[upofadown]

Why not just do things like instant messaging? Everyone signs their email and you only accept email from people you know. Define an introduction message format that would get run through a spam filter and be put in a separate folder. If you want to interact with the entity that sent the introduction then you add them to your keys.

Can be done entirely with stuff available in the fundamentally broken model. I mean, if you want to accept email from just anyone, how can you complain when just anyone sends you email? Not a technical problem, it is a people problem.