IETF SMTP Working Group Proposal at

  Look. The DNS is seriously screwed-up enough as it is. Let's
not take a bad model and replicate it elsewhere.

I'm not saying use DNS specifically, but using something "DNS" like.
Whether it be a database of public keys or certs really doesn't make a
difference at this level.

  Sure. Are you willing to be the first?

If it came down to the wire and something like this were implemented,
and enforced, then yes, I'd be the first in line. If the software, the
system and the means are available, I'd make sure we were registered
before the system went live.

Right. How are you going to enforce *anything* on the Internet? Every single RFC in existence is optional, at best. Every single black list is certainly optional. And until you can control the entire Internet and operate the mail servers for everyone in the world, there's no way in hell that you're going to get everyone to subscribe to the same white list.

  Sorry, guy. Ain't gonna happen.