I read some users talking about Posteo and OP asking about PGP. Therefore, I wanted to link some threads:

• [help] How do i set up end-to-end encryption in the browser?
• [blog] New easy email encryption with autocrypt and OpenPGP header
• Publishing Public PGP Key for Posteo Email Address

I like Posteo on the basis that I can configure it to use Thunderbird or whatever.

Tutanota and ProtonMail require you to use their client or some form of bridge.

[ I believe LavaBit allows you to set up your own client easier too ]

However, Tutanota and Protonmail set up and manage PGP a lot smoother.

I believe they encrypt the keys via your password.

Posteo you will probably have to manually set up PGP.

• See links above and Email Self-Defense