'the original message had malicous or deceitful intent' could be mistaken
for
about the CONTENT of the message. I don't think anyone wants to touch
THAT.
There are many products that do exactly this today. I know because I've
helped to build one that my employer is selling. For example, you can
configure the server to drop the message (and not notify the sender) if the
message is virus infected.
My point is, if you're going to change the SMTP protocol standard to admit
that servers may be performing some kind of post-acceptance analysis of the
message, you shouldn't assume that the analysis is limited to information
available on the SMTP envelope.
Daryl Odnert
Tumbleweed Communications
daryl(_dot_)odnert(_at_)tumbleweed(_dot_)com