[protonmail]

Regarding Proton Mail's encryption: Proton's servers don't hold your private key directly — it is generated client-side and stored encrypted with your password. You can also import your own keys: https://proton.me/support/pgp-key-management. That way, you can stay in full control of your keys.

Additionally, Proton Mail uses OpenPGP internally, so Proton-to-Proton messages are always protected by PGP. Even for external messages, contacts don't necessarily have to set up PGP encryption manually; the email client can do so, enabling the use of end-to-end encryption between different providers with minimal hassle.