From: Rocco Scappatura (Rocco.Scappaturainfracom.it)
Date: Thu Feb 07 2008 - 04:02:57 CST

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> Rocco Scappatura wrote:
>>
>> I've tried to debug the SMTP communication with tcpdump. And I saw many
>> TCP retransmission. It could be a problem?
>>
>
> Yes, that's likely the problem. Your new machine has a bad
> network card or bad network driver or bad network config, or
> traverses through a hub, switch or router that is dropping
> packets. This is not a postfix problem.
>

Infact, between the Postfix and the MS Exchange machines there is a
firewall. On its log I see that every SMTP packet is blocked. The
explanation for the problem detected by the firewall is:

"ASQ analyses check that packet headers comply with the data contained in
the packets. In this way, ASQ offers effective protection against network
layer attacks up to the application layer. A datatracking module enables,
among other things, saving data for later analysis of the packet."

Indeed, is not easy form me to catch the cause of the trouble.. I will
investigate..

Thanks,

rocsca

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