[Dovecot] Why is "UIDVALIDITY changed" fatal?

[Chris Wakelin]

Todd Burroughs wrote:
> I have this problem as well, but I don't think that it is UW doing it in
> my case.  If I switch my mailbox back and forth, I don't see the problem.

I think it happens when a large number of messages are added or removed. 
E.g. the prune script I mentioned will delete all messages older than a 
week, which could be a lot in the case of my Spam folder ;-)

It's not clear to me (yet) why UW-IMAP needs to change UIDVALIDITY; it's 
usually just the output of time(0) and I don't think it should be 
running out of UIDs (a 32-bit number!) for the messages. My guess is the 
X-IMAPbase header, where UIDVALIDITY is stored, is disappearing somehow.

> The most common case here is some of our support mailboxes where several
> people log into them at once (I know, they shouldn't...).  This causes
> all sorts of these errors, but dovecot recovers from them and the support
> staff doesn't seem to notice.  Also, the mbox hasn't become corrupted
> so far, which is a really good thing.
> 
> Maybe your users are doing the same thing?

Don't think so. I've been testing multiple accesses to my INBOX with 
only transient problems due to clients caching stuff. I don't think my 
colleagues have been doing so, though.

I should also say it's mboxes, Dovecot-1.0-stable, and local disk 
(maildirs over NFS are in the future, possibly!).

Best Wishes,
Chris

-- 
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Christopher Wakelin,                           c.d.wakelin at reading.ac.uk
IT Services Centre, The University of Reading,  Tel: +44 (0)118 378 8439
Whiteknights, Reading, RG6 2AF, UK              Fax: +44 (0)118 975 3094