Message delivered twice caused by an LMTP error "Got unexpected reply" during upgrade to 2.3

Stephan Bosch stephan at
Thu Aug 16 13:01:59 EEST 2018

Op 16-8-2018 om 11:47 schreef Gabriele Nencioni:
>>>> On 08/09/2018 09:12 AM, Stephan Bosch wrote
>>>>>>> Can you make a pcap log of the LMTP communication between the two
>>>>>>> Dovecot hosts? That may give me a clue on which side of the
>>>>>>> communication is causing the issue.
>>>>>> Yes sure, where I can send it?
>>>>>> Here on list or at your address?
>>>>> Just send it to me.
> On 08/16/2018 10:21 AM, Stephan Bosch wrote:
>> Op 16/08/2018 om 09:46 schreef Gabriele Nencioni:
>>> On 08/15/2018 06:39 PM, Stephan Bosch wrote:
>>>> Op 15-8-2018 om 17:19 schreef Stephan Bosch:
>>>>> Op 13-8-2018 om 15:50 schreef Gabriele Nencioni:
>>>>>> So the scenario seems to be:
>>>>>> the error occurs between old directors and new backends
>>>>>> and between the new backends and the smtp submission_host (for
>>>>>> redirection)
>>>>>> and using the pipeline capability and attaching a file
>>>>>> Let me know if you need more info
>>>>> In this case it is possible to obtain a debug log by enabling
>>>>> mail_debug=yes. Can you obtain a full debug log for such a failing
>>>>> submission session?
>>> Ok! It is attached.
>> That is just weird. Dovecot reports that it cannot fully send the last
>> bits of the message and right thereafter the reply is received, which
>> Dovecot then interprets as out-of-sequence. The PCAP files tell me the
>> final CRLF.CRLF is actually sent to the other side, but somehow Dovecot
>> thinks it couldn't do that yet.
>> Is this problem occurring for any and all SMTP client interactions, or
>> just every once in a while?
> Unfortunately it occurs just every once in a while and it is weird
> because at the second attempt the message is successful delivered or
> redirected.

I have a theory. Will try something later today.

>>>> Also, I don't see anything weird in the PCAP files: the command-reply
>>>> sequence is OK. This means that this is likely a bug in the current
>>>> Dovecot version. Those debug logs should tell me more.
>>> Ok! Which version of dovecot do you suggest to install?
>>> On debian current stable (stretch) repository there is the version
>>> number 2.2.27, have we to install it?
>> If you're facing big trouble it is usually best to revert to the
>> previous version that worked I guess.
> Ok I'm agree!
> So, about you, which version can I try to install the 2.2.27 or the
> previous release of the 2.3 version such as
> v2.3.2 2018-06-29 or
> v2.3.1 2018-02-29?

This would likely happen throughout v2.3.



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