[Dovecot] Outlook 2007 & 2010 hangs in v2.2?

Timo Sirainen tss at iki.fi
Mon Jun 9 20:12:42 UTC 2014

On 9.6.2014, at 20.49, Andy Dills <andy at xecu.net> wrote:

>>> Has anybody noticed Outlook 2007 & 2010 (but apparently not 2013) hanging IMAP connections with Dovecot v2.2 (but not v2.1) when they're FETCHing large mails? I can't think of any reasonable explanation for this.
>> Most likely solved by: http://hg.dovecot.org/dovecot-2.2/rev/6a9508d28d34 [1]
>> Strange that it didn't break more commonly or that more people weren't complaining about it.. The bug has been there since v2.2.7.
> Thank you Timo. This patch did indeed correct the problem, we had no
> problem doing full syncs with the problematic accounts after
> implementing this. 
> Is it perhaps something that only happens with directory/proxy
> environments? I'm surprised it hasn't been mentioned before, I figured
> it was something particular to our implementation since nobody else was
> mentioning it, until you did. 
> Fascinating to me that it only affects Outlook as well. I don't
> understand the code well enough to grasp the impact of the bug, so if
> somebody has a minute to share an explanation that would be cool. 

Only happened when using Dovecot proxy. Only happened if client sent a command while another long running command was already sending data. So basically if Outlook started downloading a large mail on background and user clicked another mail, the already running FETCH was stopped because Outlook sent another FETCH command to the same connection. I guess Outlook was the only client to do that.

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