I haven't done it, but some years ago a Mike... C.? published a description of how he did email, then. Public/private keypairs. Inbound email would arrive at

I haven't done it, but some years ago a Mike... C.? published a description of how he did email, then. Public/private keypairs. Inbound email would arrive at his server and immediately be encrypted using a public key. It would sit on his server encrypted. When he pulled it off, he would decrypt it at his client using the private key. If the server was compromised, at that point in time, all the adversary would get would be a bunch of encrypted messages to which the relevant key for decryption was not present on the server. Just to be clear, this was his keypair, used to keep incoming email at rest on his server encrypted with no local means to decrypt. Irrespective of whether the sender did or didn't use encryption when sending the email to him. I presume one would want some sort of canary to warn of compromise with respect to further messaging that might arrive or be sent. Outbound, I presume he was not retaining copies on the server and was using whatever degree of encryption the recipient could handle and the situation warranted. P.S. I realize this doesn't solve your "you're SPAM" labeling by an ever more differentiating Internet email network. P.P.S. I'm pretty sure this is it. Site/page design may have been redone a bit. Just if and as this interests anybody -- I haven't taken the time to reread it, right now. https://www.grepular.com/Automatically_Encrypting_all_Incoming_Email https://www.grepular.com/Automatically_Encrypting_all_Incomi...