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Today i noticed the following in my postfix logs:

I got this in logs:

Mar  6 13:36:16 my_server_name postfix/smtpd[23482]: connect from <other_server_IP>
Mar  6 13:36:16 my_server_name postfix/smtpd[23482]: 0672758002: client=unknown <other_server_IP>

following this message in logs, I found this 5 minutes late:

Mar  6 13:41:16 my_server_name postfix/smtpd[23482]: timeout after DATA (478 bytes) from unknown[other_server_ip]
Mar  6 13:41:16 my_server_name postfix/smtpd[23482]: disconnect from unknown[other_server_IP]
Mar  6 13:41:16 my_server_name postfix/cleanup[25740]: 0672758002: message-id=<358106663.93.1394109376020.JavaMail.apwbcprd@my_server_ip>

Then no more entries.

The other server is sending messages via java code. This other server has other success attempts and other failed attempts due to network. At the same time my SMTP server was handling other requests successfully.

I assume that there is an issue in the other server, so that my SMTP server didn't receive rest of message so that we can't see qmdr, pickup, pipe and so on.

NOTE: running mailq command, I don't have messages in the queue

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I found the solution, it's in the MTU size :) .. – DeepoOoOoz Mar 6 '14 at 20:09

added solution from OP comment

Looks like adjusting the MTU size fixes the problem.

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