[Dovecot] Dovecot proxy to Microsoft Exchange 2013

Charles Marcus CMarcus at Media-Brokers.com
Tue Jun 25 14:24:40 EEST 2013

I'm wondering if this could have anything to do with how Exchange 2013 
broke recipient verification?

Discussed recently on the postfix list:


In that thread there is this link to a Technet discussion:


On 2013-06-25 6:52 AM, Timo Sirainen <tss at iki.fi> wrote:
> On 25.6.2013, at 13.36, Jerry <jerry at seibercom.net> wrote:
>> On Mon, 24 Jun 2013 23:40:57 +0300
>> Timo Sirainen articulated:
>>> Looks like Exchange 2013 IMAP has broken command pipelining :( See if
>>> it gets fixed by http://hg.dovecot.org/dovecot-2.2/rev/6e8bbc150fa9
>>> and the attached patch on top of that? If it works, I'll commit that
>>> patch too.
>> Timo, I have not really been following this thread very closely, so I
>> am not quite sure what the problem is exactly. I have a friend who has
>> a friend who has input on Microsoft Exchange development. If you could
>> supply me, perhaps off list if you desire, specifics of exactly what
>> you believe Microsoft Exchange 2013 is doing incorrectly, I could
>> forward this information on. You would need to be quite specific
>> though. Generalizations would not be of any use.
> Looking at the first mail in this thread, it looks like when Dovecot sends within one TCP packet:
> L LOGIN "user at domain.com.br" "123456"
> Exchange replies only to the CAPABILITY command with:
> C OK CAPABILITY completed.
> Then the session gets stuck, because Dovecot doesn't send anything, only expects Exchange to also handle the LOGIN command, but it's not doing that, most likely because it didn't think that two commands could be within a single TCP packet.


Best regards,

Charles Marcus
I.T. Director
Media Brokers International, Inc.
678.514.6224 | 678.514.6299 fax

More information about the dovecot mailing list