I imagine that this protocol would be eligible for creating an e-mail replacement.

E-mail is quite asking for new features which you get for free under this protocol:

• Native (without GPG) authentication of the sender, and encryption of the message
• Authentication of the whole conversation. If you are replying to an e-mail, there would be a link to the previous message, and there would be no reason not to have one.
• No problem accessing messages on untrusted networks
• No passwords, just a private key you can keep around

As I understand it, this protocol allows an e-mail to refer to previous messages on a conversation without copying the text, which has the hassle of the previous message being stored onto the current one (possibly modified!).

"addresses" could be SHA hashes of pubkeys, so if you are paranoid you can exchange public keys and be sure you are always talking to that person.

Would this protocol be feasible to create a new way to send electronic messages?