----- Original Message ----- From: "Roy" <garlic@garlic.com> To: "Rich Kulawiec" <rsk@gsp.org>; <nanog@merit.edu> Sent: Friday, December 10, 2004 2:23 PM Subject: RE: verizon.net and other email grief
While I can't speak to what Verizon is using, Both Exim and Postfix have
the
very same feature called "address verification". Its in use at a number of ISPs. My systems reject 1000's of messages every day because of verification failures.
i've never seen this done with postfix, but i know that exim's default 'address verification' for non-local addresses just checks that the domain in the from is valid and that an mx record exists for it. they also have what they call 'callout verification', which is equivalent to what is being discussed, but the documentation makes the drawbacks painfully clear and suggests that it only be used against hosts within the same organization. i'm not a fan of exim, but it appears that although they've given users the rope, they've been diligent enough to label it appropriately. -p --- paul galyinin