I think we need to completely reimagine email, though a proper fix is likely pretty easy. I think social networks have done a pretty good job at the basic idea:

- ask to connect, perhaps with a short message as to why (maybe limit to 100 text characters) - once approved, communication is encrypted (PGP keys are exchanged behind the scenes)

I think that would drastically limit the amount of spam, phishing, and intercepted messages, which is good for everyone. Unfortunately, I think it's also quite unlikely to hit the mainstream.