[Dovecot] Problem with dovecot + imap idle + qmail-localdelivery

[Timo Sirainen]

On Mar 24, 2009, at 3:02 AM, Wouter van der Schagt wrote:

>> Is the problem that mail doesn't actually get deleted when IDLE is   
>> used, or that a client being in IDLE is somehow causing qmail-local  
>> to  give the quota errors incorrectly? I can't see how the latter  
>> would be  possible, IDLE really has nothing to do with quota..
>
> Just a thought...could it be that IDLE prevents a neccessary file  
> handle
> from being released?

There is only one difference between what IDLE does and what a non- 
IDLEing connection does: If inotify/dnotify/kqueue is enabled, Dovecot  
notices immediately when a new mail pops up in new/ or cur/ directory  
and does a resync. Hmm. Actually now I see one possibility if qmail- 
local was written in a stupid/buggy way:

1. qmail-local does rename tmp/file -> new/file
2. Dovecot notices new/file and renames it to cur/file:2, immediately
3. qmail-local stats new/file to see if rename() succeeded (not  
necessary), notices it's no longer there and fails with quota failure  
(..but why quota failure?..)

That's the only explanation I can think of. This could be tested by  
compiling Dovecot with --with-notify=none configure option, which  
would cause IDLE to check for new mails only once in a while and make  
it much less likely to hit the race condition.