[Dovecot] UID inserted in the middle of mailbox errors

[Dean Brooks]

Hi,

We are still getting, on a daily basis, users who cannot move messages
to Trash or expunge Trash due to these errors:

   Mar 28 10:43:57 tm2 dovecot: [ID 107833 mail.error] IMAP(kss021):
   mbox sync: UID inserted in the middle of mailbox
   /home/kss021/Mail/Trash (3137 > 536, seq=2, idx_msgs=76)

Our users have no other access to their mailbox other than Dovecot,
and we are using mbox format and 1.1rc3.

Deleting the indexes fixes the problem, so it seems to be a problem
with index corruption and not something inherently wrong with the
mailbox.  That is, once I delete the index files, the problem does not
come back immediately.

I've seen others on the list with the same problem, but I wasn't able
to find a workaround.  It's happening more and more frequently.

I guess what I don't understand is why Dovecot cant just mark the index
invalid and purge it instead of failing over and over.  I thought the
whole point behind Dovecot's indexing is that it was able to detect
index inconsistencies and mark the index invalid.

Any help is much appreciated.  Even a quick stopgap fix would be
a lifesaver, short of a cronjob that just purges everyone's index
files every 2 hours (which sort of defeats the point of using Dovecot).

--
Dean Brooks
dean at iglou.com