Protonmail, a secure mail system, is now up and running for public use. I’ve just opened an account and it looks just like any other webmail to the user. Assuming everything is correctly implemented as they describe, it will ensure your email contents are encrypted end-to-end. It will also make traffic analysis of metadata much more difficult. In particular, at least when they have enough users, it will be difficult for someone monitoring the external traffic to infer who is talking to whom and build social graphs from that. Not impossible, mind you, but much more difficult.
If you want to really hide who you’re talking to, use the Tor Browser to sign up and don’t enter a real “recovery email” address (it’s optional), and then never connect to Protonmail except through Tor. Not even once. Also, never tell anyone what your Protonmail address is over any communication medium that can be linked to you, never even once. Which, of course, makes it really hard to tell others how to find you. So even though Protonmail solves the key distribution problem, you now have an address distribution problem in its place.
But even if you don’t go the whole way and meticulously hide your identity through Tor, it’s still a very large step forwards in privacy.
And last, but certainly not least, it’s not a US or UK based business. It’s Swiss.