FastMail, Aliases, PGP, Custom Domains, Privacy

Protonmail - they keep your private keys, they don’t allow to use imap, pop3. Yes, I know they have Proton Bridge. LOL Tuta - it’s not even worth to write about it. Mailbox.org - you can upload only public keys which are used to encrypt your e-mails on the server. You can use IMAP, POP3 with the client of your choice. They have their own Tor exit node, they allow you to connect via .onion address too.