How to use JMAP?
 

If I wanted to write a program that connects to Fastmail by JMAP, where would I start? The JMAP spec itself claims to be transport-agnostic.

I do not think you can yet connect to Fastmail directly using JMAP. Last autumn, it was predicted that the necessary changes to the Fastmail backend to bring it into line with the JMAP spec would take a few months. Mentally, I assumed this meant some time in 2017 (if Fastmail's commitment to this very promising standard remains firm).

The JMAP proxy at https://proxy.jmap.io/ provides a JMAP client that can communicate with an IMAP server (including Fastmail). Examining the source code of the Proxy will probably make it clearer how a JMAP client is supposed to work.

I guess my real question is, in the far-off future when JMAP is a "real" protocol (I assumed it was at least to the point where Fastmail was using it now), how are clients expected to use it? Part of that is my assumption that JMAP is actually meant to be a real protocol, i.e. something you could add to, say, Thunderbird. Is it just an architecture-piece for proprietary* clients?

A transport-agnostic protocol isn't a whole protocol, since at the end of the day the client has to be able to connect to the server

*In the sense that the client is tied to a specific service, and contains knowledge of how that service's particular transport works, even if its source is generally available to be adapted to other services

It's a real protocol. A client desktop client could replace IMAP, SMTP, CalDAV and CardDAV with JMAP.

The transport-agnostic bit means that the actual RPC part of the protocol could be shipped over any transport. The spec documents a binding to HTTPS, which is how we expect most implementations to use it.

There's a few new clients in development and some existing clients in adding support, open-source and proprietary. The Roundcube webmail client should have support soon, and there was a project to add support to Thunderbird, though I'm not sure of its current state.

(I myself have partial support done for fetchmail and offlineimap, both Unix command-line clients).

Do you know of any servers with existing support, or which are expected to have support this year? It will be difficult to generate real momentum without this.

Cyrus will have support this year. It already has fairly complete calendar and contacts support, and mail support is being worked on as we speak. https://cyrusimap.org/imap/developer/jmap.html

I've heard rumours from three different directions that Dovecot are planning support, but I haven't been able to substantiate that.

Then there's the proxy, which is seriously intended to be part of a migration strategy for existing servers that don't yet have support.

In reality, I don't think I'd expect much past exploration from most places until the protocol hits 1.0 - it's probably changing just a little bit too fast for anyone to commit strongly to just yet.

JMAP is on the home straight
 

Hey, that's great news, thanks for sharing this, Fred!
Anyone knows if there's a way to find out if my account is already migrated to the new JMAP system? And are there any ‘real’ differences like better performance, additional features?
Most of all I’d appreciate if FastMail would enable labels instead of folders – of course only as an option for people who want to use it.
Cheers,
Michael

This question was asked on Twitter, and @FastMail responded:

Also:

Thanks again, Fred! :cool: