> As someone has probably already pointed out... admins use these
> lists because they trust their accuracy. If they receive too
> many complaints (as we did with a particular DNSBL) you stop
> blocking on that list and move to only scoring.
No, you move on to greylisting based on the less accurate DNSBLs.
milter-greylist 3.0rc6 supports DNSBL-based greylisting, and it works a
treat here. Because it is greylisting and not blacklisting, no
legitimate mail gets blocked.
If you use short greylisting periods legitimate emails should get
through on the second attempt.
dul.dnsbl.sorbs.net, bl.spamcop.net, dynablock.njabl.org, and
psbl.surriel.com are all useful.
spamcop's apparent false positive rate here is under 1.5%, psbl's 0.25%.
We've currently got 49117 records ("ip, from, to" triples) in
greylist.db, of which only 1204 are whitelisted, so it is worthwhile to
greylist.
Cheers,
Phil
--
Phil Randal
Network Engineer
Herefordshire Council
Hereford, UK
