I'm involved with the administration of around a dozen email lists that
run via mailman. They would typically get at least half a dozen
messages a day that were either spam or viruses/worms etc and generate
an email requesting they be dealt with by the individual list admins.
A couple of months ago the main administrator introduced a package
called milter-greylist , which does just what Volker is referring to -
if you're not subscribed, go away and try again in 2 minutes.
Legitimate messages are resent by the ISP and get through next time.
Literally overnight the number of messages that needed to be dealt with
by the administrators went from several a day to zero and I've not seen
an admin notice from any of the lists for weeks now.
Absolutely magic :-))
http://hcpnet.free.fr/milter-greylist/
and plenty of hits in google.
Cheers,
Roger
Volker Kuhlmann wrote:
Greylisting mail is completely pointless, due to all of the methods
having been published in great detail.
I'm not sure that reasoning holds. Rejecting all email from senders
which haven't sent anything before with a "service unavailable, try
again in X minutes" is, theoretical anyway, covered by the mail
transport protocol. Obviously this won't get rid of spammers who in fact
do try again in X minutes, but it does get rid of rubbish from worms etc
which lack more sophisticated retry mechanisms. It also gets rid of the
vast majority of spammers who don't bother to retry. I'd expect that to
change though as soon as it's making a noticable dent into the spammers'
success. Still more time for the filters to catch up...
Volker
