Stan Hoeppner wrote:
Rejecting mail due to lack of a PTR is an anti bot spam tactic. It is as prevalent today as it was 5 years ago, but probably less effective. Many ISPs went PTR crazy, assigning them to all their dynamic consumer IP ranges. DULs and generic PTR regexes are now more effective in this regard. Even so, there are still large amounts of consumer IP space without PTRs, so this tactic is still valid, and still widely used.
The problem is that in countries under developpement (e.g. in Africa), there are lots of legitimate mail servers who aren't well administered (accordingly with our "best practices"). So rejecting messages coming from servers without PTR is a way to reject communications with these countries. It's okay if don't communicate with people from these countries.
JM
