I was interested in hosting my own mail server that provides a similar level of privacy for users as Protonmail, ie the server admin cannot read any emails, even those which are not E2EE with PGP. Is there a self-hostable solution to this?
I’m aware the server admin can’t read emails that were sent encrypted using the user’s PGP key, but most emails I get are automated emails from companies/services/etc without the option to upload a public key to send the user encrypted email. If you’re with a service like Protonmail, the server admin still cannot read even these emails.
That can easily be achieved with dovecot and a sieve script.
but then the admin can still read the mail while it arrives ;-)
That’s true of protonmail too
There’s no such thing E2EE email. The protocol doesn’t support it.
That’s not really true, S/MIME is a thing
And gpg, which op mentions. But the devil’s in the details with encryption.