In message <BECC768F.C3FD%dgolding@burtongroup.com>, Daniel Golding writes:
Reputation is a missing element in all sender authentications schemes and will (likely) be solved separately.
No approach is perfect, but building closer to a solution is preferred over sitting on our hands and debating, which (historically) seems to be the IETF's approach.
I'm not a fan of authentication as an anti-spam technique (see my Inside RISKS column for details). That said, if you're going to use the concept there are good and bad ways to do it. SPF (and hence Microsoft's scheme) are really lousy ways to do it, for the reasons John gave. Beyond that, a lot of people at the IETF had the impression, rightly or wrongly, that Microsoft was trying to use its patents as another weapon to use against open source software. The IETF isn't nearly as nimble as it should be, but rushing to adopt a bad solution is not a good idea. --Steven M. Bellovin, http://www.cs.columbia.edu/~smb