I guess I don’t understand why you would think that the following wouldn’t work:
- use random email addresses
- encrypt the content with something more secure than PGP (on the client)
- receive the email and decrypt it (on the client)
Sure, it’s plaintext, but I don’t see the downside?
How do I securely communicate what the new email address is? How do I hide IP-level metadata? How do I hide time-level metadata? How do I do PFS?
At some point you're going to keep adding lipstick to the pig until eventually you have something morally equivalent to the pathological example I gave.
Sure, it’s plaintext, but I don’t see the downside?