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-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/AccountManager.dtd23
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/AccountWizard.dtd55
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/CustomHeaders.dtd11
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/FilterEditor.dtd66
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/FilterListDialog.dtd41
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/SearchDialog.dtd41
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutDownloads.dtd23
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutRights.properties6
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutSupportMail.properties15
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/accountCreationModel.properties21
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/accountCreationUtil.properties34
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/activity.dtd19
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/activity.properties99
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addbuddy.dtd7
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abAddressBookNameDialog.dtd7
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abContactsPanel.dtd49
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abMailListDialog.dtd22
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abMainWindow.dtd17
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abResultsPane.dtd38
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/addressBook.properties178
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/ldapAutoCompErrs.properties109
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/pref-directory-add.dtd45
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/pref-directory.dtd17
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/replicationProgress.properties20
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-addressing.dtd51
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-advanced.dtd31
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-archiveoptions.dtd26
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-copies.dtd53
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-e2e.properties5
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-identities-list.dtd15
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-identity-edit.dtd17
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-im.dtd16
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-junk.dtd31
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-main.dtd47
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-mdn.dtd33
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-mdn.properties6
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-offline.dtd57
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-server-advanced.dtd31
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-server-top.dtd89
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-serverwithnoidentities.dtd6
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-smime.dtd47
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-smime.properties39
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/appUpdate.properties40
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/appleMailImportMsgs.properties21
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/baseMenuOverlay.dtd35
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/beckyImportMsgs.properties19
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/charsetTitles.properties84
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/chat.dtd44
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/chat.properties110
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/configEditorOverlay.dtd5
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/converterDialog.dtd11
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/converterDialog.properties41
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/custom.properties5
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/customizeToolbar.dtd18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/customizeToolbar.properties11
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/downloadheaders.dtd27
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/editContactOverlay.dtd20
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/editContactOverlay.properties14
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/fieldMapImport.dtd17
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/filter.properties108
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderProps.dtd70
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderWidgets.properties12
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderpane.dtd7
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/gloda.properties175
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaComplete.properties19
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaFacetView.dtd29
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaFacetView.properties171
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imAccountWizard.dtd32
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imAccounts.properties63
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imapMsgs.properties266
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/importDialog.dtd48
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/importMsgs.properties307
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/joinChat.dtd10
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/junkLog.dtd10
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/localMsgs.properties140
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailEditorOverlay.dtd6
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailOverlay.dtd11
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailViewList.dtd9
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailViewSetup.dtd12
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailviews.properties13
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/markByDate.dtd9
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.dtd920
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.properties768
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdAdvancedEdit.dtd18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdColorPicker.dtd22
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdConvertToTable.dtd15
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdDialogOverlay.dtd18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdNamedAnchorProperties.dtd9
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorColorProperties.dtd29
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorHLineProperties.dtd27
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorImageProperties.dtd81
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertChars.dtd19
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertMath.dtd21
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertSource.dtd15
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertTOC.dtd16
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertTable.dtd18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorLinkProperties.dtd6
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorListProperties.dtd20
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorPersonalDictionary.dtd18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorReplace.dtd27
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorSpellCheck.dtd38
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorTableProperties.dtd75
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/composeMsgs.properties463
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/editor.properties208
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/editorOverlay.dtd304
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/mailComposeEditorOverlay.dtd9
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/messengercompose.dtd306
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/sendProgress.dtd8
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/sendProgress.properties21
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/migration/migration.dtd30
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/migration/migration.properties30
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mime.properties154
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mimeheader.properties35
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/morkImportMsgs.properties18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgAccountCentral.dtd26
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgHdrViewOverlay.dtd114
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgSynchronize.dtd27
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgViewPickerOverlay.dtd22
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgmdn.properties18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/multimessageview.dtd8
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/multimessageview.properties66
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/newFolderDialog.dtd16
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/news.properties56
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/newsError.dtd31
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/offline.properties28
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/offlineStartup.properties8
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/outlookImportMsgs.properties72
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/pgpmime.properties10
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/applicationManager.properties13
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/applications.properties13
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/messagestyle.properties13
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/preferences.properties100
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/prefs.properties90
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/profileDowngrade.dtd20
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/removeAccount.dtd22
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/removeAccount.properties5
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/renameFolderDialog.dtd9
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/sanitize.dtd36
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/seamonkeyImportMsgs.properties18
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search-attributes.properties45
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search-operators.properties31
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search.properties27
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/searchTermOverlay.dtd19
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/shutdownWindow.properties10
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/smime.properties13
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/smtpEditOverlay.dtd24
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/subscribe.dtd22
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/subscribe.properties13
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/tabmail.dtd9
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/taskbar.properties8
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/telemetry.properties13
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/templateUtils.properties7
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/textImportMsgs.properties53
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/vCardImportMsgs.properties26
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewLog.dtd12
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewSource.dtd86
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewSource.properties17
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewZoomOverlay.dtd32
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/virtualFolderListDialog.dtd10
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/virtualFolderProperties.dtd22
-rw-r--r--thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/wmImportMsgs.properties76
161 files changed, 8794 insertions, 0 deletions
diff --git a/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/AccountManager.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/AccountManager.dtd
new file mode 100644
index 0000000000..74ef98c110
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/AccountManager.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/. -->
+
+<!-- extracted from AccountManager.xhtml -->
+
+<!ENTITY accountManagerTitle.label "Gosodiadau 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">
diff --git a/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/AccountWizard.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/AccountWizard.dtd
new file mode 100644
index 0000000000..5f53834437
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/CustomHeaders.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/CustomHeaders.dtd
new file mode 100644
index 0000000000..f2167621cc
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/FilterEditor.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/FilterEditor.dtd
new file mode 100644
index 0000000000..0e1332a5ff
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/FilterEditor.dtd
@@ -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/. -->
+
+<!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 Darllen">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/FilterListDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/FilterListDialog.dtd
new file mode 100644
index 0000000000..781665cd40
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/SearchDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/SearchDialog.dtd
new file mode 100644
index 0000000000..c575b26463
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutDownloads.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutDownloads.dtd
new file mode 100644
index 0000000000..cac1c99e4b
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 Ffolder Cynhwysol">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutRights.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutRights.properties
new file mode 100644
index 0000000000..2a9f1b93dd
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutSupportMail.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/aboutSupportMail.properties
new file mode 100644
index 0000000000..ad47fddc4c
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/accountCreationModel.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/accountCreationModel.properties
new file mode 100644
index 0000000000..3ac780124a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/accountCreationUtil.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/accountCreationUtil.properties
new file mode 100644
index 0000000000..46728d91bd
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/activity.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/activity.dtd
new file mode 100644
index 0000000000..cdf84fd424
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/activity.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/activity.properties
new file mode 100644
index 0000000000..7a4cd2eedc
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addbuddy.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addbuddy.dtd
new file mode 100644
index 0000000000..bafd30d80c
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abAddressBookNameDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abAddressBookNameDialog.dtd
new file mode 100644
index 0000000000..917b01a884
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abContactsPanel.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abContactsPanel.dtd
new file mode 100644
index 0000000000..1117163995
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abMailListDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abMailListDialog.dtd
new file mode 100644
index 0000000000..71a6610451
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abMainWindow.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abMainWindow.dtd
new file mode 100644
index 0000000000..09a89e3c59
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abResultsPane.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/abResultsPane.dtd
new file mode 100644
index 0000000000..f0f9f2fa31
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Ffôn Symudol">
+<!ENTITY CellularNumber.accesskey "S">
+<!ENTITY PagerNumber.label "Swnyn">
+<!ENTITY PagerNumber.accesskey "w">
+<!ENTITY FaxNumber.label "Ffacs">
+<!ENTITY FaxNumber.accesskey "F">
+<!ENTITY HomePhone.label "Rhif 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/addressBook.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/addressBook.properties
new file mode 100644
index 0000000000..a2e63b5753
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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=Ffôn 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$S.
+
+# For locked .mab files
+lockedMabFileTitle=Methu Llwytho Ffeil Llyfr Cyfeiriadau
+lockedMabFileAlert=Methu llwytho ffeil llyfr cyfeiriadau %S. Gall fod yn darllen yn unig, neu wedi ei gloi gan raglen arall. Ceisiwch eto yn ddiweddarach.
diff --git a/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/ldapAutoCompErrs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/ldapAutoCompErrs.properties
new file mode 100644
index 0000000000..096f8e817a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/ldapAutoCompErrs.properties
@@ -0,0 +1,109 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# These are error strings for problems that happen while in the
+# various states declared in nsILDAPAutoCompFormatter.idl. Note that
+# the number that indexes each error state is the same as the number
+# corresponding to that state in nsILDAPAutoCompFormatter.idl.
+
+# These are error strings for problems that happen while in the
+# various states declared in nsILDAPAutoCompFormatter.idl. Note that
+# the number that indexes each error state is the same as the number
+# corresponding to that state in nsILDAPAutoCompFormatter.idl.
+
+## @name ERR_STATE_UNBOUND
+## @loc none
+0=Anhawster cychwyn LDAP
+
+## @name ERR_STATE_INITIALIZING
+## @loc none
+1=Methodd cysylltiad gweinydd LDAP
+
+## @name ERR_STATE_BINDING
+## @loc none
+2=Methodd cysylltiad gweinydd LDAP
+
+## @name ERR_STATE_BOUND
+## @loc none
+3=Problem cyfathrebu gweinydd LDAP
+
+## @name ERR_STATE_SEARCHING
+## @loc none
+4=Problem chwilio gweinydd LDAP
+
+
+# The format of the alert dialog itself
+#
+## @name ALERT_FORMAT
+## @loc None of %1$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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/pref-directory-add.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/pref-directory-add.dtd
new file mode 100644
index 0000000000..4e18369be7
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/pref-directory.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/pref-directory.dtd
new file mode 100644
index 0000000000..93db1fa36e
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/replicationProgress.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/addressbook/replicationProgress.properties
new file mode 100644
index 0000000000..26a24ca271
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-addressing.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-addressing.dtd
new file mode 100644
index 0000000000..bb0c68dce8
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-advanced.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-advanced.dtd
new file mode 100644
index 0000000000..763eaaa5b6
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-archiveoptions.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-archiveoptions.dtd
new file mode 100644
index 0000000000..b1517343ce
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-copies.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-copies.dtd
new file mode 100644
index 0000000000..d791632db6
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-e2e.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-e2e.properties
new file mode 100644
index 0000000000..dbc7881dde
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-identities-list.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-identities-list.dtd
new file mode 100644
index 0000000000..24527f0212
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-identity-edit.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-identity-edit.dtd
new file mode 100644
index 0000000000..ceb7e18e09
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-im.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-im.dtd
new file mode 100644
index 0000000000..5a1c3e828a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Arallenw:">
+<!ENTITY account.newMailNotification "Hysbysu am 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-junk.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-junk.dtd
new file mode 100644
index 0000000000..d50ab0e944
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-main.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-main.dtd
new file mode 100644
index 0000000000..25a30b359f
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-main.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/. -->
+
+<!-- extracted from am-main.xhtml -->
+
+<!ENTITY accountTitle.label "Gosodiadau 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-mdn.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-mdn.dtd
new file mode 100644
index 0000000000..c98c1e4473
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-mdn.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-mdn.properties
new file mode 100644
index 0000000000..26c43e5a61
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-offline.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-offline.dtd
new file mode 100644
index 0000000000..9bafc66069
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-server-advanced.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-server-advanced.dtd
new file mode 100644
index 0000000000..5159965a50
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-server-top.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-server-top.dtd
new file mode 100644
index 0000000000..6c4a69823e
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-serverwithnoidentities.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-serverwithnoidentities.dtd
new file mode 100644
index 0000000000..af82c6f129
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-smime.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-smime.dtd
new file mode 100644
index 0000000000..a69f3598f8
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-smime.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/am-smime.properties
new file mode 100644
index 0000000000..27fd773de7
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/appUpdate.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/appUpdate.properties
new file mode 100644
index 0000000000..ca3d623504
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/appleMailImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/appleMailImportMsgs.properties
new file mode 100644
index 0000000000..b47b5aaed7
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/baseMenuOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/baseMenuOverlay.dtd
new file mode 100644
index 0000000000..cd516d5f2d
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/beckyImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/beckyImportMsgs.properties
new file mode 100644
index 0000000000..4c22395c01
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/charsetTitles.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/charsetTitles.properties
new file mode 100644
index 0000000000..d5d60eda3d
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/chat.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/chat.dtd
new file mode 100644
index 0000000000..24d534cd34
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/chat.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/chat.properties
new file mode 100644
index 0000000000..ac3dfee9f9
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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=Enw Dangos
+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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/configEditorOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/configEditorOverlay.dtd
new file mode 100644
index 0000000000..3d78799d68
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/converterDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/converterDialog.dtd
new file mode 100644
index 0000000000..e39851e4d7
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Parhau">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/converterDialog.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/converterDialog.properties
new file mode 100644
index 0000000000..9bba0f3c62
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/custom.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/custom.properties
new file mode 100644
index 0000000000..d4ca87a701
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/customizeToolbar.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/customizeToolbar.dtd
new file mode 100644
index 0000000000..780210c7f5
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 at neu o'r 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/customizeToolbar.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/customizeToolbar.properties
new file mode 100644
index 0000000000..3b1e6eafed
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/downloadheaders.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/downloadheaders.dtd
new file mode 100644
index 0000000000..88e3ddc178
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/editContactOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/editContactOverlay.dtd
new file mode 100644
index 0000000000..d8dff07314
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/editContactOverlay.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/editContactOverlay.properties
new file mode 100644
index 0000000000..f2a19d2916
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/fieldMapImport.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/fieldMapImport.dtd
new file mode 100644
index 0000000000..1212ff9141
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/filter.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/filter.properties
new file mode 100644
index 0000000000..4c1575a1b4
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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=anfonwyd 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 ei darllen
+# 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderProps.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderProps.dtd
new file mode 100644
index 0000000000..01cf7355f2
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 sy'n fwy 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 bob 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderWidgets.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderWidgets.properties
new file mode 100644
index 0000000000..595d8a00d7
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 y Cyfan (%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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderpane.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/folderpane.dtd
new file mode 100644
index 0000000000..4b79e3641a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 Darllen">
+<!ENTITY totalColumn.label "Cyfanswm">
+<!ENTITY folderSizeColumn.label "Maint">
diff --git a/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/gloda.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/gloda.properties
new file mode 100644
index 0000000000..97ce684f5f
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 email 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=Anfonwyd Ymlaen
+
+# LOCALIZATION NOTE (gloda.mimetype.category.*.label): Map categories of MIME
+# types defined in MimeTypeCategories 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 email 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaComplete.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaComplete.properties
new file mode 100644
index 0000000000..e407e1a7f1
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaFacetView.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaFacetView.dtd
new file mode 100644
index 0000000000..5bf0e3c049
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaFacetView.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/glodaFacetView.properties
new file mode 100644
index 0000000000..3fad3fc0a3
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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=Newid y 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imAccountWizard.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imAccountWizard.dtd
new file mode 100644
index 0000000000..8e379415ea
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Arallenw:">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imAccounts.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imAccounts.properties
new file mode 100644
index 0000000000..7a14e00c56
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imapMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/imapMsgs.properties
new file mode 100644
index 0000000000..f0dd5afeea
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 manylion mewngofnodi…
+
+# Status - auth logon
+imapStatusSendingAuthLogin=Anfon manylion 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=Darllenwyd
+
+imapAclSeenRight=Gosod Cyflwr Darllen/Heb ei Darllen
+
+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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/importDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/importDialog.dtd
new file mode 100644
index 0000000000..26a97a8c7e
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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'r Cyfan">
+<!ENTITY importAll.accesskey "M">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/importMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/importMsgs.properties
new file mode 100644
index 0000000000..ab7c517e95
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/joinChat.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/joinChat.dtd
new file mode 100644
index 0000000000..ff1971209f
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/junkLog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/junkLog.dtd
new file mode 100644
index 0000000000..96e6d35a7c
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/localMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/localMsgs.properties
new file mode 100644
index 0000000000..c630b36588
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailEditorOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailEditorOverlay.dtd
new file mode 100644
index 0000000000..64728f3361
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailOverlay.dtd
new file mode 100644
index 0000000000..5b7c0eab37
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailViewList.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailViewList.dtd
new file mode 100644
index 0000000000..f2f599b051
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailViewSetup.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailViewSetup.dtd
new file mode 100644
index 0000000000..49b1a15a8d
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailviews.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mailviews.properties
new file mode 100644
index 0000000000..380ce9ec25
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/markByDate.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/markByDate.dtd
new file mode 100644
index 0000000000..6b5772f28e
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.dtd
new file mode 100644
index 0000000000..126fcb0f60
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.dtd
@@ -0,0 +1,920 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+ - License, v. 2.0. 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 selectMenu.label "Dewis">
+<!ENTITY selectMenu.accesskey "w">
+<!ENTITY all.label "Y Cyfan">
+<!ENTITY all.accesskey "C">
+<!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 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 Darllen">
+<!ENTITY redoMarkAllCmd.label "Ail-wneud Marcio'r Cyfan Wedi'u Darllen">
+<!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 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 "Y Cyfan">
+<!ENTITY allFolders.accesskey "C">
+<!ENTITY unreadFolders.label "Heb ei Darllen">
+<!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 "Y Cyfan">
+<!ENTITY allMsgsCmd.accesskey "C">
+<!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 Darllen">
+<!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 "Y Cyfan">
+<!ENTITY headersAllCmd.accesskey "C">
+<!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 Serennog">
+<!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">
+<!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 Darllen">
+<!ENTITY markAsReadCmd.accesskey "W">
+<!ENTITY markAsUnreadCmd.label "Heb ei Darllen">
+<!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 "Y Cyfan Wedi eu Darllen">
+<!ENTITY markAllReadCmd.accesskey "D">
+<!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 "Newid Tudalen Gwe 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 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 Darllen">
+<!ENTITY nextMsgButton.label "Nesaf">
+<!ENTITY previousButton.label "Blaenorol">
+<!ENTITY previousButtonToolbarItem.label "Blaenorol Heb ei Darllen">
+<!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 appmenuToolbarLayout.label "Cynllun Bar Offer…">
+
+<!-- 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 Darllen">
+<!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 "Newid 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 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 "Dod â'r 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 y Cyfan">
+
+<!-- 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.properties
new file mode 100644
index 0000000000..1ee428ea2e
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messenger.properties
@@ -0,0 +1,768 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. 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-ddewis 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdAdvancedEdit.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdAdvancedEdit.dtd
new file mode 100644
index 0000000000..3521a919ef
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdColorPicker.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdColorPicker.dtd
new file mode 100644
index 0000000000..29829fba85
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdConvertToTable.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdConvertToTable.dtd
new file mode 100644
index 0000000000..aa9975e3fe
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Bwlch">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdDialogOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdDialogOverlay.dtd
new file mode 100644
index 0000000000..9cae389251
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdDialogOverlay.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 AdvancedEditButton.label "Golygu Uwch…">
+<!ENTITY AdvancedEditButton.accessKey "G">
+<!ENTITY AdvancedEditButton.tooltip "Ychwanegu neu newid Priodweddau HTML, priodoleddau 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.">
+
+<!-- Shared by Link and Image dialogs -->
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdNamedAnchorProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EdNamedAnchorProperties.dtd
new file mode 100644
index 0000000000..510508d130
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorColorProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorColorProperties.dtd
new file mode 100644
index 0000000000..2dffbd577a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorHLineProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorHLineProperties.dtd
new file mode 100644
index 0000000000..659a9ae24b
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorImageProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorImageProperties.dtd
new file mode 100644
index 0000000000..a01b54400d
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertChars.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertChars.dtd
new file mode 100644
index 0000000000..494e858a23
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertMath.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertMath.dtd
new file mode 100644
index 0000000000..c3533186a1
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertSource.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertSource.dtd
new file mode 100644
index 0000000000..09877577a5
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertTOC.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertTOC.dtd
new file mode 100644
index 0000000000..e30f42dfb2
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertTable.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorInsertTable.dtd
new file mode 100644
index 0000000000..9a6acaa5f3
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorLinkProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorLinkProperties.dtd
new file mode 100644
index 0000000000..8f775351aa
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorListProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorListProperties.dtd
new file mode 100644
index 0000000000..15216ed8a2
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorPersonalDictionary.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorPersonalDictionary.dtd
new file mode 100644
index 0000000000..d14a116c40
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorReplace.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorReplace.dtd
new file mode 100644
index 0000000000..9b54634f37
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorReplace.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 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 "Amnewid">
+<!ENTITY replaceButton.accesskey "N">
+<!ENTITY replaceAndFindButton.label "Newid a Chanfod">
+<!ENTITY replaceAndFindButton.accesskey "N">
+<!ENTITY replaceAllButton.label "Newid y Cyfan">
+<!ENTITY replaceAllButton.accesskey "N">
+<!ENTITY closeButton.label "Cau">
+<!ENTITY closeButton.accesskey "C">
diff --git a/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorSpellCheck.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorSpellCheck.dtd
new file mode 100644
index 0000000000..a7dd582ef1
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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'r Cyfan">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorTableProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/EditorTableProperties.dtd
new file mode 100644
index 0000000000..9bf6920a4b
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Symudol">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/composeMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/composeMsgs.properties
new file mode 100644
index 0000000000..baf2c4c919
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/composeMsgs.properties
@@ -0,0 +1,463 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. 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 (smtpTooManyRecipients): argument %s is the Outgoing server (SMTP) response
+smtpTooManyRecipients=Heb anfon y neges oherwydd ei bod yn fwy na'r nifer sy'n cael ei ganiatáu o dderbynwyr. Ymatebodd 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/editor.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/editor.properties
new file mode 100644
index 0000000000..62a5d47d26
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/editorOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/editorOverlay.dtd
new file mode 100644
index 0000000000..63925f16cb
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/editorOverlay.dtd
@@ -0,0 +1,304 @@
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+ - License, v. 2.0. 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 "Symudol">
+<!ENTITY tableCells.label "Cell(oedd)">
+<!ENTITY tableCell.accesskey "S">
+<!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">
+
+<!-- Toolbar-only items -->
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/mailComposeEditorOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/mailComposeEditorOverlay.dtd
new file mode 100644
index 0000000000..331520180c
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/messengercompose.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/messengercompose.dtd
new file mode 100644
index 0000000000..58a5fa335f
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 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-At">
+<!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 y Cyfan">
+<!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 Atodiad 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/sendProgress.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/sendProgress.dtd
new file mode 100644
index 0000000000..0bc736e9f1
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/sendProgress.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/messengercompose/sendProgress.properties
new file mode 100644
index 0000000000..2682ce0cf3
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/migration/migration.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/migration/migration.dtd
new file mode 100644
index 0000000000..c971fb91ae
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/migration/migration.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/migration/migration.properties
new file mode 100644
index 0000000000..e641610a4d
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/migration/migration.properties
@@ -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/.
+
+profileName_format=%S %S
+
+# Import Sources
+1_seamonkey=Dewisiadau
+1_thunderbird=Dewisiadau
+
+2_seamonkey=Gosodiadau Cyfrif
+2_thunderbird=Gosodiadau Cyfrif
+2_outlook=Gosodiadau 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mime.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mime.properties
new file mode 100644
index 0000000000..f4e27121ca
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mimeheader.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/mimeheader.properties
new file mode 100644
index 0000000000..44e193e3d4
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/morkImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/morkImportMsgs.properties
new file mode 100644
index 0000000000..d3ea8d0c73
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgAccountCentral.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgAccountCentral.dtd
new file mode 100644
index 0000000000..ff1f6cf3db
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Sgwrsio">
+
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgHdrViewOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgHdrViewOverlay.dtd
new file mode 100644
index 0000000000..1589be5c06
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Cyfeirnodau">
+<!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 mewn 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 Darllen">
+<!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 y Cyfan…">
+<!ENTITY openAllAttachmentsCmd.accesskey "A">
+<!ENTITY saveAllAttachmentsCmd.label "Cadw'r Cyfan…">
+<!ENTITY saveAllAttachmentsCmd.accesskey "C">
+<!ENTITY detachAllAttachmentsCmd.label "Datod y Cyfan…">
+<!ENTITY detachAllAttachmentsCmd.accesskey "a">
+<!ENTITY deleteAllAttachmentsCmd.label "Dileu'r Cyfan…">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgSynchronize.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgSynchronize.dtd
new file mode 100644
index 0000000000..419fba268d
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgViewPickerOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgViewPickerOverlay.dtd
new file mode 100644
index 0000000000..708286c32a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgViewPickerOverlay.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/. -->
+
+<!--LOCALIZATION NOTE msgViewPickerOverlay.dtd UI for showing various views on a folder -->
+
+<!ENTITY viewPicker.label "Golwg:">
+<!ENTITY viewPicker.accesskey "l">
+<!ENTITY viewAll.label "Y Cyfan">
+<!ENTITY viewAll.accesskey "C">
+<!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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgmdn.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/msgmdn.properties
new file mode 100644
index 0000000000..01b99ca3ea
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/multimessageview.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/multimessageview.dtd
new file mode 100644
index 0000000000..1e83dd68eb
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/multimessageview.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/multimessageview.properties
new file mode 100644
index 0000000000..829b46a509
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/newFolderDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/newFolderDialog.dtd
new file mode 100644
index 0000000000..3686b6f68a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/news.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/news.properties
new file mode 100644
index 0000000000..6d3f1227c2
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/newsError.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/newsError.dtd
new file mode 100644
index 0000000000..562dc2e297
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/offline.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/offline.properties
new file mode 100644
index 0000000000..e0a35839ba
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/offlineStartup.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/offlineStartup.properties
new file mode 100644
index 0000000000..ca05774262
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/outlookImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/outlookImportMsgs.properties
new file mode 100644
index 0000000000..54e26c51e0
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/outlookImportMsgs.properties
@@ -0,0 +1,72 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. 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 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=Llyfr cyfeiriadau wedi'i fewnforio %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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/pgpmime.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/pgpmime.properties
new file mode 100644
index 0000000000..e60b6a0d15
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/applicationManager.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/applicationManager.properties
new file mode 100644
index 0000000000..4f566cf64b
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/applications.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/applications.properties
new file mode 100644
index 0000000000..ff84d06f03
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/messagestyle.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/messagestyle.properties
new file mode 100644
index 0000000000..16460e1b1a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/preferences.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/preferences/preferences.properties
new file mode 100644
index 0000000000..f413b3e02c
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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$S)
+
+#### Sound Notifications
+soundFilePickerTitle=Dewis Sain
+
+#### Remote content
+imagepermissionstext=Mae modd i chi bennu pa ddelweddau gwefannau a chynnwys pell eraill sy'n cael caniatâd i'w llwytho. Mae hefyd modd i chi ganiatáu'r holl gynnwys pell yn seiliedig ar gyfeiriad e-bost yr anfonwr. Teipiwch gyfeiriad y wefan neu e-bost rydych am ei rheoli ac yna chlicio Rhwystro neu Caniatáu.
+imagepermissionstitle=Eithriadau - Cynnwys Pell
+
+#### Cookies
+cookiepermissionstitle=Eithriadau - Cwcis
+cookiepermissionstext=Gallwch nodi pa wefannau sy'n cael defnyddio cwcis. Teipiwch union gyfeiriad y wefan rydych am ei ganiatáu ac yna cliciwch Rhwystro, Caniatáu am y Sesiwn neu Caniatáu.
+
+#### Cookie Viewer
+hostColon=Gwesteiwr:
+domainColon=Parth:
+forSecureOnly=Cysylltiadau wedi'u hamgryptio'n unig
+forAnyConnection=Unrhyw fath o gysylltiad
+expireAtEndOfSession=Ar ddiwedd sesiwn
+
+noCookieSelected=<heb ddewis cwci>
+cookiesAll=Mae'r cwcis canlynol wedi'u cadw ar eich cyfrifiadur:
+cookiesFiltered=Mae'r cwcis canlynol yn cyd-fynd â'r chwilio:
+# LOCALIZATION NOTE (removeSelectedCookies):
+# Semicolon-separated list of plural forms. See:
+# https://developer.mozilla.org/en/docs/Localization_and_Plurals
+# If you need to display the number of selected elements in your language,
+# you can use #1 in your localization as a placeholder for the number.
+# For example this is the English string with numbers:
+# removeSelectedCookies=Remove #1 Selected;Remove #1 Selected
+removeSelectedCookies=Peidio tynnu'r dewisiadau;Tynnu'r dewis;Tynnu'r dewis;Tynnu'r dewis;Tynnu'r dewis;Tynnu'r dewis
+defaultUserContextLabel=Dim
+
+####Preferences::Advanced::Network
+#LOCALIZATION NOTE: The next string is for the disk usage of the cache.
+# e.g., "Your cache is currently using 200 MB"
+# %1$S = size
+# %2$S = unit (MB, KB, etc.)
+actualDiskCacheSize=Mae eich storfa yn defnyddio %1$S %2$S o le ar ddisg
+actualDiskCacheSizeCalculated=Cyfrifo maint y storfa…
+
+# LOCALIZATION NOTE (labelDefaultFont): %S = font name
+labelDefaultFont=Rhagosodiad (%S)
+labelDefaultFontUnnamed=Rhagosodiad
+
+# LOCALIZATION NOTE (appLocale.label): %S = Name of the application locale,
+# e.g. English (United States)
+appLocale.label=Locale rhaglen: %S
+appLocale.accesskey=r
+# LOCALIZATION NOTE (rsLocale.label): %S = Name of the locale chosen in regional settings,
+# e.g. German (Germany)
+rsLocale.label=Gosodiadau rhanbarthol locale: %S
+rsLocale.accesskey=r
+
+applications-type-pdf = Portable Document Format (PDF)
+
+# LOCALIZATION NOTE (previewInApp): %S = brandShortName
+previewInApp=Rhagolwg yn %S
diff --git a/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/prefs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/prefs.properties
new file mode 100644
index 0000000000..af2482f569
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/prefs.properties
@@ -0,0 +1,90 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# The following are used by the Account Wizard
+#
+enterValidEmail=Rhowch gyfeiriad e-bost dilys.
+accountNameExists=Mae cyfrif gyda'r enw hwnnw'n bodoli eisoes. Rhowch enw arall arno.
+accountNameEmpty=Nid oes modd i enw'r cyfrif fod yn wag.
+modifiedAccountExists=Mae cyfrif gyda'r enw defnyddiwr ac enw gweinydd hynny'n bodoli eisoes. Rhowch enw defnyddiwr a/neu enw gweinydd gwahanol.
+userNameChanged=Mae eich Enw Defnyddiwr wedi'i ddiweddaru. Mae'n bosibl bod angen i chi ddiweddaru'r Cyfeiriad E-bost a/neu Enw Defnyddiwr sy'n gysylltiedig.
+serverNameChanged=Mae gosodiadau enw'r gweinydd wedi newid. Gwiriwch fod unrhyw ffolderi sy'n cael eu defnyddio gan hidlau'n bodoli ar y gweinydd newydd.
+# LOCALIZATION NOTE (junkSettingsBroken): %1$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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/profileDowngrade.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/profileDowngrade.dtd
new file mode 100644
index 0000000000..11186f653d
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/removeAccount.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/removeAccount.dtd
new file mode 100644
index 0000000000..063af3c957
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/removeAccount.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/removeAccount.properties
new file mode 100644
index 0000000000..04d2fbf3aa
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/renameFolderDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/renameFolderDialog.dtd
new file mode 100644
index 0000000000..47beecf007
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/sanitize.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/sanitize.dtd
new file mode 100644
index 0000000000..6c5ff262f9
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 "Y Cyfan">
+<!-- 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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/seamonkeyImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/seamonkeyImportMsgs.properties
new file mode 100644
index 0000000000..806c332e89
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search-attributes.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search-attributes.properties
new file mode 100644
index 0000000000..45e8dd4c52
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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=Enw Dangos
+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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search-operators.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search-operators.properties
new file mode 100644
index 0000000000..f70f751961
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/search.properties
new file mode 100644
index 0000000000..4ce66fa2ed
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/searchTermOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/searchTermOverlay.dtd
new file mode 100644
index 0000000000..6fa4783d85
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/shutdownWindow.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/shutdownWindow.properties
new file mode 100644
index 0000000000..2064a7f58b
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/smime.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/smime.properties
new file mode 100644
index 0000000000..da65e4a0a0
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/smtpEditOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/smtpEditOverlay.dtd
new file mode 100644
index 0000000000..4ccbc1e315
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/subscribe.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/subscribe.dtd
new file mode 100644
index 0000000000..69988a69fa
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/subscribe.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/subscribe.properties
new file mode 100644
index 0000000000..ace52d541b
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/tabmail.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/tabmail.dtd
new file mode 100644
index 0000000000..ee27184cfb
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/taskbar.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/taskbar.properties
new file mode 100644
index 0000000000..21d0132743
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/telemetry.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/telemetry.properties
new file mode 100644
index 0000000000..c736bd9b66
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/templateUtils.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/templateUtils.properties
new file mode 100644
index 0000000000..12e007477c
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/textImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/textImportMsgs.properties
new file mode 100644
index 0000000000..3d827dfe17
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/vCardImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/vCardImportMsgs.properties
new file mode 100644
index 0000000000..2ebcd34088
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewLog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewLog.dtd
new file mode 100644
index 0000000000..05111c4d37
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewSource.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewSource.dtd
new file mode 100644
index 0000000000..6e31177a26
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewSource.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewSource.properties
new file mode 100644
index 0000000000..21c4181eb2
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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 Linell…
+context_goToLine_accesskey = L
+context_wrapLongLines_label = Amlapio Llinellau Hir
+context_highlightSyntax_label = Amlygu Cystrawen
diff --git a/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewZoomOverlay.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/viewZoomOverlay.dtd
new file mode 100644
index 0000000000..f024b9ac6a
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/virtualFolderListDialog.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/virtualFolderListDialog.dtd
new file mode 100644
index 0000000000..88bcc3b76c
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/virtualFolderProperties.dtd b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/virtualFolderProperties.dtd
new file mode 100644
index 0000000000..4ee6e55bc3
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/wmImportMsgs.properties b/thunderbird-l10n/cy/chrome/cy/locale/cy/messenger/wmImportMsgs.properties
new file mode 100644
index 0000000000..649a337245
--- /dev/null
+++ b/thunderbird-l10n/cy/chrome/cy/locale/cy/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.