I'm talking about PGP encrypting a message body and attaching the public key. Old school style. Every provider supports this, it's just plain cyphertext.
Discussion
Thanks for pointing out. So everyone has pgp keys already so you can use their public key to encrypt an email for them?
Unfortunately no. That's what providers like Proton are good for (doing this for you). But ideally all people would be able to use GPG/PGP. Of course that's a lot to ask (hence e2e encrypted providers like the aforementioned)