David F. Skoll said:
On Tue, 4 Mar 2003, Justin Mason wrote:
One issue BTW that filter-during-SMTP-transaction systems have to think
about, is that if you teergrube or tempfail on an entire ESMTP connection
basis, this could result in affecting legit mail
We do it on a per-message basis. We only use tempfail codes; we don't
attempt to tarpit. Tarpitting can open your machine up to DoS attacks,
because even a tarpitted process consumes some resources on your end.
As a matter of interest, have you collected any stats on the effectiveness
of tempfailing suspected spam? I hear it's very effective at blocking
spam from spamware which doesn't support requeue-and-retry, but I have
no idea how effective "very" is. ;)
Yes, sometimes legit mail is held up, but thanks to the fine authors
of SpamAssassin :-), that doesn't happen too often.
Cheers! ;)
--j.
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