The only question left is if there are any *technical* components to
doing so
(which would be the IETF's preserve), and, if so, what they are.
It surprises me that so many people are so eager to declare defeat
before even trying the protocol route. (With current protocols defeat
is pretty much inevitable.)
There is an obvious issue with the protocol route: from a protocol point
of view, it is quite hard to distinguish unsolicited commercial e-mail,
which we would label spam, and unsolicited acceptable e-mail, which
could be more than welcome.