> Spam is never eliminated - just reduced. Most spam comes from virus > infected zombies that talk SMTP. If end users were by default set up so > that they can only send email by IMAP then you can block off SMTP ports > for end users isolating them from the SMTP world. That would take a huge > bite out of the spam problem.
Which is something that many ISPs and corporations already do. What makes you think that any more of them will do it if your plan were to be implemented? Responsible networks are already blocking port 25, while irresponsible networks (generalizing to make a point) aren't. What's going to happen to make the irresponsible networks change their ways? Why hasn't it happened already? What kind of incentive does your plan specifically provide to help change those network owners' minds?
