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Date:      Sun, 29 Dec 2002 12:06:42 -0600
From:      Len Conrad <>
Subject:   Re: What are the SMTP rules for sending mail to FreeBSD
Message-ID:  <>
In-Reply-To: <>
References:  <> <> <>

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>ISTR Postfix replies with 450 to (almost) all errors by default.

And there are errors where you need to escalate the 4xx response to 554 to 
stop the sending MTA from re-trying for days, or just harvest the 4xx ip's 
to a new .map filean block with 554.

Postfix's new "sender address verification" is extremely effective in 
blocking crap that used to get through, but it always returns 4xx so your 
reject counts go through the roof as SAV 4xx rejects are re-tried 100's of 
times.  But, in fact, this is more of a resource consumption for the 
senders than it is on your MX.  And the advantage of keeping this crap out 
of your system outweighs the higher rate of repeated rejects.


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