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> Hello Colleagues,
>
> on the one of our SMTP servers we are receiving a lot of duplicate messages
> with different time stamp and ID. The same message(with the same content)
> is received at : 11:20, 13:50, 16:30.
>
> What could be a reason for it ? Could it be a problem with Postfix server
> on the our client side ? For example, our client Postfix server wasn't able
> to send message first time but for some reason our server received message.
> And then after two hours its tried to sent the same message again... and
> again.
>
>
> What could be a reason of duplicate messages received in the different time
> stamps ?
See RFC 1047, "DUPLICATE MESSAGES AND SMTP", published in 1988.
This can happen when the sender times out before the receiver
responds to "end-of-data". For example, the sender has too short
timeouts, or the receiver is too slow (too many header/body_checks
in Postfix, or too many DNS lookups in content filter).
Wietse
