Hand delivered mail

Not really. Email is inherently broken due to capture by just a few big corps and "anti-spam" requirements. You could try to use GPG but that requires the other party to be on board and for you to have shared keys and for both of you to use secure inboxes, i.e. self-hosted.

At that point you might as well use a messaging service that's meant for secure communication from the ground up.

If you want private communication, you have to encrypt your emails with PGP/GPG. You could also connect to the email with a VPN, this is an additional layer of security, not an alternative to GPG encryption. There is no email provider that you can trust.

private/self-hosted smtp servers i imagine. it just doesn't strike me that these email services that offer free inboxes would be any good for privacy concerns (proton mail, tutanota, whatever). but they're good to sign up for shit i suppose.