JMAP: It’s Like IMAP but Not Really

As a subscriber to the IMAP protocol mailing list for the last 15+ years (also an actual thing), I recognize Bron from many informative replies to befuddled posters about the IMAP protocol, or the Open Source Cyrus IMAP server he contributes to. Short of the ground breaking (not really) Cypht webmail program, I would say JMAP is the best thing to happen to E-mail in a LONG time. Right now development versions of the Cyrus IMAP server support JMAP, and FastMail is using it in production for some of their users.

Source: unencumberedbyfacts.com