[bjourne]

IMAP is mostly slow as hell when dealing with large mailboxes. For example fetching the 10 most recently updated threads (for a sane definition of what a thread/conversation is, which imap doesn't deal with at all) is insanely slow. It entails scanning the whole mailbox trying to figure out what the threads are and when someone last posted to them. Not fast when you can have millions of mails in a mailbox. Is that the kind of problems JMAP might solve?

Also interested in hearing if you know anything about GMail's json api? Surely they must have something similar to JMAP which their web client is using even if it the api is proprietary?