Nathaniel Borenstein wrote:
As usual I agree with Mr. EEF:
On Aug 9, 2010, at 10:27 PM, ned+ietf-smtp(_at_)mrochek(_dot_)com wrote:
I have a somewhat different take on this. First of all, I have always thought
the admonition that you MUST minimize the amount of time spent before
responding to the trailing dot to the greatest extent possible was, well, bunk.
(It's also an effectively unenforceable MUST - who can say you've done all you
can or not? - which is bad in its own right.) While it is important not to
spend too much time, the difference between a millisecond delay and a 2 second
delay is, in this situation, not worth worrying about.
Rejecting anything that you can at the SMTP level, rather than generating a bounce,
strikes me as a sufficiently Good Thing that it outweighs any remaining benefits from the
"MUST minimize" rule. Minimizing bounces seems more valuable than minimizing
SMTP connection time, primarily because the bounces are more likely to waste an actual
human being's time at some later point. -- Nathaniel
Agree with this, but I still don't run my spam filters before the final
ACCEPT. As long as there is a possibility that the filter will take too
long, it isn't worth the confusion resulting from a timeout.
I have a small system, and my setup may be different for that reason,
but I'm just not seeing the need for anything as laborious as
statistical filtering during the SMTP session. Heavily abused IPs get
an immediate REJECT. Of the remainder, most legitimate messages get
whitelisted, based on the reputation of the domain name extracted from
their HELO name. That leaves a small slice in the middle that gets an
ACCEPT, but then goes through the spam filter and to quarantine. Less
than 1 in 1000 spams in my inbox, and no false rejects.
Am I the only one using the HELO name for whitelisting?
--
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