Op 16-8-2018 om 11:47 schreef Gabriele Nencioni:

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On 08/09/2018 09:12 AM, Stephan Bosch wrote

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> 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.

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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.

Regards,

Stephan.