Thanks for making a really interesting point that I didn't have space for in the Confidentiality post, but did touch on in the Integrity post. The whole thing

Thanks for making a really interesting point that I didn't have space for in the Confidentiality post, but did touch on in the Integrity post. The whole thing with email is that it's your own immutable copy. If you can't even read it without going to some website that may or may not exist at a later date, then you don't really have a copy. So you wind up having to extract the plaintext and then keep a copy of that somehow to ensure you never lose access. Sounds like normal email, the hard way.