-----Original Message-----
From: asrg-bounces(_at_)ietf(_dot_)org
[mailto:asrg-bounces(_at_)ietf(_dot_)org] On Behalf Of Bill
Cole
Sent: Tuesday, April 12, 2005 6:13 PM
To: asrg(_at_)ietf(_dot_)org
Subject: RE: [Asrg] article: port 25 blocking
[SNIP]
Not at all. The present is reasonably good and the future is fairly bright.
The exceptions to that are for people who want a single magic bullet for
spam control, and particularly for people who want that magic bullet to be
their own patented idea. It is possible right now to achieve 95% spam
rejection before DATA in SMTP and 99% rejection overall, with less than
0.01% false positives. The constraints in which that can be done are not
economically feasible for large ISP's and might not even be possible for
their sorts of very large and very diverse mail domains.
Looking at the problem as one addressed by SPF *or* port 25 blocking *or*
some other approach is a hopeless approach. SPF and port 25 blocking both
can help solve certain problems related to spam, but neither is anywhere
near a full solution. There is a huge set of tactics and tools out there
right now that can be applied carefully, selectively, and *jointly* in
different situations to achieve very good results. The 'spam problem' is not
that no one knows how to avoid spam, but rather that too few people are
willing to devote the needed resources to avoiding it and making sure they
don't contribute to it. SPF helps on one side by letting some domains
publish hints of mixed value as to the validity of mail claiming to be them.
Port 25 blocking of dynamically assigned address space aids on another front
by reducing the population of useful spam zombies.
Bill, although I really hate the idea of port blocking, you make some very
persuasive arguments. Sorry about the bad quoting, it's this stupid client
software of mine.
George
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