In <8405(_dot_)1049662670(_at_)kanga(_dot_)nu> J C Lawrence
<claw(_at_)kanga(_dot_)nu> writes:
Filtering returning bounces based on Message-ID requires that the MX
keep a DB of known-valid IDs. This is a non-trivial expense.
I believe that the expense is usually trivial compared with the cost
of the time that spam places on the human. There are a lot of people
who seem to be penny wise and pound foolish about spam.
I'm not saying that every technique used to reduce spam is worth
whatever costs may be needed to implement it in any given situation.
However, if you find that many of the techniques are costly because of
how you have designed your mail system, you may be better off
rethinking how your mail system is designed.
-wayne
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