John,
IMHO, I think that we should focus on RFC2821 HELO and in-addr.arpa
first since they seem to break the least amount of things.
JL> That's a funny reason -- sounds a lot like the drunk searching for
JL> his keys next to the street-light because "the light's so much better
JL> here!".
actually, it sounds like someone who is looking to do something quick
and productive, with reduced risk.
breaking a system that is used by perhaps 1 billion people adds
considerably to the risk of the changes.
for a group seeking to make a number of changes, finding the smallest
useful change is often a good way to learn how to tackle more
difficult tasks.
If the entire purpose of MAIL FROM checking is to introduce a
hook for reputation, than HELO with domain names will satisfy that.
JL> That is simply _not_ "the entire purpose". I don't even believe
JL> it is a major purpose. The purpose of RFC2821 MAIL-From checking is
JL> to get a useful bounce address, so that we don't have to catch all
JL> the problems during the SMTP session.
the proposed mailfrom checking schemes do nothing to prevent a spammer
from creating useless addresses and placing them in mailfrom.
so the scheme merely blocks one particular kind of spammer abuse,
which spammers will be able to nicely route around.
JL> Besides, we're not going to "break" store-and-forward. Really!
author-based mta registrations schemes do break store-and-forward
across the open Internet.
Absent other substantive changes, such as widespread addition of
dynamic DNS capabilities, they make SMTP work only as a direct channel
between the originator's site and the recipient's site.
d/
--
Dave Crocker <mailto:dcrocker(_at_)brandenburg(_dot_)com>
Brandenburg InternetWorking <http://www.brandenburg.com>
Sunnyvale, CA USA <tel:+1.408.246.8253>, <fax:+1.866.358.5301>