Re: Processing after the end of DATA
2010-08-10 13:38:40
Carl S. Gutekunst wrote:
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.
Almost all of the commercial enterprise-grade filters I know do *all*
of their filtering before accept: spam, virus, content policies, etc.
That's because of the desire to emit a clear rejection, and
backscatter is a far more serious problem than duplicates. The
exceptions (those that do filtering after the 250 OK) don't generate
DSNs; they deliver to a spam folder or other quarantine.
<csg>
My system is too small to draw any conclusions, but my impression is
that we are overly-concerned about a very small fraction of the mailflow
- those few messages that are legit, but get a false reject from a
statistical filter. We really don't care about the proper SMTP response
if it is spam. The only advantage I see in running the spam filter
before ACCEPT is a few less messages at the bottom of my spam bucket. I
wish I had some numbers from a larger system.
Would be nice if SMTP had a 'conditional ACCEPT': "Sorry, your
transmitter ID 'yahoo.com' cannot be verified, Your message has been
routed to the recipient's quarantine." Imagine the effect that would
have on all the lame excuses for an invalid or hard-to-verify HELO name.
--
************************************************************ *
* David MacQuigg, PhD email: macquigg at ece.arizona.edu * *
* Research Associate phone: USA 520-721-4583 * * *
* ECE Department, University of Arizona * * *
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- Re: Processing after the end of DATA, (continued)
- Re: Processing after the end of DATA, SM
- Re: Processing after the end of DATA, Nathaniel Borenstein
- Re: Processing after the end of DATA, David MacQuigg
- Re: Processing after the end of DATA, Carl S. Gutekunst
- Re: Processing after the end of DATA,
David MacQuigg <=
- Re: Processing after the end of DATA, John Levine
- Re: Processing after the end of DATA, David MacQuigg
- Re: Processing after the end of DATA, Дилян Палаузов
- Re: Processing after the end of DATA, David MacQuigg
- Re: per user post-data rejects, Processing after the end of DATA, Дилян Палаузов
- Re: per user post-data rejects, Processing after the end of DATA, David MacQuigg
- Re: per user post-data rejects, Processing after the end of DATA, Дилян Палаузов
- Re: Processing after the end of DATA, ned+ietf-smtp
- Re: per user post-data rejects, Processing after the end of DATA, John Levine
- Re: per user post-data rejects, Processing after the end of DATA, ned+ietf-smtp
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