On Mon, 1 Dec 2003, Steven M. Bellovin wrote:
Right. Assuming that the described validation scheme is, in fact, what's being used, you'd expect Verizon's mailer to retain and cache the validation. That way, a single 450 can be turned into a 200 series or a 550.
Also imagine your domain being joe-jobbed. You, as an innocent bystander, then get hammered by Verizon as they try to do a lookup on possibly millions of incoming mails. It's just not a very sane way to reduce their spamload. It's something I'd expect from a smaller ISP, but I would have imagined by now that VZ would have the money to go with something like Brightmail, or develop something in-house like AOL. Charles
As Randy said, 450 means "there's a problem here that should be fixed soon; come back later". If it doesn't change, it's not a 450.
--Steve Bellovin, http://www.research.att.com/~smb