"Mark A. Lewis" mark@siliconjunkie.net writes:
Lets say that Acme Widget has their mail hosted with Hostco. Acme Widget would rather not have mail.hostco.com in the mail headers for whatever reason. So, hostco doesn't setup a ptr record for it. This does not make Acme Widget or Hostco any more likely to be spammers, it just makes you more likely to drop their mail.
Actually, the problem you're describing is routinely solved at any decent ISP *without* breaking any rules. If the above were a genuine scenario, I would conclude that Hostco is run by nincompoops. ;-)
-tih