[Dovecot] Mailbox locking issue?

[Timo Sirainen]

On Fri, 2008-04-11 at 22:52 -0700, Mark Sapiro wrote:
> Apr  8 19:07:20 sbh16 dovecot: pop3-login: Login: user=<xxx>,
> method=PLAIN, rip=72.52.113.36, lip=72.52.113.36, secured

Dovecot read-locks the mbox file here.

> Apr  8 19:07:22 sbh16 postfix/local[13745]: D959169046B:
> to=xxx at example.com>, orig_to=<xxx at example.org>, relay=local,
> delay=16, delays=15/0/0/1.1, dsn=2.0.0, status=sent (delivered to
> mailbox)
> Apr  8 19:07:22 sbh16 dovecot: POP3(xxx): Disconnected: Logged out
> top=2/15995, retr=0/0, del=2/2, size=15985

These both happen within the same second, so most likely Postfix
correctly waits that Doveocot has finished modifying the mbox file and
only then delivers its changes.

> Five minutes later when fetchmail comes back, we see
> 
> Apr  8 19:12:42 sbh16 dovecot: POP3(xxx): mbox sync: Expunged message
> reappeared in mailbox /var/spool/mail/xxx (UID 4683 < 4684, seq=2,
> idx_msgs=0)

seq=2 would indicate that there are now two mails, but there should have
been only one now.. I tried this a couple of times myself, but it worked
in my tests. I'm using v1.0.13 though, so there's also a chance this has
been fixed already.

> From now on, as messages are added to the mailbox by Postfix, fetchmail
> keeps retrieving both old and new messages. i.e. even though dovecot's
> log says del 1/1 (or del n/n) no messages are actually deleted from
> the mailbox.
> 
> This situation continues until someone accesses the mailbox locally
> (e.g. via mutt through a local shell) and deletes the old messages.

When this happens, could you put the mbox file through
http://dovecot.org/tools/mbox-anonymize.pl and send the result to me,
along with dovecot.index and dovecot.index.log files.

> Also it seems that dovecot should recover from the 'corrupt' mailbox
> and fix it rather than just continuing to encounter the same problem.

Yes, it shold.
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