OpenPGP mail with resend capacity (like a Nym server)
I think it is more simple to express the idea with an example. But it is kind of an old school nym server capacity.
Alice want to send a secure message to Bob. She can't connect directly to Protonmail for technical reason. Let say she is stuck with a really poor data connection. But she can receive email using an mail client (like alpine)...
How can she contact Bob if he can't use GPG because it is too complex for him.
Alice send an encrypted message to firstname.lastname@example.org encrypted with protonmail public key and digitally sign with alice registered openPGP key. The body of the message when received by protonmail is decrypted and the signature verified. If all is right, the server read the following line in the body of the message:
The server reroute the email to Bob. When Bob write back to Alice, a rule she programmed tell the server to encrypt bob email in openPGP and send the encrypted copy to alice other email.