dnsbl'S + bogofilter = spam barbecue

[Jef Poskanzer]

>I returned to DNSBLs because they are so computationally cheap
>it seemed like a shame to not use them, but how to use them in
>a way that gives them a vote, not a veto?

Actually, that sounds pretty easy to me: just have your dnsbl
processor add a header to the message listing the dnsbls it
failed.  Then bogofilter will automatically learn which ones
to trust.

Oh, I guess the problem with that is no one runs bogofilter at SMTP
time, so you'd lose the main advantage of the dnsbl, instant rejection.
Well, I'm working on a nice fast C bogomilter, so this should become
practical soon.

And I'd say they are cheap to run but not ultimately cheap.  If a dnsbl
is having DNS problems, then your mail handling slows down.  This means
you have more mail processes hanging around waiting, which uses up memory.
I see this effect with my spfmilter, which also relies on other people's
DNS records.

For extremely fast/cheap SMTP-time rejection, I use blackmilter
with my own locally-derived blacklists and whitelists.
---
Jef

         Jef Poskanzer  jef at acme.com  http://www.acme.com/jef/