On Wed, 31 Mar 2004 19:21:43 EST, "Douglas F. Calvert" <douglist@anize.org> said:
justification for this practice? In my opinion it does not appear to increase the validity of the connection. But I may be missing something
It tells you that the connection is coming from a netblock managed by somebody with enough clue and motivation to get PTR records right. If the site can't even get that right, they're probably lacking in logging/auditing and the like as well. As a result, it's a pretty safe bet that if your site policy says you'll go looking for somebody if there's a problem with the connection, you might as well drop the connection early on, because nobody's answering the cluephone at the remote end... As far as SMTP goes, it's surprising (barely) how often you get "MX points to myself" errors back from sites that don't have a valid PTR either....