[OT] Spam filtering (was Re: [Imap-uw] Outlook deadlock)
uwimap at phroggy.com
Thu Sep 20 12:44:15 PDT 2007
> I only use sbl-xbl.spamhaus.org and list.dsbl.org. Had to drop the
> dial-up blacklist due to too many complaints about false positives.
> Some ISP's seem to use dial-up numbers as fixed IP for business dsl.
I use those too. I also catch a small handful with
web.dnsbl.sorbs.net, and I block China and Korea with
cn.ascc.dnsbl.bit.nl and korea.services.net respectively. The idea
of blocking entire countries bothers me, but I've had no false
positives yet (the only person I know in Korea uses Yahoo Mail).
I also use home-grown substring and regex lists, matched against
either the reverse DNS hostname or the HELO string (if HELO is a
valid hostname that resolves to their actual IP I'll trust it,
otherwise I use reverse DNS regardless of whether it resolves back to
anything). I skip these tests for authenticated users who are
relaying mail. These lists are designed to match dynamic IPs, but
because they're based on hostname rather than IP and I trust valid
HELO strings, I avoid blocking properly-configured mail servers that
happen to be on residential ISPs.
If anyone's interested in my list, I'd be happy to share.
More information about the Imap-uw