Robert Fournerat put forth on 8/19/2010 4:46 PM: > Quoting Noel Jones <[email protected]>: > >> Same here. reject_unknown_client_hostname is too strict, but >> reject_unknown_reverse_client_hostname rejects lots of obvious spambots >> without resorting to an RBL lookup. The false-positive rate is close >> enough to zero that I would not consider removing this restriction. > > Call me a BOFH, but I have no sympathy for mail servers > that do not pass the FCRDNS test.
Agreed. Given that the majority of consumer broadband providers in the US assign rDNS to even all their consumer IP addresses, there's no reason for a legit mail sending host to not have rDNS. However, because of the above situation, the existence of rDNS for a mail sending host is worth less as a spam check because so many devices have rDNS today. Using fully qualified regular expressions to check for such consumer space rDNS is usually much more effective and less error prone. The Enemies List has the largest collection of such expressions matching the largest swatch of consumer (i.e. zombie) rDNS strings on the planet: http://enemieslist.com/ Unfortunately it's not free or publicly available. -- Stan
