hi list,
i'm in the process of testing dovecot before a hopeful switchover from uw-imap/qpopper to dovecot, primarily to get off of the uw-imap/mbox combo and moved to Maildir. i think we've worked out the logistics to avoid any service downtime, with only a short window of a few minutes per user for when we convert from mbox to maildir format.
however, during testing a few issues have come up, some of which i've been able to work around, others which i haven't. for those that i have been able to work around, i'll include my solution so that fellow googlers may profit, and for those that i haven't i'd really appreciate your feedback.
logistical problems:
1 - automagic detection and uw-imap inbox in ~/mbox. i'm not sure if this is a default characteristic or if it's specific to us, but our spool is in /var/mail/foo and inbox in ~/mbox. the automagic Maildir/mbox detection doesn't find the "mbox", and i can't tell it where it is because then it doesn't look for the Maildir. solution: i wrote a small patch to dovecot's autodetect code to help it find the location of our mailboxes. if anyone would like a copy of said patch i can send it off list.
2 - uw-imap's spool/inbox message moving. i read from the wiki that this isn't a feature currently being worked on. solution: deliver all mail to the same place. since we use procmail as our MDA, this isn't too hard of a problem. basically we redirect mail to the inbox and redeliver everything in the spool.
3 - supporting multi-homed services + ssl. for historical reasons we provide services from multiple hostnames (mail.foo, imap.foo, etc). with ssl, that means a different cert for each, otherwise some clients will break. solution: we're spawning off three seperate dovecot instances, each using a different config file. not the most graceful, but it works...
application problems:
4 - dovecot imap + ms lookout 2002 + deleting messages. i'm not sure if this is an app or server side problem. basically, a user will delete a message, only to have it reappear in the mailbox a short time (few minutes) later. if i monitor the state of the mbox file, no changes are made to it until the user selects "empty trash", after which point they are expunged. looking at a protocol dump, i see the client setting the deleted flag on the message when they originally delete it. here's an excerpt:
<snip> tg7i OK Idle completed.
6gzd UID STORE 30021 +FLAGS (\Deleted \Seen)
- 51 FETCH (FLAGS (\Deleted \Seen \Recent) UID 30021) 6gzd OK Store completed.
stpw IDLE <snip>
i'm not too familiar with imap, but it looks like the server is
caching the deletion request and then forgetting later forgetting
about it? i have all the "client workarounds" enabled, fwiw.solution: ???
5 - mac os x + eudora + deleting mail. a different problem alltogether. in eudora deleting a mail seems to immediately move it to the "trash" mailbox, so the above problem does not occur. what *does* happen is that if a user rapidly deletes messages one-by-one, an error message pops up about UID's not existing. i haven't gotten a full description of this problem, but here's an excerpt from what i think is the symptom:
<snip> A00109 UID COPY 30002 Trash
A00109 OK Copy completed.
A00110 UID STORE 30002 +Flags.silent (\Deleted)
A00110 OK Store completed.
A00111 EXPUNGE
- 31 EXPUNGE A00111 OK Expunge completed. <snip> and later: <snip> A00040 UID FETCH 30002 (UID BODYSTRUCTURE)
A00040 NO Some of the requested messages no longer exist.
A00041 UID FETCH 30002 RFC822.SIZE
A00041 NO Some of the requested messages no longer exist.
A00042 UID FETCH 30002 (BODY.PEEK[])
A00042 NO Some of the requested messages no longer exist. <snip> which i suppose is correct that it doesn't exist (since it was moved out of the inbox). however, eudora does not have this problem with uw-imap, and i'm wondering what might be causing it? solution: ???
okay, i think that's everything that i've ran into. we're still pushing ahead with this because we need to get the hell off of uw-imap/mbox, but i don't think we'll be able to stick with dovecot if these are unresolvable issues. in that case, we'll probably use dovecot with these minor nuisances while we transition, and then perhaps use courier in the long run. hopefully that won't have to be the case though :)
if anyone has any experience specifically with "5" and "5", i'd really, really like to hear about it. in the meantime, i'll continue to test other things, and also see if the problem also persists when mail is stored in Maildir format.
anyway, thanks for your time! sean