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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 09:51:24 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-28 09:51:24 +0000 |
commit | f7548d6d28c313cf80e6f3ef89aed16a19815df1 (patch) | |
tree | a3f6f2a3f247293bee59ecd28e8cd8ceb6ca064a /doc/wiki/MailboxFormat.MH.txt | |
parent | Initial commit. (diff) | |
download | dovecot-f7548d6d28c313cf80e6f3ef89aed16a19815df1.tar.xz dovecot-f7548d6d28c313cf80e6f3ef89aed16a19815df1.zip |
Adding upstream version 1:2.3.19.1+dfsg1.upstream/1%2.3.19.1+dfsg1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/wiki/MailboxFormat.MH.txt')
-rw-r--r-- | doc/wiki/MailboxFormat.MH.txt | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/doc/wiki/MailboxFormat.MH.txt b/doc/wiki/MailboxFormat.MH.txt new file mode 100644 index 0000000..cbe7190 --- /dev/null +++ b/doc/wiki/MailboxFormat.MH.txt @@ -0,0 +1,52 @@ +MH Mailbox Format +================= + +The MH mailbox format originated with a system developed by the RAND +corporation and the University of California. Each email message is stored in +a single file, with directories indicating folders and subfolders. The index +or order of the messages in the folder determine what each message is named +(which may not correspond to the inode index). The "safe" way to guarantee a +message gets written to a mail folder is to first write the message out to a +randomly chosen temporary file name, then link the file to the number LAST+1, +where LAST is the last sequential message in the folder. If the link fails, +increment the counter and try again. + +MH folders also maintains a meta-file called '~/Mail/.mh_context' that contains +information about the most current folder and message chosen. Each sub-folder +also contains a meta-file called '.mh_sequences' or '.xmhcache', which +maintains keyword association lists for stored queries. New messages are +stored in the "unseen" sequence for a folder. Procmail itself does not bother +making changes to this file, rather simply delivers the message to the folder +and leaves determining new messages as an exercise for the MUA. For example: + +---%<------------------------------------------------------------------------- +unseen: 1-3 8 15 +projectB: 2-8 10 +---%<------------------------------------------------------------------------- + +shows two stored sequences of messages. Command-line utilities can then use +these sequences as shortcuts.'show unseen', for example, is short-hand for +'show 1-3 8 15'. + +Deleted emails are indicated by prepending a "," to the name. One of the +largest problems that IMAP servers have with MH format is the volatility of the +email message name itself. The command-line utility 'sortm' is used to sort +mail folders by date or string matching. To do this, messages are actually +renamed to reflect the new sort order. IMAP servers are required to maintain +an index of the folder contents, so when the names of the file entries cannot +be guaranteed to be stable, IMAP servers have to throw out previous index +caches and re-index. + +When operating with a shell account on a machine that also provides IMAP access +to folders, users are encouraged not to re-sort email locally while accessing +the IMAP server remotely. + +Links + + * NMH [http://www.nongnu.org/nmh/]: New MH Client + * Original RAND MH [http://rand-mh.sourceforge.net] Code + * MH-Book [http://rand-mh.sourceforge.net/book/] + * Mutt Manual [http://www.mutt.org/doc/manual/manual-4.html#ss4.6]: Describing + how it handles MH folders + +(This file was created from the wiki on 2019-06-19 12:42) |