My mail server encrypts all of my email with my public PGP key on the way in. So even if you gain access to my email account, you still can't read my email - https://grepular.com/Automatically_Encrypting_all_Incoming_E...

Public key crypto has many usability problems, but it solves a lot of other problems. I wish some of the big mail providers like Google would throw some money and people at it.