[Techtalk] Spam solutions
qirien at icecavern.net
Sat Aug 21 09:15:09 EST 2004
> Right now I'm ready to try the Bayesian filters, but I haven't had much
> experience with them and I've read several people say that spamassassin's
> Bayesian filtering isn't great.
I've had pretty good luck with spamassassin's Bayesian filtering, but I do
still have to scan through my Spam folder and make sure there weren't any
errors. Before we implemented greylisting, this was a pretty big pain. Most
of the messages that it got wrong were from non-technical friends who tended
to not use capitalization or send chain letters or things like that. But
it's gotten better with training (probably partly because of the
auto-whitelisting feature, where it remembers the From on messages you mark
With greylisting, the amount of spam that gets through is so small that it's
been trivial to check the spam folder for false positives. We're using
postfix with a daemon called GLD (http://www.gasmi.net/gld.html). There are
several other implementations, however, that you can see at
I would definitely not recommend whitelisting -- it's a huge pain for anyone
writing you e-mail (especially with mailing lists and things like that), and
a huge pain for you as you have to manually add addresses you really want to
get mail from (for example, when shopping online, you may not know what
address they'll send your receipt from, and if it's automated, they might not
reply to get on your whitelist). The only time I could really see it being
worth it is with a child or someone who just gets e-mail from a few people
and doesn't do any online shopping or mailing lists.
Greylisting would work fine with whitelisting, as long as the
challenge-response is sent via valid SMTP. Basically all greylisting does is
say "send that to me later". Spammers give up because the programs they use
to send spam don't follow valid SMTP protocol. Legitimate mail servers do
follow protocol, and when they retry the message, you let them through. See
http://www.greylisting.org for more information.
Hope this helps!
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