On 2021-07-15 at 08:25:41 UTC-0400 (Thu, 15 Jul 2021 05:25:41 -0700) Greg Earle <mailmate@lists.freron.com> is rumored to have said:
tl;dr: Where do MailMate/Apple Mail store the flag color info for each message?
All on the server, in IMAP flags/keywords: \Flagged, $MailFlagBit0, $MailFlagBit1, and $MailFlagBit2
Standard IMAP flags in a Maildir mailbox are stored as a string of characters sorted in ASCII order (all capitals before lowercase) at the end of the filename, delimited by a comma. Both Courier and Dovecot use the capital letters DFRST for the \Draft, \Flagged, \Answered (i.e. Replied), \Seen, and \Deleted (i.e. Trashed) flags. The original Maildir spec also defines a
Courier stores arbitrary additional keywords (non-standard flags) in a subdirectory named courierimapkeywords with a master list of keywords and a file for each message that has any keywords set.
Dovecot maintains a dovecot-keywords file in each Maildir mapping any additional keywords to lowercase letters (perversely by numbering them in the file so that keyword '0' is indicated by 'a' in the filename tail.) If you use more than 26 unique keywords in a single mailbox in Dovecot, it falls back to storing the 27th and later ones in its binary index files in the Maildir.
So to convert a Courier Maildir to a Dovecot Maildir while preserving flags, you would need to do more than rsync them. You would also need something that translates the contents of courierimapkeywords into additional characters at the end of message files and a dovecot-keywords file.
-- Bill Cole b...@scconsult.com or billc...@apache.org (AKA @grumpybozo and many *@billmail.scconsult.com addresses) Not Currently Available For Hire _______________________________________________ mailmate mailing list mailmate@lists.freron.com https://lists.freron.com/listinfo/mailmate
