By "replace SMTP" I mean the whole email protocol stack, not only SMTP. I'm not proposing to replace it for all situations overnight; of course SMTP etc will be

By "replace SMTP" I mean the whole email protocol stack, not only SMTP. I'm not proposing to replace it for all situations overnight; of course SMTP etc will be used for decades. TMTP also covers most IMAP/POP use cases. And it allows short, plain-text messages (see Ping) to make first contact with others -- necessary when that server has less restrictive membership requirements. Authenticity is a double-edged sword. For certain confidential content, you want the recipient to know that it originated with the sender, but you don't want anyone else to know that in the event the content is leaked or stolen. I believe the extinction of email for person-to-person & app-to-person correspondence is a foregone conclusion, due principally to phishing. The question is what should we do now, and the answer is clearly not chatrooms (which are of course useful in certain circumstances).