys yr allwedd gyfrinachol yn y ffeil allwedd OpenPGP sydd wedi'i chadw?
+save-keys-ok = Cadwyd yr allweddi'n llwyddiannus
+save-keys-failed = Methodd cadw'r allweddi
+default-pub-key-filename = Allweddi cyhoeddus wedi'u hallforio
+default-pub-sec-key-filename = Copi wrth gefn o allweddi cyfrinachol
+refresh-key-warn = Rhybudd: yn dibynnu ar nifer yr allweddi a chyflymder y cysylltiad, gall adnewyddu'r holl allweddi fod yn broses eithaf hir!
+preview-failed = Methu darllen ffeil allwedd gyhoeddus.
+general-error = Gwall: { $reason }
+dlg-button-delete = &Dileu
+
+## Account settings export output
+
+openpgp-export-public-success = <b> Allforiwyd Allwedd Gyhoeddus yn llwyddiannus!</b>
+openpgp-export-public-fail = <b>Methu allforio'r allwedd gyhoeddus a ddewiswyd!</b>
+
+openpgp-export-secret-success = <b>Allforiwyd Allwedd Gyfrinachol yn llwyddiannus!</b>
+openpgp-export-secret-fail = <b>Methu allforio'r allwedd gyfrinachol a ddewiswyd!</b>
+
+# Strings in keyObj.jsm
+key-ring-pub-key-revoked = Mae'r allwedd { $userId } (ID allwedd { $keyId }) wedi'i dirymu.
+key-ring-pub-key-expired = Mae'r allwedd { $userId } (ID allwedd { $keyId }) wedi dod i ben.
+key-ring-no-secret-key = Nid yw'n ymddangos bod gennych yr allwedd gyfrinachol ar gyfer { $userId } (ID allwedd { $keyId }) ar eich cylch allweddi; nid oes modd i chi ddefnyddio'r allwedd ar gyfer llofnodi.
+key-ring-pub-key-not-for-signing = Nid oed modd defnyddio'r allwedd { $userId } (ID allweddl { $keyId } ar gyfer llofnodi.
+key-ring-pub-key-not-for-encryption = Nid oed modd defnyddio'r allwedd { $userId } (ID allweddl { $keyId } ar gyfer amgryptio.
+key-ring-sign-sub-keys-revoked = Mae'r holl is-allweddi lofnodi allwedd { $userId } (ID allweddl { $keyId }) yn cael eu dirymu.
+key-ring-sign-sub-keys-expired = Mae'r holl is-allweddi lofnodi allwedd { $userId } (ID allweddl { $keyId }) wedi dod i ben.
+key-ring-enc-sub-keys-revoked = Mae pob is-allwedd amgryptio allwedd { $userId } (ID allwedd { $keyId }) yn cael ei ddirymu.
+key-ring-enc-sub-keys-expired = Mae pob is-allwedd amgryptio allwedd { $userId } (ID allwedd { $keyId }) wedi dod i ben.
+
+# Strings in gnupg-keylist.jsm
+keyring-photo = Llun
+user-att-photo = Priodoledd defnyddiwr (delwedd JPEG)
+
+# Strings in key.jsm
+already-revoked = Mae'r allwedd hon eisoes wedi'i dirymu.
+
+#   $identity (String) - the id and associated user identity of the key being revoked
+revoke-key-question =
+    Rydych chi ar fin dirymu'r allwedd '{ $identity }'.
+    Ni fydd modd i chi llofnodi gyda'r allwedd hon mwyach, ac ar ôl ei dosbarthu, ni fydd eraill yn gallu amgryptio gyda'r allwedd honno mwyach. Gallwch barhau i ddefnyddio'r allwedd i ddadgryptio hen negeseuon.
+    Ydych chi am barhau?
+
+#   $keyId (String) - the id of the key being revoked
+revoke-key-not-present =
+    Nid oes gennych allwedd (0x { $keyId }) sy'n cyfateb i'r dystysgrif ddirymu hon!
+    Os ydych wedi colli'ch allwedd, rhaid i chi ei fewnforio (e.e. o weinydd allweddi) cyn mewnforio'r dystysgrif ddirymu!
+
+#   $keyId (String) - the id of the key being revoked
+revoke-key-already-revoked = Mae'r allwedd 0x { $keyId } eisoes wedi'i dirymu.
+
+key-man-button-revoke-key = &Dirymu Allwedd
+
+openpgp-key-revoke-success = Dirymwyd yr allwedd yn llwyddiannus.
+
+after-revoke-info =
+    Mae'r allwedd wedi'i dirymu.
+    Rhannwch yr allwedd gyhoeddus hon eto, trwy ei hanfon trwy e-bost, neu trwy ei llwytho i weinyddion allweddi, i adael i eraill wybod eich bod wedi dirymu'ch allwedd.
+    Cyn gynted ag y bydd y feddalwedd sy'n cael ei ddefnyddio gan bobl eraill yn gwybod am y dirymiad, bydd yn rhoi'r gorau i ddefnyddio'ch hen allwedd.
+    Os ydych chi'n defnyddio allwedd newydd ar gyfer yr un cyfeiriad e-bost, a'ch bod chi'n atodi'r allwedd gyhoeddus newydd i e-byst rydych chi'n eu hanfon, yna bydd gwybodaeth am eich hen allwedd wedi'i dirymu yn cael ei chynnwys yn awtomatig.
+
+# Strings in keyRing.jsm & decryption.jsm
+key-man-button-import = &Mewnforio
+
+delete-key-title = Dileu Allwedd OpenPGP
+
+delete-external-key-title = Tynnwch yr Allwedd GnuPG Allanol
+
+delete-external-key-description = Ydych chi am dynnu'r ID yr allwedd GnuPG Allanol hwn?
+
+key-in-use-title = Allwedd OpenPGP sy'n cael ei defnyddio ar hyn o bryd
+
+delete-key-in-use-description = Methu parhau! Mae'r allwedd rydych wedi'i dewis i'w dileu yn cael ei defnyddio ar hyn o bryd gan yr hunaniaeth hon. Dewiswch allwedd wahanol, neu dewiswch ddim, a cheisiwch eto.
+
+revoke-key-in-use-description = Methu parhau! Mae'r allwedd rydych wedi'i dewis i'w dileu yn cael ei defnyddio ar hyn o bryd gan yr hunaniaeth hon. Dewiswch allwedd wahanol, neu dewiswch ddim, a cheisiwch eto.
+
+# Strings used in errorHandling.jsm
+key-error-key-spec-not-found = Nid oes modd cydweddu'r cyfeiriad e-bost '{ $keySpec }' ag allwedd ar eich cylch allweddi.
+key-error-key-id-not-found = Nid oes modd dod o hyd i ID yr allwedd wedi'i ffurfweddu '{ $keySpec }' ar eich cylch allweddi.
+key-error-not-accepted-as-personal = Nid ydych wedi cadarnhau mai'r allwedd gydag ID '{ $keySpec }' yw eich allwedd bersonol.
+
+# Strings used in enigmailKeyManager.js & windows.jsm
+need-online = Nid yw'r swyddogaeth rydych chi wedi'i dewis ar gael yn y modd all-lein. Ewch ar-lein a rhoi cynnig arall arni.
+
+# Strings used in keyRing.jsm & keyLookupHelper.jsm
+no-key-found2 = Nid oeddwn yn gallu canfod unrhyw allwedd sy'n cyfateb i'r meini prawf chwilio penodol yna.
+no-update-found = Mae gennych eisoes yr allweddi a ddarganfuwyd ar-lein.
+
+# Strings used in keyRing.jsm & GnuPGCryptoAPI.jsm
+fail-key-extract = Gwall - methodd y gorchymyn echdynnu allwedd
+
+# Strings used in keyRing.jsm
+fail-cancel = Gwall - Allwedd yn cael ei ddiddymu gan y defnyddiwr
+not-first-block = Gwall - Y bloc OpenPGP cyntaf nid bloc allwedd gyhoeddus
+import-key-confirm = Mewnforio allwedd(i) cyhoeddus wedi'u mewnblannu yn y neges?
+fail-key-import = Gwall - methodd mewnforio allweddi
+file-write-failed = Methwyd ysgrifennu at ffeil { $output }
+no-pgp-block = Gwall - Heb ddarganfod bloc data arfogaeth dilys OpenPGP
+confirm-permissive-import = Methodd y mewnforio. Efallai bod yr allwedd rydych chi'n ceisio ei fewnforio yn llygredig neu'n defnyddio priodoleddau anhysbys. Hoffech chi geisio mewnforio'r rhannau sy'n gywir? Gall hyn arwain at fewnforio allweddi anghyflawn ac nad oes modd eu defnyddio.
+
+# Strings used in trust.jsm
+key-valid-unknown = anhysbys
+key-valid-invalid = annilys
+key-valid-disabled = analluogwyd
+key-valid-revoked = dirymwyd
+key-valid-expired = daeth i ben
+key-trust-untrusted = di-ymddiried
+key-trust-marginal = ymylol
+key-trust-full = ymddiried ynddo
+key-trust-ultimate = eithaf
+key-trust-group = (grŵp)
+
+# Strings used in commonWorkflows.js
+import-key-file = Mewnforio Ffeil Allwedd OpenPGP
+import-rev-file = Mewnforio Ffeil Dirymu OpenPGP
+gnupg-file = Ffeiliau GnuPG
+import-keys-failed = Methodd mewnforio'r allweddi
+passphrase-prompt = Rhowch yr cyfrinymadrodd sy'n datgloi'r allwedd ganlynol: { $key }
+file-to-big-to-import = Mae'r ffeil hon yn rhy fawr. Peidiwch â mewnforio set fawr o allweddi ar unwaith.
+
+# Strings used in enigmailKeygen.js
+save-revoke-cert-as = Creu a Chadw Tystysgrif Dirymu
+revoke-cert-ok = Mae'r dystysgrif ddirymu wedi'i chreu'n llwyddiannus. Gallwch ei ddefnyddio i annilysu eich allwedd gyhoeddus, e.e. rhag ofn y byddwch yn colli'ch allwedd gyfrinachol.
+revoke-cert-failed = Nid oedd modd creu'r dystysgrif ddirymu.
+gen-going = Wrthi'n cynhyrchu allwedd!
+keygen-missing-user-name = Nid oes enw wedi'i nodi ar gyfer y cyfrif/hunaniaeth hon. Rhowch werth yn y maes   "Eich enw" yn yng ngosodiadau'r cyfrif.
+expiry-too-short = Rhaid i'ch allwedd fod yn ddilys am o leiaf un diwrnod.
+expiry-too-long = Nid oes modd i chi greu allwedd sy'n dod i ben mewn mwy na 100 mlynedd.
+key-confirm = Cynhyrchu allwedd gyhoeddus a chyfrinachol ar gyfer '{ $id }'?
+key-man-button-generate-key = &Cynhyrchu Allwedd
+key-abort = Atal cynhyrchu allwedd?
+key-man-button-generate-key-abort = &Atal Cynhyrchu Allwedd?
+key-man-button-generate-key-continue = &Parhau i Gynhyrchu Allweddi
+
+# Strings used in enigmailMessengerOverlay.js
+
+failed-decrypt = Gwall - methodd y dadgryptio
+fix-broken-exchange-msg-failed = Heb lwyddo i atgyweirio neges.
+
+attachment-no-match-from-signature = Methu cydweddu ffeil llofnod '{ $attachment }' ag atodiad
+attachment-no-match-to-signature = Methu cydweddu ffeil llofnod '{ $attachment }' â ffeil llofnod
+signature-verified-ok = Gwiriwyd y llofnod ar gyfer atodiad { $attachment } yn llwyddiannus
+signature-verify-failed = Methwyd gwirio y llofnod ar gyfer atodiad { $attachment }
+decrypt-ok-no-sig =
+    Rhybudd
+    Bu'r dadgryptio yn llwyddiant ond nid oedd modd gwirio'r llofnod yn iawn
+msg-ovl-button-cont-anyway = &Parhau Beth bynnag
+enig-content-note = *Nid yw atodiadau i'r neges hon wedi'u llofnodi na'u hamgryptio *
+
+# Strings used in enigmailMsgComposeOverlay.js
+msg-compose-button-send = &Anfon Neges
+msg-compose-details-button-label = Manylion…
+msg-compose-details-button-access-key = M
+send-aborted = Ataliwyd y weithred o anfon.
+key-not-trusted = Dim digon o ymddiriedaeth ar gyfer allwedd '{ $key }'
+key-not-found = Heb ddarganfod allwedd '{ $key }'
+key-revoked = Allwedd '{ $key }' wedi'i ddirymu
+key-expired = Allwedd '{ $key }' wedi dod i ben
+msg-compose-internal-error = Digwyddodd gwall mewnol.
+keys-to-export = Dewiswch Allweddi OpenPGP i'w Mewnosod
+msg-compose-partially-encrypted-inlinePGP =
+    Roedd y neges rydych chi'n ymateb iddi yn cynnwys rhannau heb eu hamgryptio ac wedi'u hamgryptio. Os nad oedd yr anfonwr yn gallu dadgryptio rhai rhannau o'r neges yn wreiddiol, efallai eich bod yn gollwng gwybodaeth gyfrinachol nad oedd yr anfonwr yn gallu dadgryptio ei hun yn wreiddiol.
+    Ystyriwch dynnu'r holl destun a ddyfynnwyd o'ch ateb i'r anfonwr hwn.
+msg-compose-cannot-save-draft = Gwall wrth gadw drafft
+msg-compose-partially-encrypted-short = Gwyliwch rhag gollwng gwybodaeth sensitif - e-bost wedi'i amgryptio'n rhannol.
+quoted-printable-warn =
+    Rydych wedi galluogi amgodio 'dyfyniad-argraffadwy' ar gyfer anfon negeseuon. Gall hyn arwain at ddadgryptio anghywir a/neu ddilysu'ch neges.
+    Ydych chi am ddiffodd anfon negeseuon 'dyfyniad-argraffadwy' nawr?
+minimal-line-wrapping =
+    Rydych chi wedi gosod lapio llinell i nodau { $width }. Ar gyfer amgryptio a/neu lofnodi cywir, mae angen i'r gwerth hwn fod yn 68 o leiaf.
+    Ydych chi am newid amlapio llinell i 68 nod nawr?
+sending-news =
+    Ataliwyd gweithrediad anfon wedi'i amgryptio.
+    Nid oes modd amgryptio'r neges hon oherwydd bod derbynwyr grwpiau newyddion. Ail-anfonwch y neges heb amgryptio.
+send-to-news-warning =
+    Rhybudd: rydych chi ar fin anfon e-bost wedi'i amgryptio i grŵp newyddion.
+    Nid yw hyn yn cael ei annog oherwydd nad yw ond yn gwneud synnwyr os yw pob aelod o'r grŵp yn gallu dadgryptio'r neges, h.y. mae angen amgryptio'r neges gydag allweddi holl gyfranogwyr y grŵp. Anfonwch y neges hon dim ond os ydych chi'n gwybod yn union beth rydych chi'n ei wneud.
+    Parhau?
+save-attachment-header = Cadw atodiad wedi'i ddadgryptio
+possibly-pgp-mime = Neges wedi'i hamgryptio neu wedi'i llofnodi gan PGP/MIME o bosibl; defnyddiwch swyddogaeth 'Dadgryptio/Gwirio' i wirio
+cannot-send-sig-because-no-own-key = Methu llofnodi'r neges hon yn ddigidol, oherwydd nid ydych eto wedi ffurfweddu amgryptio pen-i-ben ar gyfer <{ $key }>
+cannot-send-enc-because-no-own-key = Methu anfon y neges hon wedi'i hamgryptio, oherwydd nid ydych eto wedi ffurfweddu amgryptio pen-i-ben ar gyfer <{ $key }>
+
+# Strings used in decryption.jsm
+do-import-multiple =
+    Mewnforio'r allweddi canlynol?
+    { $key }
+do-import-one = Mewnforio { $name } ({ $id })?
+cant-import = Gwall wrth fewnforio allwedd gyhoeddus
+unverified-reply = Mae'n debyg bod rhan neges wedi'i mewnoli (ateb) wedi'i haddasu
+key-in-message-body = Wedi canfod allwedd yng nghorff y neges. Cliciwch 'Allwedd Mewnforio' i fewnforio'r allwedd
+sig-mismatch = Gwall - Camgydweddiad llofnod
+invalid-email = Gwall - cyfeiriad(au) e-bost annilys
+attachment-pgp-key =
+    Mae'n ymddangos bod yr atodiad '{ $name }' rydych chi'n ei agor yn ffeil allwedd OpenPGP.
+    Cliciwch 'Mewnforio' i fewnforio'r allweddi sydd wedi'u cynnwys neu 'Golwg' i weld cynnwys y ffeil mewn ffenestr porwr
+dlg-button-view = &Golwg
+
+# Strings used in enigmailMsgHdrViewOverlay.js
+decrypted-msg-with-format-error = Neges wedi'i dadgryptio (fformat e-bost PGP wedi'i dorri wedi'i adfer yn ôl pob tebyg wedi'i achosi gan hen weinydd Exchange, fel na fyddai'r canlyniad yn berffaith i'w ddarllen o bosibl)
+
+# Strings used in encryption.jsm
+not-required = Gwall - nid oes angen amgryptio
+
+# Strings used in windows.jsm
+no-photo-available = Dim Llun ar gael
+error-photo-path-not-readable = Nid yw llwybr llun '{ $photo }' yn ddarllenadwy
+debug-log-title = Cofnod Dadfygio OpenPGP
+
+# Strings used in dialog.jsm
+repeat-prefix = Bydd y rhybudd hwn yn ailadrodd { $count }
+repeat-suffix-singular = rhagor o amser.
+repeat-suffix-plural = rhagor o amser.
+no-repeat = Ni fydd y rhybudd hwn yn cael ei ddangos eto.
+dlg-keep-setting = Cofiwch fy ateb a pheidiwch â gofyn imi eto
+dlg-button-ok = &IAWN
+dlg-button-close = &Cau
+dlg-button-cancel = &Diddymu
+dlg-no-prompt = Peidio dangos y blwch deialog eto.
+enig-prompt = Anogwr OpenPGP
+enig-confirm = Cadarnhad OpenPGP
+enig-alert = Rhybudd OpenPGP
+enig-info = Manylion OpenPGP
+
+# Strings used in persistentCrypto.jsm
+dlg-button-retry = &Ceisio eto
+dlg-button-skip = &Hepgor
+
+# Strings used in enigmailMsgBox.js
+enig-alert-title =
+    .title = Rhybudd OpenPGP
diff --git a/l10n-cy/mail/messenger/otr/add-finger.ftl b/l10n-cy/mail/messenger/otr/add-finger.ftl
new file mode 100644
index 0000000000..0dac137db6
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/add-finger.ftl
@@ -0,0 +1,16 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+otr-add-finger-title = Ychwanegu bysbrint Allwedd OTR
+
+# Variables:
+#   $name (String) - name of a chat contact person
+# Do not translate 'OTR' (name of an encryption protocol)
+otr-add-finger-description = Rhowch bysbrint allwedd OTR ar gyfer { $name }.
+
+otr-add-finger-fingerprint = Bysbrint
+otr-add-finger-tooltip-error = Nod annilys wedi'i roi. Dim ond llythrennau ABCDEF a rhifau sy'n cael eu caniatáu
+
+otr-add-finger-input =
+    .placeholder = Bysbrint allwedd OTR 40 nod o hyd
diff --git a/l10n-cy/mail/messenger/otr/am-im-otr.ftl b/l10n-cy/mail/messenger/otr/am-im-otr.ftl
new file mode 100644
index 0000000000..dbd8004669
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/am-im-otr.ftl
@@ -0,0 +1,26 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+account-encryption =
+    .label = Amgryptio Pen-i-Ben
+account-otr-label = Negeseuon Dim Cofnod (OTR)
+account-otr-description2 = Mae { -brand-short-name } yn cefnogi amgryptio sgyrsiau un i un o'r dechrau i'r diwedd wedi ei seilio ar OTR. Mae hyn yn atal trydydd partïon rhag clustfeinio ar sgyrsiau. Dim ond pan fydd y person arall hefyd yn defnyddio meddalwedd sy'n cefnogi OTR y mae modd defnyddio amgryptio o'r dechrau i'r diwedd.
+otr-encryption-title = Amgryptio wedi'i Wirio
+otr-encryption-caption = Er mwyn galluogi pobl eraill i wirio'ch hunaniaeth mewn sgyrsiau OTR, rhannwch eich bysbrintiau OTR eich hun gan ddefnyddio sianel gyfathrebu allanol (tu-allan-i'r-band).
+otr-fingerprint-label = Eich Bysbrint:
+view-fingerprint-button =
+    .label = Rheoli Bysbrintiau Cysylltiadau
+    .accesskey = R
+otr-settings-title = Gosodiadau OTR
+otr-require-encryption =
+    .label = Angen amgryptio o'r dechrau i'r diwedd ar gyfer sgyrsiau un i un
+otr-require-encryption-info =
+    Wrth ofyn am amgryptio negeseuon o ben-i-ben, ni fydd negeseuon mewn sgyrsiau
+    un i un yn cael eu hanfon oni bai bod modd eu hamgryptio. Ni fydd negeseuon wedi'u
+    derbyn heb eu hamgryptio yn cael eu dangos fel rhan o'r sgwrs arferol, na'u cofnodi chwaith.
+otr-verify-nudge =
+    .label = Atgoffa bob tro i wirio cyswllt heb ei wirio
+
+otr-not-yet-available = ddim ar gael eto
+
diff --git a/l10n-cy/mail/messenger/otr/auth.ftl b/l10n-cy/mail/messenger/otr/auth.ftl
new file mode 100644
index 0000000000..da284a7bf6
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/auth.ftl
@@ -0,0 +1,60 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+otr-auth =
+    .title = Gwirio hunaniaeth cyswllt
+    .buttonlabelaccept = Gwirio
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+auth-title = Gwirio hunaniaeth { $name }
+
+# Variables:
+#   $own_name (String) - the user's own screen name
+auth-your-fp-value = Bysbrint i chi, { $own_name }:
+
+# Variables:
+#   $their_name (String) - the screen name of a chat contact
+auth-their-fp-value = Bysbrint i { $their_name }:
+
+auth-help = Mae gwirio hunaniaeth cyswllt yn helpu i sicrhau bod y sgwrs yn wirioneddol breifat, gan ei gwneud yn anodd iawn i drydydd parti glustfeinio neu drin y sgwrs.
+
+auth-help-title = Cymorth dilysu
+
+auth-question-received = Dyma'r cwestiwn sy'n cael ei ofyn gan eich cyswllt:
+
+auth-yes =
+    .label = Iawn
+
+auth-no =
+    .label = Na
+
+auth-verified = Rwyf wedi gwirio mai hwn yw'r bysprint cywir mewn gwirionedd.
+
+auth-manual-verification = Gwirio bysprintiau â llaw
+auth-question-and-answer = Cwestiwn ac ateb
+auth-shared-secret = Cyfrinach wedi'i rannu
+
+auth-manual-verification-label =
+    .label = { auth-manual-verification }
+
+auth-question-and-answer-label =
+    .label = { auth-question-and-answer }
+
+auth-shared-secret-label =
+    .label = { auth-shared-secret }
+
+auth-manual-instruction = Cysylltwch â'ch partner sgwrsio arfaethedig trwy ryw sianel ddilys arall, fel e-bost wedi'i lofnodi gan OpenPGP neu dros y ffôn. Fe ddylech ddweud wrth eich gilydd beth yw eich bysbrintiau.  (Mae bysbrintiau yn wiriad sy'n adnabod allwedd amgryptio.) Os yw'r bysprintiau yn cyfateb, dylech nodi yn y dialog isod eich bod wedi gwirio'r bysprint.
+
+auth-how = Sut hoffech chi wirio hunaniaeth eich cyswllt?
+
+auth-qa-instruction = Meddyliwch am gwestiwn y mae'r ateb yn hysbys i chi a'ch cyswllt yn unig. Rhowch y cwestiwn a'r ateb, yna arhoswch i'ch cyswllt roi'r ateb. Os nad yw'r atebion yn cydweddu, gall y sianel gyfathrebu rydych chi'n ei defnyddio fod o dan wyliadwriaeth.
+
+auth-secret-instruction = Meddyliwch am gyfrinach sy'n hysbys i chi a'ch cyswllt yn unig. Peidiwch â defnyddio'r un cysylltiad Rhyngrwyd i gyfnewid y gyfrinach. Rhowch y gyfrinach, yna arhoswch i'ch cyswllt ei roi. Os nad yw'r cyfrinachau yn cyfateb, gall y sianel gyfathrebu rydych chi'n ei defnyddio fod o dan wyliadwriaeth.
+
+auth-question = Rhowch gwestiwn:
+
+auth-answer = Rhowch yr ateb (sensitif i faint):
+
+auth-secret = Rhowch y gyfrinach:
diff --git a/l10n-cy/mail/messenger/otr/chat.ftl b/l10n-cy/mail/messenger/otr/chat.ftl
new file mode 100644
index 0000000000..8ca2af4cba
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/chat.ftl
@@ -0,0 +1,19 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+state-label = Statws Amgryptio:
+
+start-text = Cychwynnwch sgwrs wedi'i hamgryptio
+
+start-label =
+    .label = { start-text }
+
+start-tooltip =
+    .tooltiptext = { start-text }
+
+end-label =
+    .label = Gorffennwch y sgwrs wedi'i hamgryptio
+
+auth-label =
+    .label = Gwiriwch hunaniaeth eich cyswllt
diff --git a/l10n-cy/mail/messenger/otr/finger-sync.ftl b/l10n-cy/mail/messenger/otr/finger-sync.ftl
new file mode 100644
index 0000000000..2b8b76e066
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/finger-sync.ftl
@@ -0,0 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+finger-yes = Gwiriwyd
+finger-no = Heb ei wirio
+
+finger-subset-title = Tynnu Bysbrintiau
+finger-subset-message = Nid oedd modd tynnu o leiaf un bysbrint, oherwydd ar hyn o bryd mae'r allwedd gyfatebol yn cael ei defnyddio mewn sgwrs weithredol.
+
+finger-remove-all-title = Tynnu'r Holl Bysbrintiau
+finger-remove-all-message = Ydych chi'n siŵr eich bod chi am dynnu'r holl bysbrintiau a welwyd o'r blaen? Bydd yr holl wiriadau hunaniaeth OTR blaenorol yn cael eu colli.
diff --git a/l10n-cy/mail/messenger/otr/finger.ftl b/l10n-cy/mail/messenger/otr/finger.ftl
new file mode 100644
index 0000000000..fcb5974c4d
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/finger.ftl
@@ -0,0 +1,20 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+otr-finger-title = Bysbrintiau OTR a Welwyd Eisoes
+
+finger-intro = Bysprintiau allweddol OTR o sgyrsiau amgryptiedig blaenorol o'r pen-i-ben.
+
+finger-screen-name =
+    .label = Cyswllt
+finger-verified =
+    .label = Statws Gwirio
+finger-fingerprint =
+    .label = Bysbrint
+
+finger-remove =
+    .label = Tynnu'r Dewis
+
+finger-remove-all =
+    .label = Tynnu'r Cyfan
diff --git a/l10n-cy/mail/messenger/otr/otr.ftl b/l10n-cy/mail/messenger/otr/otr.ftl
new file mode 100644
index 0000000000..98477eb96a
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/otr.ftl
@@ -0,0 +1,97 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-encryption-required-part1 = Fe wnaethoch geisio anfon neges heb ei hamgryptio at { $name }. O ran polisi, nid yw negeseuon heb eu hamgryptio'n cael eu caniatáu.
+
+msgevent-encryption-required-part2 = Yn ceisio cychwyn sgwrs breifat. Bydd eich neges yn cael ei ail anfon pan fydd y sgwrs breifat yn cychwyn.
+msgevent-encryption-error = Digwyddodd gwall wrth amgryptio'ch neges. Nid yw'r neges wedi'i hanfon.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-connection-ended = Mae { $name } eisoes wedi cau eu cysylltiad wedi'i amgryptio â chi. Er mwyn osgoi eich bod yn anfon neges heb ei hamgryptio ar ddamwain, nid yw eich neges wedi ei hanfon. Gorffennwch eich sgwrs wedi'i hamgryptio, neu ail gychwynnwch hi.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-setup-error = Digwyddodd gwall wrth drefnu sgwrs breifat gyda { $name }.
+
+# Do not translate 'OTR' (name of an encryption protocol)
+msgevent-msg-reflected = Rydych yn derbyn eich negeseuon OTR eich hun. Rydych naill ai'n ceisio siarad â chi'ch hun, neu mae rhywun yn adlewyrchu'ch negeseuon yn ôl atoch chi.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-msg-resent = Cafodd y neges olaf at { $name } ei hail anfon.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-rcvdmsg-not-private = Mae'r neges amgryptiedig a dderbyniwyd gan { $name } yn annarllenadwy, gan nad ydych yn cyfathrebu'n breifat ar hyn o bryd.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-rcvdmsg-unreadable = Rydych wedi derbyn neges amgryptiedig annarllenadwy gan { $name }.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-rcvdmsg-malformed = Rydych wdi derbyn neges ddata wedi'i hanffurfio gan { $name }.
+
+# A Heartbeat is a technical message used to keep a connection alive.
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-log-heartbeat-rcvd = Curiad calon wedi'i dderbyn gan { $name }.
+
+# A Heartbeat is a technical message used to keep a connection alive.
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-log-heartbeat-sent = Curiad calon wedi'i anfon at { $name }.
+
+# Do not translate 'OTR' (name of an encryption protocol)
+msgevent-rcvdmsg-general-err = Digwyddodd gwall annisgwyl wrth geisio diogelu'ch sgwrs gan ddefnyddio OTR.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+#   $msg (string) - the message that was received.
+msgevent-rcvdmsg-unencrypted = Nid yw'r neges ganlynol a dderbyniwyd gan { $name } wedi'i hamgryptio: { $msg }
+
+# Do not translate 'OTR' (name of an encryption protocol)
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-rcvdmsg-unrecognized = Rydych wedi derbyn neges OTR heb ei hadnabod gan { $name }.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+msgevent-rcvdmsg-for-other-instance = Mae { $name } wedi anfon neges a fwriadwyd ar gyfer sesiwn wahanol. Os ydych wedi mewngofnodi sawl gwaith, efallai y bydd sesiwn arall wedi derbyn y neges.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+context-gone-secure-private = Cychwynnodd sgwrs breifat gyda { $name }.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+context-gone-secure-unverified = Cychwynnodd sgwrs breifat heb ei gwirio gyda { $name }.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+context-still-secure = Adnewyddwyd y sgwrs wedi'i hamgryptio yn llwyddiannus gyda { $name }.
+
+error-enc = Digwyddodd gwall wrth amgryptio'r neges.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+error-not-priv = Rydych wedi anfon data wedi'i amgryptio at { $name }, nad oedd yn ei ddisgwyl.
+
+error-unreadable = Rydych wedi trosglwyddo neges annarllenadwy wedi'i hamgryptio.
+error-malformed = Rydych wedi trosglwyddo neges ddata wedi'i hanffurfio.
+
+resent = [ail anfon]
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+tlv-disconnected = Mae { $name } wedi dod â'u sgwrs wedi'i hamgryptio gyda chi i ben; dylech wneud yr un peth.
+
+# Do not translate "Off-the-Record" and "OTR" which is the name of an encryption protocol
+# Make sure that this string does NOT contain any numbers, e.g. like "3".
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+query-msg = Mae { $name } wedi gofyn am sgwrs di-gofnod wedi'i hamgryptio (OTR). Fodd bynnag, nid oes gennych ategyn i gefnogi hynny. Gweler https://en.wikipedia.org/wiki/Off-the-Record_Messaging i gael mwy o wybodaeth.
diff --git a/l10n-cy/mail/messenger/otr/otrUI.ftl b/l10n-cy/mail/messenger/otr/otrUI.ftl
new file mode 100644
index 0000000000..6e6e519fb7
--- /dev/null
+++ b/l10n-cy/mail/messenger/otr/otrUI.ftl
@@ -0,0 +1,87 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+start-label = Cychwyn sgwrs wedi'i hamgryptio
+refresh-label = Adnewyddu sgwrs wedi'i hamgryptio
+auth-label = Gwirio hunaniaeth eich cyswllt
+reauth-label = Ail wirio hunaniaeth eich cyswllt
+
+auth-cancel = Diddymu
+auth-cancel-access-key = D
+
+auth-error = Digwyddodd gwall wrth wirio hunaniaeth eich cyswllt.
+auth-success = Gwirio hunaniaeth eich cyswllt wedi'i gwblhau'n llwyddiannus.
+auth-success-them = Mae eich cyswllt wedi gwirio'ch hunaniaeth yn llwyddiannus. Efallai yr hoffech chi wirio eu hunaniaeth hefyd trwy ofyn eich cwestiwn eich hun.
+auth-fail = Wedi methu gwirio hunaniaeth eich cyswllt.
+auth-waiting = Yn aros i'r cyswllt gwblhau'r gwiriad...
+
+finger-verify = Gwirio
+finger-verify-access-key = G
+
+finger-ignore = Anwybyddu
+finger-ignore-access-key = A
+
+# Do not translate 'OTR' (name of an encryption protocol)
+buddycontextmenu-label = Ychwanegu Bysbrint OTR
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+alert-start = Yn ceisio cychwyn sgwrs wedi'i hamgryptio gyda { $name }.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+alert-refresh = Yn ceisio adnewyddu'r sgwrs wedi'i hamgryptio gyda { $name }.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+alert-gone-insecure = Daeth y sgwrs wedi'i hamgryptio gyda { $name } i ben.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+finger-unseen = Nid yw hunaniaeth { $name } wedi'i wirio eto. Nid yw'n bosibl i glustfeinio'n achlysurol, ond gyda pheth ymdrech gallai rhywun fod yn gwrando. Rhwystrwch  wyliadwriaeth trwy wirio hunaniaeth y cyswllt hwn.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+finger-seen = Mae { $name } yn cysylltu â chi o gyfrifiadur heb ei adnabod. Nid yw'n bosibl clustfeinio'n achlysurol, ond gyda pheth ymdrech gall rhywun fod yn gwrando. Rhwystrwch wyliadwriaeth trwy wirio hunaniaeth y cyswllt hwn.
+
+state-not-private = Nid yw'r sgwrs gyfredol yn breifat.
+state-generic-not-private = Nid yw'r sgwrs gyfredol yn breifat.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+state-unverified = Mae'r sgwrs gyfredol wedi'i hamgryptio ond nid yn breifat, gan nad yw hunaniaeth { $name } wedi'i gwirio eto.
+
+state-generic-unverified = Mae'r sgwrs gyfredol wedi'i hamgryptio ond nid yw'n breifat, gan nad yw rhai hunaniaethau wedi'u gwirio eto.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+state-private = Mae hunaniaeth { $name } wedi'i wirio. Mae'r sgwrs gyfredol wedi'i hamgryptio ac yn breifat.
+
+state-generic-private = Mae'r sgwrs gyfredol wedi'i hamgryptio ac yn breifat.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+state-finished = Mae { $name } wedi dod â'u sgwrs wedi'i hamgryptio gyda chi i ben; dylech wneud yr un peth.
+
+state-not-private-label = Anniogel
+state-unverified-label = Heb ei wirio
+state-private-label = Preifat
+state-finished-label = Wedi gorffen
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+verify-request = Gofynnodd { $name } i gael dilysu'ch hunaniaeth.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+afterauth-private = Rydych wedi gwirio hunaniaeth { $name }.
+
+# Variables:
+#   $name (String) - the screen name of a chat contact person
+afterauth-unverified = Nid yw hunaniaeth { $name } wedi'i wirio.
+
+# Do not translate 'OTR' (name of an encryption protocol)
+# Variables:
+#   $error (String) - contains an error message that describes the cause of the failure
+otr-genkey-failed = Methodd cynhyrchu allwedd breifat OTR: { $error }
diff --git a/l10n-cy/mail/messenger/policies/aboutPolicies.ftl b/l10n-cy/mail/messenger/policies/aboutPolicies.ftl
new file mode 100644
index 0000000000..fb4f39bd49
--- /dev/null
+++ b/l10n-cy/mail/messenger/policies/aboutPolicies.ftl
@@ -0,0 +1,17 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+about-policies-title = Polisïau Menter
+
+# 'Active' is used to describe the policies that are currently active
+active-policies-tab = Gweithredol
+errors-tab = Gwallau
+documentation-tab = Dogfennaeth
+
+no-specified-policies-message = Mae'r gwasanaeth Polisïau Menter yn weithredol ond nid oes unrhyw bolisïau wedi'u galluogi.
+inactive-message = Mae'r gwasanaeth Polisïau Menter yn anweithredol.
+
+policy-name = Enw'r Polisi
+policy-value = Gwerth Polisi
+policy-errors = Gwallau Polisi
diff --git a/l10n-cy/mail/messenger/policies/policies-descriptions.ftl b/l10n-cy/mail/messenger/policies/policies-descriptions.ftl
new file mode 100644
index 0000000000..fbae5f2a5e
--- /dev/null
+++ b/l10n-cy/mail/messenger/policies/policies-descriptions.ftl
@@ -0,0 +1,159 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## The Enterprise Policies feature is aimed at system administrators
+## who want to deploy these settings across several Thunderbird installations
+## all at once. This is traditionally done through the Windows Group Policy
+## feature, but the system also supports other forms of deployment.
+## These are short descriptions for individual policies, to be displayed
+## in the documentation section in about:policies.
+
+policy-3rdparty = Gosod polisïau y gall WebExtensions gael mynediad atyn nhw trwy chrome.storage.managed.
+
+policy-AppAutoUpdate = Galluogi neu analluogi diweddariad rhaglen awtomatig.
+
+policy-AppUpdatePin = Rhwystro { -brand-short-name } rhag cael ei ddiweddaru y tu hwnt i fersiwn penodedig.
+
+policy-AppUpdateURL = Gosod URL diweddaru ap cyfaddas.
+
+policy-Authentication = Ffurfweddu dilysu integredig ar gyfer gwefannau sy'n ei gefnogi.
+
+policy-BackgroundAppUpdate2 = Galluogi neu analluogi'r diweddarydd cefndir.
+
+policy-BlockAboutAddons = Rhwystro mynediad at y Rheolwr Ychwanegion (about:addons).
+
+policy-BlockAboutConfig = Rhwystro mynediad at dudalen about:config.
+
+policy-BlockAboutProfiles = Rhwystro mynediad at dudalen about:profiles.
+
+policy-BlockAboutSupport = Rhwystro mynediad at dudalen about:support.
+
+policy-CaptivePortal = Galluogi neu analluogi cefnogaeth porth caeth.
+
+policy-CertificatesDescription = Ychwanegu dystysgrifau neu ddefnyddio dystysgrifau mewnol.
+
+policy-Cookies = Caniatáu neu rwystro gwefannau rhag gosod cwcis.
+
+policy-DisableBuiltinPDFViewer = Analluogi PDF.js, y dangosydd PDF mewnol yn { -brand-short-name }.
+
+policy-DisabledCiphers = Analluogi seifferau.
+
+policy-DefaultDownloadDirectory = Gosod y cyfeiriadur llwytho i lawr rhagosodedig.
+
+policy-DisableAppUpdate = Rhwystro { -brand-short-name } rhag diweddaru.
+
+policy-DisableDefaultClientAgent = Atal asiant y cleient rhagosodedig rhag cymryd unrhyw gamau. Dim ond yn berthnasol i Windows; nid oes gan lwyfannau eraill yr asiant.
+
+policy-DisableDeveloperTools = Rhwystro mynediad at offer datblygwr.
+
+policy-DisableFeedbackCommands = Analluogi gorchmynion anfon adborth o'r ddewislen Cymorth (Cyflwyno Adborth ac Adrodd ar Wefan Dwyllodrus).
+
+policy-DisableForgetButton = Rhwystro mynediad at y botwm Anghofio.
+
+policy-DisableFormHistory = Peidio cofio chwilio a hanes ffurflenni.
+
+policy-DisableMasterPasswordCreation = Os true, nid oes modd creu prif gyfrinair.
+
+policy-DisablePasswordReveal = Peidio gadael i gyfrineiriau gael eu datgelu mewn mewngofnodion wedi'u cadw.
+
+policy-DisableProfileImport = Analluogi'r gorchymyn dewislen i Fewnforio data o raglen arall.
+
+policy-DisableSafeMode = Analluogi'r nodwedd i ailgychwyn yn y Modd Diogel. Sylw: dim ond drwy Bolisi Grŵp Windows y mae modd analluogi'r defnydd o fysell Shift i fynd i'r Modd Diogel.
+
+policy-DisableSecurityBypass = Rhwystro'r defnyddiwr rhag osgoi rhai rhybuddion diogelwch.
+
+policy-DisableSystemAddonUpdate = Rhwystro { -brand-short-name } rhag gosod a diweddaru ychwanegion y system.
+
+policy-DisableTelemetry = Diffodd Telemetreg.
+
+policy-DisplayMenuBar = Dangos y Bar Dewislen drwy ragosodiad.
+
+policy-DNSOverHTTPS = FFurfweddu DNS dros HTTPS
+
+policy-DontCheckDefaultClient = Analluogi gwirio am gleient rhagosodedig wrth gychwyn.
+
+policy-DownloadDirectory = Gosod a chloi'r cyfeiriadur llwytho i lawr.
+
+# “lock” means that the user won’t be able to change this setting
+policy-EnableTrackingProtection = Galluogi neu analluogi Rhwystro Cynnwys ac o ddewis ei gloi.
+
+# “lock” means that the user won’t be able to change this setting
+policy-EncryptedMediaExtensions = Galluogi neu analluogi Estyniadau Cyfryngau Amgryptiedig a'i gloi o ddewis.
+
+# A “locked” extension can’t be disabled or removed by the user. This policy
+# takes 3 keys (“Install”, ”Uninstall”, ”Locked”), you can either keep them in
+# English or translate them as verbs.
+policy-Extensions = Gosod, dadosod neu gloi estyniadau. Mae'r dewis gosod yn cymryd URL neu lwybrau fel paramedrau. Mae'r dewisiadau Dadosod a Chloi yn cymryd dynodiad estyniadau.
+
+policy-ExtensionSettings = Rheoli pob agwedd ar osod estyniad.
+
+policy-ExtensionUpdate = Galluogi neu analluogi diweddariadau awtomatig estyniad.
+
+policy-Handlers = Ffurfweddu trinwyr rhaglenni rhagosodedig.
+
+policy-HardwareAcceleration = Os false, diffoddwch gyflymder y caledwedd.
+
+policy-InstallAddonsPermission = Caniatáu i wefannau penodol osod ychwanegion.
+
+policy-LegacyProfiles = Analluoga'r nodwedd gan orfodi proffil ar wahân ar gyfer pob gosodiad.
+
+## Do not translate "SameSite", it's the name of a cookie attribute.
+
+policy-LegacySameSiteCookieBehaviorEnabled = Galluogi gosodiad ymddygiad rhagosodedig y cwci SameSite blaenorol.
+
+policy-LegacySameSiteCookieBehaviorEnabledForDomainList = Dychwelyd i'r ymddygiad SameSite blaenorol ar gyfer cwcis ar wefannau penodol.
+
+##
+
+policy-LocalFileLinks = Caniatáu i wefannau penodol gysylltu â ffeiliau lleol.
+
+policy-ManualAppUpdateOnly = Caniatáu diweddariadau â llaw yn unig a pheidio â hysbysu'r defnyddiwr am ddiweddariadau.
+
+policy-NetworkPrediction = Galluogi neu analluogi rhagfynegiad rhwydwaith (DNS prefetching).
+
+policy-OfferToSaveLogins = Gorfodi'r gosodiad i ganiatáu i { -brand-short-name } gynnig cofio mewngofnodion a chyfrineiriau wedi eu cadw. Mae gwerthoedd gwir a gau'n cael eu derbyn.
+
+policy-OfferToSaveLoginsDefault = Gosod y gwerth rhagosodedig ar gyfer caniatáu i { -brand-short-name } gynnig cofio mewngofnodion a chyfrineiriau wedi'u cadw. Mae gwerthoedd gwir a ffug yn cael eu derbyn.
+
+policy-OverrideFirstRunPage = Diystyru y dudalen rhediad gyntaf. Gosod y polisi hwn i gwag os ydych am analluogi'r dudalen rhediad cyntaf.
+
+policy-OverridePostUpdatePage = Diystyru'r dudalen ôl ddiweddaru "Beth sy'n Newydd". Gosodwch y polisi hwn i gwag os hoffech chi analluogi'r dudalen ôl ddiweddaru.
+
+policy-PasswordManagerEnabled = Galluogi cadw cyfrineiriau i'r rheolwr cyfrinair.
+
+# PDF.js and PDF should not be translated
+policy-PDFjs = Analluogi neu ffurfweddu PDF.js, darllenydd PDF mewnol { -brand-short-name }.
+
+policy-Permissions2 = Ffurfweddu caniatâd ar gyfer camera, meicroffon, lleoliad, hysbysiadau ac awtochwarae.
+
+policy-Preferences = Gosod a chloi'r gwerth ar gyfer is-set o ddewisiadau.
+
+policy-PrimaryPassword = Ei gwneud yn ofynnol neu i atal defnyddio Prif Gyfrinair.
+
+policy-PromptForDownloadLocation = Gofynnwch ble i arbed ffeiliau wrth eu llwytho i lawr.
+
+policy-Proxy = Ffurfweddi gosodiadau dirprwyol.
+
+policy-RequestedLocales = Gosod y rhestr o locales gofynnol ar gyfer y rhaglen yn ôl eich trefn dewis.
+
+policy-SanitizeOnShutdown2 = Clirio data llywio wrth gau.
+
+policy-SearchEngines = Ffurfweddu gosodiadau peiriannau chwilio. Dim ond yn y fersiwn Extended Support Release (ESR) mae'r polisi hwn ar gael.
+
+policy-SearchSuggestEnabled = Galluogi neu analluogi awgrymiadau chwilio.
+
+# For more information, see https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/PKCS11/Module_Installation
+policy-SecurityDevices = Gosod modiwlau PKCS#11.
+
+policy-SSLVersionMax = Gosod y fersiwn SSL uchaf.
+
+policy-SSLVersionMin = Gosodwch y fersiwn SSL leiaf.
+
+policy-SupportMenu = Ychwanegu eitem dewislen cymorth cyfaddas i'r ddewislen gymorth.
+
+policy-UserMessaging = Peidio dangos rhai negeseuon i'r defnyddiwr.
+
+# “format” refers to the format used for the value of this policy.
+policy-WebsiteFilter = Rhwystro gwefannau rhag derbyn ymweliadau. Gw. dogfennaeth am ragor o wybodaeth ar y fformat.
diff --git a/l10n-cy/mail/messenger/preferences/am-copies.ftl b/l10n-cy/mail/messenger/preferences/am-copies.ftl
new file mode 100644
index 0000000000..46d71416d4
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/am-copies.ftl
@@ -0,0 +1,5 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+account-prefs-show-address-row-description = Gadael y maes cyfeiriad yn wag bob tro i ddangos y rhes cyfeiriad wrth gychwyn neges newydd.
diff --git a/l10n-cy/mail/messenger/preferences/am-im.ftl b/l10n-cy/mail/messenger/preferences/am-im.ftl
new file mode 100644
index 0000000000..235a87a149
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/am-im.ftl
@@ -0,0 +1,23 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+account-settings-title = Gosodiadau Dilysu
+account-channel-title = Sianeli Rhagosodedig
+
+chat-autologin =
+    .label = Mewngofnodi wrth gychwyn
+
+chat-encryption-generic = Generig
+chat-encryption-log =
+    .label = Cynnwys negeseuon wedi'u hamgryptio o'r dechrau i'r diwedd mewn cofnodion sgwrsio
+chat-encryption-label = Amgryptio Cynhenid o'r Dechrau i'r Diwedd
+chat-encryption-description = Mae { $protocol } yn darparu amgryptio o'r dechrau i'r diwedd ar gyfer negeseuon sgwrsio. Mae hyn yn atal trydydd parti rhag clustfeinio ar sgyrsiau. Efallai y bydd angen camau gosod ychwanegol isod er mwyn i'r amgryptio fod yn weithredol.
+chat-encryption-status = Statws Amgryptio
+chat-encryption-placeholder = Amgryptio heb ei gychwyn.
+chat-encryption-sessions = Sesiynau
+chat-encryption-sessions-description = Er mwyn i amgryptio o'r dechrau i'r diwedd weithio'n gywir, mae'n rhaid i chi ymddiried yn y sesiynau eraill sydd wedi mewngofnodi i'ch cyfrif ar hyn o bryd. Mae angen rhyngweithio â'r rhaglen arall i wirio sesiwn. Gallai gwirio sesiwn arwain at bob sesiwn y mae'n ymddiried ynddo hefyd i gael eu hymddiried gan { -brand-short-name }.
+chat-encryption-session-verify = gwirio
+    .title = Gwirio hunaniaeth y sesiwn yma
+chat-encryption-session-trusted = ymddiried ynddo
+    .title = Mae hunaniaeth y sesiwn wedi'i wirio
diff --git a/l10n-cy/mail/messenger/preferences/application-manager.ftl b/l10n-cy/mail/messenger/preferences/application-manager.ftl
new file mode 100644
index 0000000000..878d6738b2
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/application-manager.ftl
@@ -0,0 +1,12 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+app-manager-window-dialog =
+    .title = Manylion Rhaglen
+    .style = width: 30em; min-height: 20em;
+app-manager-window-dialog2 =
+    .title = Manylion Rhaglen
+remove-app-button =
+    .label = Tynnu
+    .accesskey = T
diff --git a/l10n-cy/mail/messenger/preferences/attachment-reminder.ftl b/l10n-cy/mail/messenger/preferences/attachment-reminder.ftl
new file mode 100644
index 0000000000..ebb3e64efd
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/attachment-reminder.ftl
@@ -0,0 +1,26 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+attachment-reminder-window =
+    .title = Allweddair Atgoffa am Atodiad
+
+attachment-reminder-label = Bydd { -brand-short-name } yn eich rhybuddio am atodiadau coll os ydych ar fin anfon e-bost yn cynnwys un o'r allweddeiriau hyn.
+
+keyword-new-button =
+    .label = Newydd…
+    .accesskey = N
+
+keyword-edit-button =
+    .label = Golygu…
+    .accesskey = G
+
+keyword-remove-button =
+    .label = Dileu
+    .accesskey = D
+
+new-keyword-title = Allweddair Newydd
+new-keyword-label = Allweddair:
+
+edit-keyword-title = Golygu Allweddair
+edit-keyword-label = Allweddair:
diff --git a/l10n-cy/mail/messenger/preferences/colors.ftl b/l10n-cy/mail/messenger/preferences/colors.ftl
new file mode 100644
index 0000000000..14d4c00561
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/colors.ftl
@@ -0,0 +1,42 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+colors-dialog-window =
+    .title = Lliwiau
+    .style =
+        { PLATFORM() ->
+            [macos] width: 41em !important
+           *[other] width: 38em !important
+        }
+colors-dialog-window2 =
+    .title = Lliwiau
+colors-dialog-legend = Testun a Chefndir
+text-color-label =
+    .value = Testun:
+    .accesskey = T
+background-color-label =
+    .value = Cefndir:
+    .accesskey = C
+use-system-colors =
+    .label = Defnyddio lliwiau'r system
+    .accesskey = s
+colors-link-legend = Lliw Dolenni
+link-color-label =
+    .value = Dolenni heb gael Ymweliad:
+    .accesskey = D
+visited-link-color-label =
+    .value = Dolenni wedi cael Ymweliad:
+    .accesskey = w
+underline-link-checkbox =
+    .label = Tanlinellu dolenni
+    .accesskey = d
+override-color-label =
+    .value = Anwybyddu'r lliwiau pennwyd gan y cynnwys gyda fy newis uchod:
+    .accesskey = A
+override-color-always =
+    .label = Bob tro
+override-color-auto =
+    .label = Dim ond gyda themâu Cyferbyniad Uchel
+override-color-never =
+    .label = Byth
diff --git a/l10n-cy/mail/messenger/preferences/connection.ftl b/l10n-cy/mail/messenger/preferences/connection.ftl
new file mode 100644
index 0000000000..a69ece8827
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/connection.ftl
@@ -0,0 +1,94 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+connection-dns-over-https-url-resolver = Defnyddio Darparwr
+    .accesskey = D
+# Variables:
+#   $name (String) - Display name or URL for the DNS over HTTPS provider
+connection-dns-over-https-url-item-default =
+    .label = { $name } (Rhagosodiad)
+    .tooltiptext = Defnyddiwch yr URL rhagosodedig ar gyfer datrys DNS dros HTTPS
+connection-dns-over-https-url-custom =
+    .label = Cyfaddas
+    .accesskey = C
+    .tooltiptext = Rhowch eich hoff URL er mwyn datrys DNS drod HTTPS
+connection-dns-over-https-custom-label = Cyfaddas
+connection-dialog-window =
+    .title = Gosodiadau Cysylltu
+    .style =
+        { PLATFORM() ->
+            [macos] width: 44em !important
+           *[other] width: 49em !important
+        }
+connection-dialog-window2 =
+    .title = Gosodiadau Cysylltu
+disable-extension-button = Analluogi Estyniad
+# Variables:
+#   $name (String) - The extension that is controlling the proxy settings.
+#
+# The extension-icon is the extension's icon, or a fallback image. It should be
+# purely decoration for the actual extension name, with alt="".
+proxy-settings-controlled-by-extension = Mae estyniad, <img data-l10n-name="icon"/> { $name }, yn rheoli sut mae { -brand-short-name } yn cysylltu â'r Rhyngrwyd.
+connection-proxy-legend = Ffurfweddu'r Dirprwyon i Gael Mynediad i'r Rhyngrwyd
+proxy-type-no =
+    .label = Dim dirprwy
+    .accesskey = D
+proxy-type-wpad =
+    .label = Awtoganfod gosodiadau dirprwyol ar gyfer y rhwydwaith
+    .accesskey = w
+proxy-type-system =
+    .label = Defnyddio gosodiadau dirprwyol y system
+    .accesskey = e
+proxy-type-manual =
+    .label = Ffurfweddiad dirprwy gyda llaw:
+    .accesskey = F
+proxy-http-label =
+    .value = Dirprwy yr HTTP:
+    .accesskey = H
+http-port-label =
+    .value = Porth:
+    .accesskey = P
+proxy-http-sharing =
+    .label = Defnyddiwch y dirprwy yma hefyd ar gyfer HTTPS
+    .accesskey = x
+proxy-https-label =
+    .value = Dirprwy HTTPS:
+    .accesskey = S
+ssl-port-label =
+    .value = Porth:
+    .accesskey = o
+proxy-socks-label =
+    .value = Gwesteiwr SOCKS:
+    .accesskey = C
+socks-port-label =
+    .value = Porth:
+    .accesskey = t
+proxy-socks4-label =
+    .label = SOCKS v4
+    .accesskey = K
+proxy-socks5-label =
+    .label = SOCKS v5
+    .accesskey = v
+proxy-type-auto =
+    .label = URL ffurfweddu dirprwy yn awtomatig:
+    .accesskey = U
+proxy-reload-label =
+    .label = Ail-lwytho
+    .accesskey = l
+no-proxy-label =
+    .value = Dim Dirprwy ar gyfer:
+    .accesskey = m
+no-proxy-example = Esiampl: .mozilla.org, .net.nz, 192.168.1.0/24
+# Do not translate "localhost", "127.0.0.1/8" and "::1". (You can translate "and".)
+connection-proxy-noproxy-localhost-desc-2 = Nid yw cysylltiadau â localhost, 127.0.0.1/8, a ::1 byth yn cael eu dirprwyo.
+proxy-password-prompt =
+    .label = Peidio gofyn am ddilysiad os yw'r cyfrinair wedi ei gadw
+    .accesskey = d
+    .tooltiptext = Mae'r dewis hwn yn eich dilysu'n dawel i ddirprwyon rydych wedi eu cadw eu manylion ar eu cyfer. Byddwn yn gofyn os bydd y dilysiad yn methu.
+proxy-remote-dns =
+    .label = DNS dirprwyol pan y defnyddio SOCKS v5
+    .accesskey = D
+proxy-enable-doh =
+    .label = Galluogi DNS dros HTTPS
+    .accesskey = G
diff --git a/l10n-cy/mail/messenger/preferences/cookies.ftl b/l10n-cy/mail/messenger/preferences/cookies.ftl
new file mode 100644
index 0000000000..e509f3b61b
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/cookies.ftl
@@ -0,0 +1,46 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+cookies-window-dialog =
+    .title = Cwcis
+    .style = width: 36em;
+cookies-window-dialog2 =
+    .title = Cwcis
+window-close-key =
+    .key = w
+window-focus-search-key =
+    .key = f
+window-focus-search-alt-key =
+    .key = k
+filter-search-label =
+    .value = Chwilio:
+    .accesskey = h
+cookies-on-system-label = Mae'r cwcis canlynol wedi'u cadw ar eich cyfrifiadur:
+treecol-site-header =
+    .label = Gwefan
+treecol-name-header =
+    .label = Enw'r Cwci
+props-name-label =
+    .value = Enw:
+props-value-label =
+    .value = Cynnwys:
+props-domain-label =
+    .value = Gwesteiwr:
+props-path-label =
+    .value = Llwybr:
+props-secure-label =
+    .value = Anfon am:
+props-expires-label =
+    .value = Daw i ben:
+props-container-label =
+    .value = Cynhwysydd:
+remove-cookie-button =
+    .label = Tynnu Cwci
+    .accesskey = T
+remove-all-cookies-button =
+    .label = Tynnu Pob Cwci
+    .accesskey = P
+cookie-close-button =
+    .label = Cau
+    .accesskey = u
diff --git a/l10n-cy/mail/messenger/preferences/dock-options.ftl b/l10n-cy/mail/messenger/preferences/dock-options.ftl
new file mode 100644
index 0000000000..b7d599e5f6
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/dock-options.ftl
@@ -0,0 +1,25 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+dock-options-window-dialog =
+    .title = Dewisiadau eicon yr ap
+    .style = width: 35em;
+dock-options-window-dialog2 =
+    .title = Dewisiadau eicon yr ap
+dock-options-show-badge =
+    .label = Dangos eicon bathodyn
+    .accesskey = e
+bounce-system-dock-icon =
+    .label = Bywiogi eicon yr ap pan fydd neges newydd yn cyrraedd
+    .accesskey = B
+dock-icon-legend = Bathodyn eicon ap
+dock-icon-show-label =
+    .value = Bathodyn eicon ap gyda:
+count-unread-messages-radio =
+    .label = Cyfrif y negeseuon heb eu darllen
+    .accesskey = y
+count-new-messages-radio =
+    .label = Cyfrif y negeseuon newydd
+    .accesskey = y
+notification-settings-info2 = Gallwch analluogi'r bathodyn ym mhaen Hysbysiadau'r Dewisiadau System.
diff --git a/l10n-cy/mail/messenger/preferences/fonts.ftl b/l10n-cy/mail/messenger/preferences/fonts.ftl
new file mode 100644
index 0000000000..24ee309784
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/fonts.ftl
@@ -0,0 +1,151 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+fonts-window-close =
+    .key = w
+
+# Variables:
+#   $name {string, "Arial"} - Name of the default font
+fonts-label-default =
+    .label = Rhagosodiad ({ $name })
+fonts-label-default-unnamed =
+    .label = Rhagosodiad
+
+fonts-encoding-dialog-title =
+    .title = Ffontiau ac Amgodio
+
+fonts-language-legend =
+    .value = Ffontiau ar gyfer:
+    .accesskey = F
+
+fonts-proportional-label =
+    .value = Cyfrannol:
+    .accesskey = y
+
+## Languages
+
+# Note: Translate "Latin" as the name of Latin (Roman) script, not as the name of the Latin language.
+font-language-group-latin =
+    .label = Lladin
+font-language-group-japanese =
+    .label = Siapanëeg
+font-language-group-trad-chinese =
+    .label = Tsieinëeg Traddodiadol (Taiwan)
+font-language-group-simpl-chinese =
+    .label = Tsieinëeg Syml
+font-language-group-trad-chinese-hk =
+    .label = Tsieinëeg Traddodiadol (Hong Kong)
+font-language-group-korean =
+    .label = Corëeg
+font-language-group-cyrillic =
+    .label = Cyrilig
+font-language-group-el =
+    .label = Groeg
+font-language-group-other =
+    .label = Systemau Ysgrifennu Eraill
+font-language-group-thai =
+    .label = Thai
+font-language-group-hebrew =
+    .label = Hebraeg
+font-language-group-arabic =
+    .label = Arabeg
+font-language-group-devanagari =
+    .label = Devanagari
+font-language-group-tamil =
+    .label = Tamil
+font-language-group-armenian =
+    .label = Armeneg
+font-language-group-bengali =
+    .label = Bengali
+font-language-group-canadian =
+    .label = Sillafiad Unedig Canada
+font-language-group-ethiopic =
+    .label = Ethiopeg
+font-language-group-georgian =
+    .label = Georgeg
+font-language-group-gujarati =
+    .label = Gujarati
+font-language-group-gurmukhi =
+    .label = Gurmukhi
+font-language-group-khmer =
+    .label = Khmer
+font-language-group-malayalam =
+    .label = Malayalam
+font-language-group-math =
+    .label = Mathemateg
+font-language-group-odia =
+    .label = Odia
+font-language-group-telugu =
+    .label = Telugu
+font-language-group-kannada =
+    .label = Kannada
+font-language-group-sinhala =
+    .label = Sinhala
+font-language-group-tibetan =
+    .label = Tibeteg
+
+## Default font type
+
+default-font-serif =
+    .label = Serif
+
+default-font-sans-serif =
+    .label = Sans Serif
+
+font-size-proportional-label =
+    .value = Maint:
+    .accesskey = M
+
+font-size-monospace-label =
+    .value = Maint:
+    .accesskey = i
+
+font-serif-label =
+    .value = Serif:
+    .accesskey = S
+
+font-sans-serif-label =
+    .value = Sans-serif:
+    .accesskey = n
+
+font-monospace-label =
+    .value = Monospace:
+    .accesskey = M
+
+font-min-size-label =
+    .value = Lleiafswm maint ffont:
+    .accesskey = L
+
+min-size-none =
+    .label = Dim
+
+## Fonts in message
+
+font-control-legend = Rheoli Ffontiau
+
+use-document-fonts-checkbox =
+    .label = Caniatáu i negeseuon ddefnyddio ffontiau eraill
+    .accesskey = C
+
+use-fixed-width-plain-checkbox =
+    .label = Defnyddio ffont lled sefydlog ar gyfer negeseuon testun plaen
+    .accesskey = x
+
+## Language settings
+
+text-encoding-legend = Amgodiad Testun
+
+text-encoding-description = Gosod yr amgodiad testun rhagosodedig ar gyfer anfon a derbyn e-bost
+
+font-outgoing-email-label =
+    .value = Anfon E-bost:
+    .accesskey = A
+
+font-incoming-email-label =
+    .value = Derbyn E-bost:
+    .accesskey = D
+
+default-font-reply-checkbox =
+    .label = Pan yn bosib, defnyddio'r amgodiad testun rhagosodedig wrth ateb
+    .accesskey = a
diff --git a/l10n-cy/mail/messenger/preferences/languages.ftl b/l10n-cy/mail/messenger/preferences/languages.ftl
new file mode 100644
index 0000000000..c175349f74
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/languages.ftl
@@ -0,0 +1,35 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+languages-customize-moveup =
+    .label = Symud i Fyny
+    .accesskey = F
+languages-customize-movedown =
+    .label = Symud i Lawr
+    .accesskey = L
+languages-customize-remove =
+    .label = Tynnu
+    .accesskey = T
+languages-customize-select-language =
+    .placeholder = Dewis iaith i'w hychwanegu…
+languages-customize-add =
+    .label = Ychwanegu
+    .accesskey = Y
+messenger-languages-window =
+    .title = Gosodiadau Iaith { -brand-short-name }
+    .style = width: 40em
+messenger-languages-window2 =
+    .title = Gosodiadau Iaith { -brand-short-name }
+messenger-languages-description = Bydd { -brand-short-name } yn dangos yr iaith gyntaf fel eich rhagosodedig a bydd yn danogs ieithoedd eraill yn y drefn fyddan nhw'n ymddangos.
+messenger-languages-search = Chwilio am ragor o ieithoedd…
+messenger-languages-searching =
+    .label = Chwilio am ieithoedd…
+messenger-languages-downloading =
+    .label = Llwytho i lawr…
+messenger-languages-select-language =
+    .label = Dewis iaith i'w hychwanegu…
+    .placeholder = Dewis iaith i'w hychwanegu…
+messenger-languages-installed-label = Ieithoedd wedi'u gosod
+messenger-languages-available-label = Ieithoedd ar gael
+messenger-languages-error = Nid yw { -brand-short-name } yn gallu diweddaru eich iaith ar hyn o bryd. Edrychwch i weld os ydych wedi'ch cysylltu i'r rhyngrwyd neu ceisiwch eto.
diff --git a/l10n-cy/mail/messenger/preferences/new-tag.ftl b/l10n-cy/mail/messenger/preferences/new-tag.ftl
new file mode 100644
index 0000000000..0791bf81a5
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/new-tag.ftl
@@ -0,0 +1,14 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+tag-dialog-window =
+    .title = Tab Newydd
+
+tag-name-label =
+    .value = Enw Tag:
+    .accesskey = T
+
+tag-color-label =
+    .value = Lliw:
+    .accesskey = L
diff --git a/l10n-cy/mail/messenger/preferences/notifications.ftl b/l10n-cy/mail/messenger/preferences/notifications.ftl
new file mode 100644
index 0000000000..e2a52d3cda
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/notifications.ftl
@@ -0,0 +1,33 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+notifications-dialog-window =
+    .title = Cyfaddasu Rhybudd E-bost Newydd
+
+customize-alert-description = Dewis pa faes i'w ddangos yn yr hysbysiad rhybudd:
+
+preview-text-checkbox =
+    .label = Testun Rhagolwg Neges
+    .accesskey = R
+
+subject-checkbox =
+    .label = Pwnc
+    .accesskey = P
+
+sender-checkbox =
+    .label = Anfonwr
+    .accesskey = A
+
+## Note: open-time-label-before is displayed first, then there's a field where
+## the user can enter a number, and open-time-label-after is displayed at the end
+## of the line. The translations of the open-time-label-before and open-time-label-after
+## parts don't have to mean the exact same thing as in English; please try instead
+## to translate the whole sentence.
+
+open-time-label-before =
+    .value = Dangos Rhybudd E-bost Newydd pob
+    .accesskey = N
+
+open-time-label-after =
+    .value = eiliad
diff --git a/l10n-cy/mail/messenger/preferences/offline.ftl b/l10n-cy/mail/messenger/preferences/offline.ftl
new file mode 100644
index 0000000000..e9cb163e47
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/offline.ftl
@@ -0,0 +1,56 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+offline-dialog-window =
+    .title = Gosodiadau All-lein
+
+autodetect-online-label =
+    .label = Dilyn y cyflwr ar-lein canfuwyd, yn awtomatig
+    .accesskey = c
+
+offline-preference-startup-label = Cyflwr â llaw wrth gychwyn:
+
+status-radio-remember =
+    .label = Cofio'r cyflwr ar-lein diwethaf
+    .accesskey = o
+
+status-radio-ask =
+    .label = Gofyn i mi am y cyflwr ar-lein
+    .accesskey = G
+
+status-radio-always-online =
+    .label = Ar-lein
+    .accesskey = r
+
+status-radio-always-offline =
+    .label = All-lein
+    .accesskey = l
+
+going-online-label = Anfon negeseuon sydd heb eu hanfon wrth fynd ar-lein?
+
+going-online-auto =
+    .label = Iawn
+    .accesskey = I
+
+going-online-not =
+    .label = Na
+    .accesskey = N
+
+going-online-ask =
+    .label = Gofyn i mi
+    .accesskey = G
+
+going-offline-label = Llwytho negeseuon i lawr ar gyfer defnydd all-lein wrth fynd all-lein?
+
+going-offline-auto =
+    .label = Iawn
+    .accesskey = w
+
+going-offline-not =
+    .label = Na
+    .accesskey = a
+
+going-offline-ask =
+    .label = Gofyn i mi
+    .accesskey = f
diff --git a/l10n-cy/mail/messenger/preferences/passwordManager.ftl b/l10n-cy/mail/messenger/preferences/passwordManager.ftl
new file mode 100644
index 0000000000..cb68e1fa76
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/passwordManager.ftl
@@ -0,0 +1,86 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+saved-logins =
+    .title = Mewngofnodion wedi eu Cadw
+window-close =
+    .key = c
+focus-search-primary-shortcut =
+    .key = c
+focus-search-alt-shortcut =
+    .key = c
+copy-provider-url-cmd =
+    .label = Copïo'r URL
+    .accesskey = U
+copy-username-cmd =
+    .label = Copïo Enw Defnyddiwr
+    .accesskey = E
+edit-username-cmd =
+    .label = Golygu Enw Defnyddiwr
+    .accesskey = G
+copy-password-cmd =
+    .label = Copïo'r Cyfrinair
+    .accesskey = o
+edit-password-cmd =
+    .label = Golygu'r Cyfrinair
+    .accesskey = G
+search-filter =
+    .accesskey = C
+    .placeholder = Chwilio
+column-heading-provider =
+    .label = Darparwr
+column-heading-username =
+    .label = Enw Defnyddiwr
+column-heading-password =
+    .label = Cyfrinair
+column-heading-time-created =
+    .label = Defnyddiwyd Gyntaf
+column-heading-time-last-used =
+    .label = Defnyddiwyd Diwethaf
+column-heading-time-password-changed =
+    .label = Newidiwyd Diwethaf
+column-heading-times-used =
+    .label = Nifer o Weithiau Defnyddiwyd
+remove =
+    .label = Tynnu
+    .accesskey = T
+import =
+    .label = Mewnforio…
+    .accesskey = M
+
+password-close-button =
+    .label = Cau
+    .accesskey = C
+
+show-passwords =
+    .label = Dangos Cyfrineiriau
+    .accesskey = D
+hide-passwords =
+    .label = Cuddio Cyfrineiriau
+    .accesskey = d
+logins-description-all = Mae mewngofnodion ar gyfer y darparwyr canlynol yn cael eu storio ar eich cyfrifiadur
+logins-description-filtered = Mae'r mewngofnodi canlynol yn cyd-fynd â'ch chwilio:
+remove-all =
+    .label = Tynnu Popeth
+    .accesskey = P
+remove-all-shown =
+    .label = Tynnu Popeth Dangoswyd
+    .accesskey = D
+remove-all-passwords-prompt = Ydych chi'n siŵr eich bod am dynnu pob cyfrinair?
+remove-all-passwords-title = Tynnu pob cyfrinair
+no-master-password-prompt = Ydych chi'n siŵr eich bod am ddangos eich cyfrineiriau?
+
+## OS Authentication dialog
+
+# This message can be seen by trying to show or copy the passwords.
+password-os-auth-dialog-message = Gwiriwch eich hunaniaeth i ddatgelu'r cyfrineiriau sydd wedi'u cadw.
+
+# This message can be seen by trying to show or copy the passwords.
+# The macOS strings are preceded by the operating system with "Thunderbird is trying to "
+# and includes subtitle of "Enter password for the user "xxx" to allow this." These
+# notes are only valid for English. Please test in your locale.
+password-os-auth-dialog-message-macosx = datgelu'r cyfrineiriau sydd wedi'u cadw
+
+# Don't change this label.
+password-os-auth-dialog-caption = { -brand-full-name }
diff --git a/l10n-cy/mail/messenger/preferences/permissions.ftl b/l10n-cy/mail/messenger/preferences/permissions.ftl
new file mode 100644
index 0000000000..6307a7850e
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/permissions.ftl
@@ -0,0 +1,45 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+permissions-reminder-window =
+    .title = Eithriadau
+    .style = width: 45em;
+permissions-reminder-window2 =
+    .title = Eithriadau
+permission-preferences-close-window =
+    .key = f
+website-address-label =
+    .value = Cyfeiriad y wefan:
+    .accesskey = w
+block-button =
+    .label = Rhwystro
+    .accesskey = R
+allow-session-button =
+    .label = Caniatáu ar gyfer y Sesiwn
+    .accesskey = S
+allow-button =
+    .label = Caniatáu
+    .accesskey = a
+treehead-sitename-label =
+    .label = Gwefan
+treehead-status-label =
+    .label = Statws
+remove-site-button =
+    .label = Tynnu'r Wefan
+    .accesskey = T
+remove-all-site-button =
+    .label = Tynnu Pob Gwefan
+    .accesskey = P
+cancel-button =
+    .label = Diddymu
+    .accesskey = D
+save-button =
+    .label = Cadw Newidiadau
+    .accesskey = N
+permission-can-label = Caniatáu
+permission-can-access-first-party-label = Caniatáu'r parti cyntaf yn unig
+permission-can-session-label = Caniatáu ar gyfer y Sesiwn
+permission-cannot-label = Rhwystro
+invalid-uri-message = Rhowch gyfeiriad e-bost dilys
+invalid-uri-title = Rhoddwyd Enw Parth Annilys
diff --git a/l10n-cy/mail/messenger/preferences/preferences.ftl b/l10n-cy/mail/messenger/preferences/preferences.ftl
new file mode 100644
index 0000000000..8da74cf4c3
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/preferences.ftl
@@ -0,0 +1,932 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+close-button =
+    .aria-label = Cau
+
+preferences-doc-title2 = Gosodiadau
+
+category-list =
+    .aria-label = Categorïau
+
+pane-general-title = Cyffredinol
+category-general =
+    .tooltiptext = { pane-general-title }
+
+pane-compose-title = Ysgrifennu
+category-compose =
+    .tooltiptext = Ysgrifennu
+
+pane-privacy-title = Preifatrwydd a Diogelwch
+category-privacy =
+    .tooltiptext = Preifatrwydd a Diogelwch
+
+pane-chat-title = Sgwrsio
+category-chat =
+    .tooltiptext = Sgwrsio
+
+pane-calendar-title = Calendr
+category-calendar =
+    .tooltiptext = Calendr
+
+general-language-and-appearance-header = Iaith a Gwedd
+
+general-incoming-mail-header = Derbyn E-byst
+
+general-files-and-attachment-header = Ffeiliau ac Atodiadau
+
+general-tags-header = Tagiau
+
+general-reading-and-display-header = Darllen a Dangos
+
+general-updates-header = Diweddariadau
+
+general-network-and-diskspace-header = Rhwydwaith a Lle ar Ddisg
+
+general-indexing-label = Mynegeio
+
+composition-category-header = Ysgrifennu
+
+composition-attachments-header = Atodiadau
+
+composition-spelling-title = Sillafu
+
+compose-html-style-title = Arddull HTML
+
+composition-addressing-header = Cyfeirio
+
+privacy-main-header = Preifatrwydd
+
+privacy-passwords-header = Cyfrineiriau
+
+privacy-junk-header = Sbam
+
+collection-header = Casglu a Defnyddio Data { -brand-short-name }
+
+collection-description = Rydym yn ceisio darparu dewisiadau i chi a chasglu dim ond beth sydd ei angen arnom i ddarparu a gwella { -brand-short-name } ar gyfer pawb. Rydym yn gofyn caniatâd bob tro cyn derbyn manylion personol.
+collection-privacy-notice = Hysbysiad Preifatrwydd
+
+collection-health-report-telemetry-disabled = Nid ydych bellach yn caniatáu i { -vendor-short-name } ddal data technegol a rhyngweithiol. Bydd holl ddata'r gorffennol yn cael ei ddileu cyn pen 30 diwrnod.
+collection-health-report-telemetry-disabled-link = Dysgu rhagor
+
+collection-health-report =
+    .label = Caniatáu i { -brand-short-name } anfon data technegol a rhyngweithio i { -vendor-short-name }
+    .accesskey = C
+collection-health-report-link = Dysgu rhagor
+
+# This message is displayed above disabled data sharing options in developer builds
+# or builds with no Telemetry support available.
+collection-health-report-disabled = Mae adrodd ar ddata wedi ei analluogi ar gyfer ffurfweddiad yr adeiledd hwn
+
+collection-backlogged-crash-reports =
+    .label = Caniatáu i { -brand-short-name } i anfon adroddiadau chwalu wedi eu cadw ar eich rhan
+    .accesskey = f
+collection-backlogged-crash-reports-link = Dysgu rhagor
+
+privacy-security-header = Diogelwch
+
+privacy-scam-detection-title = Canfod Twyll
+
+privacy-anti-virus-title = Gwrth Firws
+
+privacy-certificates-title = Tystysgrifau
+
+chat-pane-header = Sgwrsio
+
+chat-status-title = Statws
+
+chat-notifications-title = Hysbysiadau
+
+chat-pane-styling-header = Steilio
+
+choose-messenger-language-description = Dewis yr ieithoedd sy'n cael ei defnyddio i ddangos dewislenni, negeseuon, a hysbysiadau gan { -brand-short-name }
+manage-messenger-languages-button =
+    .label = Gosod Rhai Eraill...
+    .accesskey = G
+confirm-messenger-language-change-description = Ailgychwyn { -brand-short-name } i osod y newidiadau hyn
+confirm-messenger-language-change-button = Gosod ac Ailgychwyn
+
+update-setting-write-failure-title = Gwall wrth gadw dewisiadau Diweddaru
+
+# Variables:
+#   $path (String) - Path to the configuration file
+# The newlines between the main text and the line containing the path is
+# intentional so the path is easier to identify.
+update-setting-write-failure-message =
+    Bu gwall ar { -brand-short-name } ac nid yw wedi cadw'r newid hwn. Noder bod gosod caniatâd ar gyfer y diweddariad hwn yn gofyn am ganiatâd i ysgrifennu at y ffeil isod. Efallai y byddwch chi neu weinyddwr system yn gallu datrys y gwall trwy roi rheolaeth lawn i'r ffeil hon i'r grŵp Defnyddwyr.
+    
+    Doedd dim modd ysgrifennu i ffeil: { $path }
+
+update-in-progress-title = Diweddariad ar y Gweill
+
+update-in-progress-message = Ydych chi eisiau i { -brand-short-name } barhau gyda'r diweddariad hwn?
+
+update-in-progress-ok-button = &Dileu
+# Continue is the cancel button so pressing escape or using a platform standard
+# method of closing the UI will not discard the update.
+update-in-progress-cancel-button = &Parhau
+
+account-button = Gosodiadau'r Cyfrif
+open-addons-sidebar-button = Ychwanegion a Themâu
+
+## OS Authentication dialog
+
+# This message can be seen by trying to add a Primary Password.
+primary-password-os-auth-dialog-message-win = I greu Prif Gyfrinair, nodwch fanylion eich mewngofnodi Windows. Mae hyn yn helpu i ddiogelu eich cyfrifon.
+
+# This message can be seen by trying to add a Primary Password.
+# The macOS strings are preceded by the operating system with "Thunderbird is trying to "
+# and includes subtitle of "Enter password for the user "xxx" to allow this." These
+# notes are only valid for English. Please test in your locale.
+primary-password-os-auth-dialog-message-macosx = creu Prif Gyfrinair
+
+# Don't change this label.
+master-password-os-auth-dialog-caption = { -brand-full-name }
+
+## General Tab
+
+focus-search-shortcut =
+    .key = f
+focus-search-shortcut-alt =
+    .key = k
+
+general-legend = Tudalen Cychwyn { -brand-short-name }
+
+start-page-label =
+    .label = Pan fydd { -brand-short-name } yn cychwyn, dangos y Dudalen Cychwyn yn y maes neges
+    .accesskey = P
+
+location-label =
+    .value = Lleoliad:
+    .accesskey = o
+restore-default-label =
+    .label = Adfer y Rhagosodiad
+    .accesskey = R
+
+default-search-engine = Peiriant Chwilio Rhagosodedig
+add-web-search-engine =
+    .label = Ychwanegu…
+    .accesskey = Y
+remove-search-engine =
+    .label = Tynnu
+    .accesskey = T
+
+add-opensearch-provider-title = Ychwanegu Darparwr OpenSearch
+add-opensearch-provider-text = Rhowch URL y darparwr OpenSearch i'w ychwanegu. Naill ai defnyddiwch URL uniongyrchol y ffeil OpenSearch Description, neu URL lle mae modd ei ddarganfod yn awtomatig.
+
+adding-opensearch-provider-failed-title = Methodd Ychwanegu Darparwr OpenSearch
+adding-opensearch-provider-failed-text = Nid oedd modd ychwanegu OpenSearch Provider ar gyfer { $url }.
+
+minimize-to-tray-label =
+    .label = Pan fydd { -brand-short-name } wedi ei leihau, ei symud i'r dror
+    .accesskey = l
+
+new-message-arrival = Pan fydd neges newydd yn cyrraedd:
+mail-play-sound-label =
+    .label =
+        { PLATFORM() ->
+            [macos] Chwarae'r ffeil sain ganlynol:
+           *[other] Canu nodyn
+        }
+    .accesskey =
+        { PLATFORM() ->
+            [macos] s
+           *[other] d
+        }
+mail-play-button =
+    .label = Chwarae
+    .accesskey = h
+
+change-dock-icon = Newid dewisiadau eicon yr ap
+app-icon-options =
+    .label = Dewisiadau Eicon Ap…
+    .accesskey = E
+
+notification-settings2 = Mae modd analluogi rhybuddion a'r sain rhagosodedig ar baen Hysbysu'r Dewisiadau System.
+
+animated-alert-label =
+    .label = Dangos rhybudd
+    .accesskey = D
+customize-alert-label =
+    .label = Cyfaddasu…
+    .accesskey = C
+
+biff-use-system-alert =
+    .label = Defnyddio hysbysiadau'r system
+
+tray-icon-unread-label =
+    .label = Dangos eicon hambwrdd ar gyfer negeseuon heb eu darllen
+    .accesskey = h
+
+tray-icon-unread-description = Argymhellir wrth ddefnyddio botymau bar tasgau bach
+
+mail-system-sound-label =
+    .label = Sain rhagosodedig y system ar gyfer e-bost newydd
+    .accesskey = S
+mail-custom-sound-label =
+    .label = Defnyddio'r ffeil sain ganlynol
+    .accesskey = D
+mail-browse-sound-button =
+    .label = Pori…
+    .accesskey = P
+
+enable-gloda-search-label =
+    .label = Galluogi Chwilio a Mynegeio Eang
+    .accesskey = G
+
+datetime-formatting-legend = Fformatio Dyddiad ac Amser
+language-selector-legend = Iaith
+
+allow-hw-accel =
+    .label = Defnyddio cyflymu caledwedd pan fydd ar gael
+    .accesskey = y
+
+store-type-label =
+    .value = Math o Storio Negeseuon ar gyfer cyfrifon newydd:
+    .accesskey = M
+
+mbox-store-label =
+    .label = Ffeil i'r ffolder (mbox)
+maildir-store-label =
+    .label = Ffeil y neges (maildir)
+
+scrolling-legend = Sgrolio
+autoscroll-label =
+    .label = Defnyddio awto sgrolio
+    .accesskey = a
+smooth-scrolling-label =
+    .label = Defnyddio sgrolio llyfn
+    .accesskey = l
+browsing-gtk-use-non-overlay-scrollbars =
+    .label = Dango bariau sgrolio bob tro
+    .accesskey = D
+
+system-integration-legend = Integreiddio System
+always-check-default =
+    .label = Gwirio bob tro os { -brand-short-name } yw'r rhaglen e-bost rhagosodedig wrth gychwyn
+    .accesskey = G
+check-default-button =
+    .label = Gwiriwch Nawr…
+    .accesskey = N
+
+# Note: This is the search engine name for all the different platforms.
+# Platforms that don't support it should be left blank.
+search-engine-name =
+    { PLATFORM() ->
+        [macos] Sbotolau
+        [windows] Chwilio Ffenestri
+       *[other] { "" }
+    }
+
+search-integration-label =
+    .label = Caniatáu i { search-engine-name } chwilio drwy'r negeseuon
+    .accesskey = C
+
+config-editor-button =
+    .label = Golygydd Ffurfweddu…
+    .accesskey = F
+
+return-receipts-description = Pennu sut mae { -brand-short-name } yn trin derbynebau
+return-receipts-button =
+    .label = Derbynebau Dychwelyd…
+    .accesskey = D
+
+update-app-legend = Diweddariadau { -brand-short-name }
+
+# Variables:
+#   $version (String): version of Thunderbird, e.g. 68.0.1
+update-app-version = Fersiwn { $version }
+
+allow-description = Gadael i { -brand-short-name } wneud
+automatic-updates-label =
+    .label = Gosod diweddariadau'n awtomatig (argymell: gwella diogelwch)
+    .accesskey = a
+check-updates-label =
+    .label = Gwirio am ddiweddariadau, ond gadael i mi ddewis i'w gosod a'i peidio
+    .accesskey = d
+
+update-history-button =
+    .label = Dangos Hanes Diweddaru
+    .accesskey = D
+
+use-service =
+    .label = Defnyddio gwasanaethau cefndirol i osod diweddariadau
+    .accesskey = e
+
+cross-user-udpate-warning = Bydd y gosodiad hwn yn berthnasol i holl gyfrifon Windows a phroffiliau { -brand-short-name } sy'n ddefnyddio'r gosodiad hwn { -brand-short-name }.
+
+networking-legend = Cysylltiad
+proxy-config-description = Ffurfweddu sut mae { -brand-short-name } yn cysylltu â'r Rhyngrwyd
+
+network-settings-button =
+    .label = Gosodiadau…
+    .accesskey = G
+
+offline-legend = All-lein
+offline-settings = Ffurfweddi gosodiadau all-lein
+
+offline-settings-button =
+    .label = All-lein…
+    .accesskey = l
+
+diskspace-legend = Lle ar Ddisg
+offline-compact-folder =
+    .label = Cywasgu pob ffolder pan fydd yn cadw dros gyfanswm o
+    .accesskey = y
+
+offline-compact-folder-automatically =
+    .label = Gofyn bob tro cyn cywasgu
+    .accesskey = G
+
+compact-folder-size =
+    .value = MB
+
+## Note: The entities use-cache-before and use-cache-after appear on a single
+## line in preferences as follows:
+## use-cache-before [ textbox for cache size in MB ] use-cache-after
+
+use-cache-before =
+    .value = Defnyddio hyd at
+    .accesskey = D
+
+use-cache-after = MB o le disg ar gyfer y storfa
+
+##
+
+smart-cache-label =
+    .label = Anwybyddu rheolaeth storfa awtomatig
+    .accesskey = A
+
+clear-cache-button =
+    .label = Clirio Nawr
+    .accesskey = N
+
+fonts-legend = Ffontiau a Lliwiau
+
+default-font-label =
+    .value = Ffont rhagosodedig:
+    .accesskey = r
+
+default-size-label =
+    .value = Maint:
+    .accesskey = M
+
+font-options-button =
+    .label = Uwch…
+    .accesskey = U
+
+color-options-button =
+    .label = Lliwiau…
+    .accesskey = L
+
+display-width-legend = Negeseuon Testun Plaen
+
+# Note : convert-emoticons-label 'Emoticons' are also known as 'Smileys', e.g. :-)
+convert-emoticons-label =
+    .label = Dangos gwenogluniau fel graffigau
+    .accesskey = g
+
+display-text-label = Wrth ddangos negeseuon testun plaen dyfynedig:
+
+style-label =
+    .value = Arddull:
+    .accesskey = A
+
+regular-style-item =
+    .label = Arferol
+bold-style-item =
+    .label = Trwm
+italic-style-item =
+    .label = Italig
+bold-italic-style-item =
+    .label = Italig Trwm
+
+size-label =
+    .value = Maint:
+    .accesskey = M
+
+regular-size-item =
+    .label = Arferol
+bigger-size-item =
+    .label = Mwy
+smaller-size-item =
+    .label = Llai
+
+quoted-text-color =
+    .label = Lliw:
+    .accesskey = L
+
+search-handler-table =
+    .placeholder = Hidlo mathau a gweithredoedd cynnwys
+
+type-column-header = Math o Gynnwys
+
+action-column-header = Gweithred
+
+save-to-label =
+    .label = Cadw ffeiliau yn
+    .accesskey = C
+
+choose-folder-label =
+    .label =
+        { PLATFORM() ->
+            [macos] Dewis…
+           *[other] Pori…
+        }
+    .accesskey =
+        { PLATFORM() ->
+            [macos] D
+           *[other] P
+        }
+
+always-ask-label =
+    .label = Gofyn i mi lle i gadw pob ffeil
+    .accesskey = G
+
+
+display-tags-text = Mae modd defnyddio tagiau i gategoreiddio a blaenoriaethu eich negeseuon.
+
+new-tag-button =
+    .label = Newydd…
+    .accesskey = N
+
+edit-tag-button =
+    .label = Golygu…
+    .accesskey = G
+
+delete-tag-button =
+    .label = Dileu
+    .accesskey = D
+
+auto-mark-as-read =
+    .label = Marcio'n awtomatig negeseuon wedi'u darllen
+    .accesskey = a
+
+mark-read-no-delay =
+    .label = Dangos yn syth
+    .accesskey = s
+
+view-attachments-inline =
+    .label = Gweld atodiadau mewn llinell
+    .accesskey = G
+
+## Note: This will concatenate to "After displaying for [___] seconds",
+## using (mark-read-delay) and a number (seconds-label).
+
+mark-read-delay =
+    .label = Ar ôl dangos am
+    .accesskey = d
+
+seconds-label = eiliad
+
+##
+
+open-msg-label =
+    .value = Agor neges mewn:
+
+open-msg-tab =
+    .label = Tab newydd
+    .accesskey = T
+
+open-msg-window =
+    .label = Ffenestr neges newydd
+    .accesskey = n
+
+open-msg-ex-window =
+    .label = Ffenestr neges gyfredol
+    .accesskey = g
+
+close-move-delete =
+    .label = Cau ffenestr/tab neges wrth symud neu ddileu
+    .accesskey = C
+
+display-name-label =
+    .value = Enw dangos:
+
+condensed-addresses-label =
+    .label = Dangos dim ond enw dangos unigolion yn fy llyfr cyfeiriadau
+    .accesskey = D
+
+## Compose Tab
+
+forward-label =
+    .value = Anfon negeseuon ymlaen:
+    .accesskey = y
+
+inline-label =
+    .label = Mewnlin
+
+as-attachment-label =
+    .label = Fel Atodiad
+
+extension-label =
+    .label = ychwanegu estyniad i enw ffeil
+    .accesskey = e
+
+## Note: This will concatenate to "Auto Save every [___] minutes",
+## using (auto-save-label) and a number (auto-save-end).
+
+auto-save-label =
+    .label = Awto Gadw pob
+    .accesskey = G
+
+auto-save-end = munud
+
+##
+
+warn-on-send-accel-key =
+    .label = Cadarnhau wrth ddefnyddio llwybr byr bysellfwrdd i anfon neges
+    .accesskey = b
+
+add-link-previews =
+    .label = Ychwanegu rhagolygon dolenni wrth ludo URLau
+    .accesskey = Y
+
+spellcheck-label =
+    .label = Gwirio sillafu cyn anfon
+    .accesskey = s
+
+spellcheck-inline-label =
+    .label = Galluogi gwirio sillafu wrth deipio
+    .accesskey = E
+
+language-popup-label =
+    .value = Iaith:
+    .accesskey = I
+
+download-dictionaries-link = Llwytho i Lawr Rhagor o Eiriaduron
+
+font-label =
+    .value = Ffont:
+    .accesskey = F
+
+font-size-label =
+    .value = Maint:
+    .accesskey = M
+
+default-colors-label =
+    .label = Defnyddio lliwiau rhagosodedig y darllenydd
+    .accesskey = d
+
+font-color-label =
+    .value = Lliw Testun:
+    .accesskey = L
+
+bg-color-label =
+    .value = Lliw Cefndir:
+    .accesskey = C
+
+restore-html-label =
+    .label = Adfer y Rhagosodiad
+    .accesskey = R
+
+default-format-label =
+    .label = Defnyddio'r Fformat Paragraff yn lle Testun Corff drwy ragosodiad
+    .accesskey = P
+
+compose-send-format-title = Fformat Anfon
+
+compose-send-automatic-option =
+    .label = Awtomatig
+
+compose-send-automatic-description = Os nad oes steilio'n cael ei ddefnyddio yn y neges, anfonwch Destun Plaen. Fel arall, anfonwch HTML gyda Thestun Plaen wrth gefn.
+
+compose-send-both-option =
+    .label = HTML a Thestun Plaen
+
+compose-send-both-description = Bydd rhaglen e-bost y derbynnydd yn pennu pa fersiwn i'w dangos.
+
+compose-send-html-option =
+    .label = Dim ond HTML
+
+compose-send-html-description = Efallai na fydd rhai derbynwyr yn gallu darllen y neges heb fod Testun Plaen wrth gefn.
+
+compose-send-plain-option =
+    .label = Dim ond Testun Plaen
+
+compose-send-plain-description = Bydd rhywfaint o steilio'n cael ei drosi i ddewis plaen arall, tra bydd nodweddion cyfansoddi eraill yn cael eu hanalluogi.
+
+autocomplete-description = Wrth gyfeirio negeseuon, chwilio am gofnodion cyfatebol yn:
+
+ab-label =
+    .label = Llyfrau Cyfeiriadau Lleol
+    .accesskey = L
+
+directories-label =
+    .label = Gweinydd Cyfeiriadur:
+    .accesskey = G
+
+directories-none-label =
+    .none = Dim
+
+edit-directories-label =
+    .label = Golygu Cyfeiriaduron…
+    .accesskey = C
+
+email-picker-label =
+    .label = Ychwanegu cyfeiriadau e-bost anfon yn awtomatig i'r:
+    .accesskey = Y
+
+default-directory-label =
+    .value = Cyfeiriadur cychwyn rhagosodedig yn ffenestr y llyfr cyfeiriadau:
+    .accesskey = c
+
+default-last-label =
+    .none = Cyfeiriadur defnyddiwyd ddiwethaf
+
+attachment-label =
+    .label = Gwirio am atodiadau coll
+    .accesskey = w
+
+attachment-options-label =
+    .label = Allweddeiriau…
+    .accesskey = w
+
+enable-cloud-share =
+    .label = Cynnig rhannu ffeiliau sy'n fwy na
+cloud-share-size =
+    .value = MB
+
+add-cloud-account =
+    .label = Ychwanegu…
+    .accesskey = Y
+    .defaultlabel = Ychwanegu…
+
+remove-cloud-account =
+    .label = Tynnu
+    .accesskey = T
+
+find-cloud-providers =
+    .value = Canfod rhagor o ddarparwyr…
+
+cloud-account-description = Ychwanegu gwasanaeth storio Filelink newydd
+
+## Privacy Tab
+
+mail-content = Cynnwys E-bost
+
+remote-content-label =
+    .label = Caniatáu cynnwys pell o fewn negeseuon
+    .accesskey = C
+
+exceptions-button =
+    .label = Eithriadau…
+    .accesskey = E
+
+remote-content-info =
+    .value = Dysgu rhagor am faterion preifatrwydd cynnwys pell
+
+web-content = Cynnwys Gwe
+
+history-label =
+    .label = Cofio gwefannau a dolenni rwyf wedi ymweld â nhw
+    .accesskey = o
+
+cookies-label =
+    .label = Derbyn cwcis gan wefannau
+    .accesskey = D
+
+third-party-label =
+    .value = Derbyn cwcis trydydd parti:
+    .accesskey = D
+
+third-party-always =
+    .label = Bob tro
+third-party-never =
+    .label = Byth
+third-party-visited =
+    .label = O'r ymwelwyd
+
+keep-label =
+    .value = Cadw tan:
+    .accesskey = C
+
+keep-expire =
+    .label = daw i ben
+keep-close =
+    .label = Cau { -brand-short-name }
+keep-ask =
+    .label = gofyn i mi bob tro
+
+cookies-button =
+    .label = Dangos Cwcis…
+    .accesskey = D
+
+do-not-track-label =
+    .label = Anfon neges “Dim Tracio” at wefannau nad ydych am gael eich tracio
+    .accesskey = D
+
+learn-button =
+    .label = Dysgu rhagor
+
+passwords-description = Mae { -brand-short-name } yn gallu cofio cyfrineiriau eich holl cyfrifon.
+
+passwords-button =
+    .label = Cyfrineiriau sydd wedi'u cadw…
+    .accesskey = C
+
+primary-password-description = Mae Prif Gyfrinair yn diogelu eich holl gyfrineiriau, ond rhaid i chi ei osod unwaith y sesiwn.
+
+primary-password-label =
+    .label = Defnyddio Prif Gyfrinair
+    .accesskey = D
+
+primary-password-button =
+    .label = Newid y Prif Gyfrinair…
+    .accesskey = N
+
+forms-primary-pw-fips-title = Rydych ym modd FIPS. Mae FIPS angen Prif Gyfrinair nad yw'n wag.
+forms-master-pw-fips-desc = Methodd Newid eich Cyfrinair
+
+
+junk-description = Yma gallwch osod eich gosodiadau sbam rhagosodedig. Mae modd ffurfweddu gosodiadau penodol ar gyfer sbam yn Gosodiadau Cyfrif.
+
+junk-label =
+    .label = Pan fyddai'n marcio negeseuon fel sbam:
+    .accesskey = P
+
+junk-move-label =
+    .label = Eu symud i ffolder "Sbam" y cyfrif
+    .accesskey = b
+
+junk-delete-label =
+    .label = Eu dileu
+    .accesskey = d
+
+junk-read-label =
+    .label = Marcio negeseuon Sbam fel rhai wedi'u darllen
+    .accesskey = a
+
+junk-log-label =
+    .label = Galluogi cofnodi hidlo sbam addasol
+    .accesskey = G
+
+junk-log-button =
+    .label = Dangos y cofnod
+    .accesskey = c
+
+reset-junk-button =
+    .label = Ailosod Data Hyfforddi
+    .accesskey = A
+
+phishing-description = Mae { -brand-short-name } yn gallu dadansoddi negeseuon am dwyll e-bost drwy edrych am dechnegau cyffredin i'ch twyllo.
+
+phishing-label =
+    .label = Dweud wrthyf os yw'r neges ryw'n ei darllen o bosib yn e-bost twyllodrus
+    .accesskey = D
+
+antivirus-description = Mae { -brand-short-name } yn gallu ei gwneud yn hawdd i feddalwedd gwrth firws ddadansoddi negeseuon e-byst sy'n cael eu derbyn am firysau cyn eu storio'n lleol.
+
+antivirus-label =
+    .label = Caniatáu i'r rhaglen neilltuo negeseuon sy'n cael eu derbyn
+    .accesskey = a
+
+certificate-description = Pan fydd gweinydd yn gofyn am fy nhystysgrif bersonol:
+
+certificate-auto =
+    .label = Dewis un yn awtomatig
+    .accesskey = D
+
+certificate-ask =
+    .label = Gofyn i mi bob tro
+    .accesskey = G
+
+ocsp-label =
+    .label = Ymholi gweinyddion ymatebydd OCSP i gadarnhau dilysrwydd cyfredol y tystysgrifau
+    .accesskey = Y
+
+certificate-button =
+    .label = Rheoli Tystysgrifau…
+    .accesskey = R
+
+security-devices-button =
+    .label = Dyfeisiau Diogelwch…
+    .accesskey = D
+
+## Chat Tab
+
+startup-label =
+    .value = Pan fydd { -brand-short-name } yn cychwyn:
+    .accesskey = P
+
+offline-label =
+    .label = Cadw fy Nghyfrifon Sgwrsio all-lein
+
+auto-connect-label =
+    .label = Cysylltu â fy nghyfrifon sgwrsio yn awtomatig
+
+## Note: idle-label is displayed first, then there's a field where the user
+## can enter a number, and itemTime is displayed at the end of the line.
+## The translations of the idle-label and idle-time-label parts don't have
+## to mean the exact same thing as in English; please try instead to
+## translate the whole sentence.
+
+idle-label =
+    .label = Hysbysu fy nghysylltiadau fy mod yn Segur ar ôl
+    .accesskey = S
+
+idle-time-label = munud o seibiant
+
+##
+
+away-message-label =
+    .label = a dynodi fy statws i I Ffwrdd gyda'r neges statws yma:
+    .accesskey = F
+
+send-typing-label =
+    .label = Anfon hysbysiadau teipio mewn trafodaethau
+    .accesskey = h
+
+notification-label = Pan fydd negeseuon wedi eu cyfeirio atoch chi yn cyrraedd:
+
+show-notification-label =
+    .label = Dangos rhybudd:
+    .accesskey = r
+
+notification-all =
+    .label = gydag enw'r anfonwr a rhagolwg o'r neges
+notification-name =
+    .label = gydag enw'r anfonwr yn unig
+notification-empty =
+    .label = heb unrhyw wybodaeth
+
+notification-type-label =
+    .label =
+        { PLATFORM() ->
+            [macos] Animeiddio eitem docio
+           *[other] Fflachio'r eitem bar tasgau
+        }
+    .accesskey =
+        { PLATFORM() ->
+            [macos] o
+           *[other] F
+        }
+
+chat-play-sound-label =
+    .label = Canu nodyn
+    .accesskey = C
+
+chat-play-button =
+    .label = Chwarae
+    .accesskey = h
+
+chat-system-sound-label =
+    .label = Sain rhagosodedig y system ar gyfer e-bost newydd
+    .accesskey = S
+
+chat-custom-sound-label =
+    .label = Defnyddio'r ffeil sain ganlynol
+    .accesskey = D
+
+chat-browse-sound-button =
+    .label = Pori…
+    .accesskey = P
+
+theme-label =
+    .value = Thema:
+    .accesskey = T
+
+style-mail =
+    .label = { -brand-short-name }
+style-bubbles =
+    .label = Swigod
+style-dark =
+    .label = Tywyll
+style-paper =
+    .label = Dalennau Papur
+style-simple =
+    .label = Syml
+
+preview-label = Rhagolwg:
+no-preview-label = Dim rhagolwg ar gael
+no-preview-description = Nid yw'r thema yma'n ddilys nac ar gael ar hyn o bryd (ychwanegyn wedi ei analluogi, modd diogel, …).
+
+chat-variant-label =
+    .value = Amrywiad:
+    .accesskey = A
+
+# This is used to determine the width of the search field in about:preferences,
+# in order to make the entire placeholder string visible
+#
+# Please keep the placeholder string short to avoid truncation.
+#
+# Notice: The value of the `.style` attribute is a CSS string, and the `width`
+# is the name of the CSS property. It is intended only to adjust the element's width.
+# Do not translate.
+search-preferences-input2 =
+    .style = width: 15.4em
+    .placeholder = Canfod yn y Gosodiadau
+
+## Settings UI Search Results
+
+search-results-header = Canlyniadau Chwilio
+
+# `<span data-l10n-name="query"></span>` will be replaced by the search term.
+search-results-empty-message2 =
+    { PLATFORM() ->
+        [windows] Ymddiheuriadau! Nid oes canlyniadau yn y Dewisiadau ar gyfer “<span data-l10n-name="query"></span>”.
+       *[other] Ymddiheuriadau! Nid oes canlyniadau yn y Dewisiadau ar gyfer “<span data-l10n-name="query"></span>”.
+    }
+
+search-results-help-link = Angen cymorth? Ewch i <a data-l10n-name="url">Cefnogaeth { -brand-short-name }</a>
diff --git a/l10n-cy/mail/messenger/preferences/receipts.ftl b/l10n-cy/mail/messenger/preferences/receipts.ftl
new file mode 100644
index 0000000000..50a528efb8
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/receipts.ftl
@@ -0,0 +1,51 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+receipts-dialog-window =
+    .title = Derbynebau Dychwelyd
+
+return-receipt-checkbox-control =
+    .label = Wrth anfon negeseuon, gofyn bob tro am dderbynneb dychwelyd
+    .accesskey = a
+
+receipt-arrive-label = Pan fydd derbynneb yn cyrraedd:
+
+receipt-leave-radio-control =
+    .label = Gadael yn fy Mlwch Derbyn
+    .accesskey = G
+
+receipt-move-radio-control =
+    .label = Symud i fy ffolder "Anfonwyd"
+    .accesskey = S
+
+receipt-request-label = Pan fyddaf yn derbyn cais am dderbynneb dychwelyd:
+
+receipt-return-never-radio-control =
+    .label = Peidio ag anfon derbynneb dychwelyd
+    .accesskey = P
+
+receipt-return-some-radio-control =
+    .label = Caniatáu derbynebau dychwelyd ar gyfer rhai negeseuon
+    .accesskey = C
+
+receipt-not-to-cc-label =
+    .value = Os nad wyf yn At neu Cc y neges:
+    .accesskey = O
+
+receipt-send-never-label =
+    .label = Byth anfon
+
+receipt-send-always-label =
+    .label = Anfon pob tro
+
+receipt-send-ask-label =
+    .label = Gofyn i mi
+
+sender-outside-domain-label =
+    .value = Os yw'r anfonwr y tu allan i'm parth:
+    .accesskey = s
+
+other-cases-text-label =
+    .value = Ym mhob achos arall:
+    .accesskey = Y
diff --git a/l10n-cy/mail/messenger/preferences/system-integration.ftl b/l10n-cy/mail/messenger/preferences/system-integration.ftl
new file mode 100644
index 0000000000..55635a5925
--- /dev/null
+++ b/l10n-cy/mail/messenger/preferences/system-integration.ftl
@@ -0,0 +1,46 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+system-integration-title =
+    .title = Integreiddio System
+
+system-integration-dialog =
+    .buttonlabelaccept = Gosod fel Rhagosodiad
+    .buttonlabelcancel = Hepgor Integreiddio
+    .buttonlabelcancel2 = Diddymu
+
+default-client-intro = Defnyddio { -brand-short-name } fel y rhaglen rhagosodedig ar gyfer:
+
+unset-default-tooltip = Nid yw'n bosib dadosod { -brand-short-name } fel y cleient rhagosodedig o fewn { -brand-short-name }. I wneud rhaglen arall y rhagosodedig rhaid defnyddio ei ddeialog 'Gosod fel y rhagosodedig' ei hun.
+
+checkbox-email-label =
+    .label = E-Bost
+    .tooltiptext = { unset-default-tooltip }
+checkbox-newsgroups-label =
+    .label = Grwpiau Newyddion
+    .tooltiptext = { unset-default-tooltip }
+checkbox-feeds-label =
+    .label = Llif
+    .tooltiptext = { unset-default-tooltip }
+
+checkbox-calendar-label =
+    .label = Calendr
+    .tooltiptext = { unset-default-tooltip }
+
+# Note: This is the search engine name for all the different platforms.
+# Platforms that don't support it should be left blank.
+system-search-engine-name =
+    { PLATFORM() ->
+        [macos] Sbotolau
+        [windows] Chwilio Ffenestri
+       *[other] { "" }
+    }
+
+system-search-integration-label =
+    .label = Caniatáu i { system-search-engine-name } chwilio drwy'r negeseuon
+    .accesskey = C
+
+check-on-startup-label =
+    .label = Gwirio hwn bob tro wrth gychwyn { -brand-short-name }
+    .accesskey = G
diff --git a/l10n-cy/mail/messenger/shortcuts.ftl b/l10n-cy/mail/messenger/shortcuts.ftl
new file mode 100644
index 0000000000..6d77e41549
--- /dev/null
+++ b/l10n-cy/mail/messenger/shortcuts.ftl
@@ -0,0 +1,113 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+## Shortcuts
+
+# Variables:
+#  $key (String) - The shortcut key.
+shortcut-key = { $key }
+
+meta-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌘ { $key }
+       *[other] Meta+{ $key }
+    }
+
+ctrl-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌃ { $key }
+       *[other] Ctrl+{ $key }
+    }
+
+shift-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⇧ { $key }
+       *[other] Shift+{ $key }
+    }
+
+alt-shortcut-key =
+    { PLATFORM() ->
+        [macos] Shift+{ $key }
+       *[other] Alt+{ $key }
+    }
+
+meta-ctrl-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌃ ⌘ { $key }
+       *[other] Meta+Ctrl+{ $key }
+    }
+
+meta-alt-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌥ ⌘ { $key }
+       *[other] Meta+Alt+{ $key }
+    }
+
+ctrl-alt-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌃ ⌥ { $key }
+       *[other] Ctrl+Alt+{ $key }
+    }
+
+meta-ctrl-alt-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌃ ⌥ ⌘ { $key }
+       *[other] Meta+Ctrl+Alt+{ $key }
+    }
+
+meta-shift-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⇧ ⌘ { $key }
+       *[other] Meta+Shift+{ $key }
+    }
+
+ctrl-shift-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌃ ⇧ { $key }
+       *[other] Ctrl+Shift+{ $key }
+    }
+
+meta-ctrl-shift-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌃ ⇧ ⌘ { $key }
+       *[other] Meta+Ctrl+Shift+{ $key }
+    }
+
+alt-shift-shortcut-key =
+    { PLATFORM() ->
+        [macos] ⌥ ⇧ { $key }
+       *[other] Alt+Shift+{ $key }
+    }
+
+meta-shift-alt-shortcut-key2 =
+    { PLATFORM() ->
+        [macos] ⌥ ⇧ ⌘ { $key }
+       *[other] Meta+Alt+Shift+{ $key }
+    }
+
+ctrl-shift-alt-shortcut-key2 =
+    { PLATFORM() ->
+        [macos] ⌃ ⌥ ⇧ { $key }
+       *[other] Ctrl+Alt+Shift+{ $key }
+    }
+
+meta-ctrl-shift-alt-shortcut-key2 =
+    { PLATFORM() ->
+        [macos] ⌃ ⌥ ⇧ ⌘ { $key }
+       *[other] Meta+Ctrl+Alt+Shift+{ $key }
+    }
+
+# Variables:
+#  $title (String): The title coming from the original element.
+#  $shortcut (String): The shortcut generated from the keystroke combination.
+button-shortcut-string =
+    .title = { $title } ({ $shortcut })
+
+# Variables:
+#  $label (String): The text label coming from the original element.
+#  $shortcut (String): The shortcut generated from the keystroke combination.
+menuitem-shortcut-string =
+    .label = { $label }
+    .acceltext = { $shortcut }
diff --git a/l10n-cy/mail/messenger/troubleshootMode.ftl b/l10n-cy/mail/messenger/troubleshootMode.ftl
new file mode 100644
index 0000000000..8d3b25b88f
--- /dev/null
+++ b/l10n-cy/mail/messenger/troubleshootMode.ftl
@@ -0,0 +1,39 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+troubleshoot-mode-window =
+    .title = Modd Datrys Problemau { -brand-short-name }
+    .style = width: 37em;
+
+troubleshoot-mode-description = Defnyddiwch y modd arbennig hwn o { -brand-short-name } i ddatrys materion. Bydd eich estyniadau a'ch cyfaddasiadau yn cael eu hanalluogi dros dro.
+
+troubleshoot-mode-description2 = Gallwch wneud rhai neu'r cyfan o'r newidiadau hyn yn rhai parhaol:
+
+troubleshoot-mode-disable-addons =
+    .label = Analluogi pob ychwanegyn
+    .accesskey = A
+
+troubleshoot-mode-reset-toolbars =
+    .label = Ailosod barau offer a rheolyddion
+    .accesskey = b
+
+troubleshoot-mode-change-and-restart =
+    .label = Gwneud Newidiadau ac Ailgychwyn
+    .accesskey = G
+
+troubleshoot-mode-continue =
+    .label = Parhau yn y Modd Datrys Problemau
+    .accesskey = P
+
+troubleshoot-mode-quit =
+    .label =
+        { PLATFORM() ->
+            [windows] Gadael
+           *[other] Gorffen
+        }
+    .accesskey =
+        { PLATFORM() ->
+            [windows] a
+           *[other] o
+        }
diff --git a/l10n-cy/mail/messenger/viewSource.ftl b/l10n-cy/mail/messenger/viewSource.ftl
new file mode 100644
index 0000000000..63d5e05e3f
--- /dev/null
+++ b/l10n-cy/mail/messenger/viewSource.ftl
@@ -0,0 +1,19 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+context-text-action-find =
+    .label = Canfod
+    .accesskey = C
+
+context-text-action-find-again =
+    .label = Canfod Eto
+    .accesskey = C
+
+text-action-find =
+    .label = Canfod
+    .accesskey = C
+
+text-action-find-again =
+    .label = Canfod Eto
+    .accesskey = C
diff --git a/l10n-cy/mail/updater/updater.ini b/l10n-cy/mail/updater/updater.ini
new file mode 100644
index 0000000000..d31b5fc786
--- /dev/null
+++ b/l10n-cy/mail/updater/updater.ini
@@ -0,0 +1,7 @@
+; This Source Code Form is subject to the terms of the Mozilla Public
+; License, v. 2.0. If a copy of the MPL was not distributed with this
+; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+; This file is in the UTF-8 encoding
+[Strings]
+TitleText=Diweddaru %MOZ_APP_DISPLAYNAME%
+InfoText=Mae %MOZ_APP_DISPLAYNAME% yn gosod eich diweddariadau a bydd yn cychwyn ymhen ychydig…