[Asrg] where the message originated

[Paul Russell]

On 1/14/2009 8:00 AM, David Wilson wrote:
> 
> After all, if the "MTA" from which you received the infected message is
> not innocent, perhaps not even a proper MTA, then rejecting the message
> is also pointless. The rejection will be ignored, and so the overall
> effect will be the same as if it were accepted and discarded.

If I understand your position correctly, you want the receiving MTA to issue a
5xx when the sender is a real mail server, but you want it to accept and discard
the message when the sender is a bot.  As has already been pointed out, for
systems outside your control, you can only speculate as to their true nature and
their likely reaction of a 5xx response.  Why waste time trying to discern the
true nature of the sender, and run the risk that you will discard messages which
should have been rejected, because your analysis of the sender is imperfect?
Just issue the 5xx and be done with it.

-- 
Paul Russell, Senior Systems Administrator
OIT Messaging Services Team
University of Notre Dame
prussell at nd.edu