Are there any plans to support JMAP?
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Best regards
Mike
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I am interested in updates on JMAP as well
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Interested in this as well because I can run my own JMAP proxy and make email synchronisation faster and probably reduce battery drain on mobiles
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JMAP is not really meant to be used with desktop client apps, rather it is designed to work with webclients instead.
However, we did investigate the possibility of supporting it, and even created a prototype eM Client application. Unfortunately the only real implementation of JMAP is Cyrus, which is full of bugs and incomplete features, so not really usable.
At this time we don’t see any benefit using JMAP instead of IMAP, but if it goes through a rewrite and has some actual server support, we may revisit it in the future.
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Add me +1
BTW, Stalwart http://stalw.art has JMAP server to text against
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This would be awesome!
stalw.art server seems pretty decent https://github.com/stalwartlabs/mail-server
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Likewise +1 for this, I been testing out stalw.art also and JMAP is now available on it!
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Hello everyone,
I wanted to share that my MSP company implements and provides support for mail servers. Over the past years, we’ve seen significant growth with the Stalwart mail server, and our clients have given us overwhelmingly positive feedback. It truly has a bright future ahead.
So, it would be fantastic to see support for the JMAP protocol in the eM Client application. This would enhance the user experience and further integrate with modern mail server solutions.
Looking forward to your thoughts!
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Would love to see JMAP in eM Client!
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JMAP support would be nice. 
Maybe the new Thundermail will support it too.
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Fastmail (https://www.fastmail.com) also supports JMAP
I personally don’t see it as a big advantage over IMAP and still also could be buggy as @Gary advised further up this thread in 2024.
There is a suggestion to add JMAP support via the following Sleekplan page you can vote on.
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If I got it right, JMAP would cover synchronization of calender and ToDo-Lists. Would be very helpfull, due to our provider can not offer CalDav.
Thomas
Quick update for this thread, since the situation has changed materially:
Server implementations are no longer the problem. Stalwart Mail Server (Rust, open source) is production-ready and fully JMAP-compliant. Fastmail has had JMAP for years. The Cyrus-bugginess argument from 2024 is outdated.
Thunderbird is now actively implementing JMAP. Thunderbird for iOS is being built JMAP-first (development in progress throughout 2025). The desktop and Android versions have JMAP explicitly on the 2026 roadmap. Thundermail, their new email hosting service, will ship with JMAP support.
This matters for eM Client competitively: once Thunderbird ships JMAP on desktop, eM Client will be the only major cross-platform client without it — while Thunderbird gains a genuine technical advantage for large-mailbox users and privacy-focused organizations.
I’d encourage the team to revisit the prototype using Stalwart instead of Cyrus. The experience will be very different.
If you currently Google about the latest in JMAP implementation it shows issues eg: Quote:-
“Recent reports (as of early 2026) indicate that while major players like Fastmail use it in production, active development and testing (e.g., in Stalwart) still reveal bugs in JMAP implementations”.
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Bumping this, the people want JMAP!!!
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Which reputable email service providers beside Fastmail (who developed the spec) have mature support for JMAP? Thunderbird’s implementation is far from being mature, in the same way Thunderbirds EWS implementation is.
So, unless more reputable email providers support JMAP, I don’t see lots of people really wanting it. At least Google, Microsoft, and just about every other email provider out there support IMAP, regardless of whatever API scheme they put on top of the HTTP(s) protocol for additional access methods. I do like how JMAP includes Calendar and Contact support, but even CalDAV and CardDAV is more widely supported (GMail for example), especially in iOS/MacOS mail, contact, and calendar apps.
The problem is not eM Client not supporting JMAP, it is that most email service providers not finding it worth the effort to support JMAP. When that changes then it will make more sense for eM Client to support JMAP. Wake me up when Google and Office365 support JMAP in the same way they support IMAP or their native APIs.
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Google & Office365 have monster infrastructure’s so it’s costly for them to do this. Not everyone rely’s on those providers. For those who self-host and can benefit from speed and other aspects of JMAP which is growing day-by-day as people are tired of these giant’s wanting to control everything and push everyone to their monthly cloud-services you want to alienate that community just because Google & MS don’t support it? That’s absurd.
I just don’t think enough people self-host email with a mail server that supports JMAP to make the labor cost justified for eM Client to add JMAP. I used Google & MS as an important example since they are large email providers which eM Client directly supports, but it goes back to my question, which reputable email service providers beside Fastmail (who developed the spec) have mature support for JMAP?
My point was not enough reputable email service providers provide JMAP support to justify any effort to add it into eM Client. If more providers start offering it at some point, then it might be more justified, but I don’t see that currently. If I am wrong and lots of people use a email service that supports JMAP, then they should vote to have that feature, and the vote numbers will speak for the need.
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@lancealot I understand where you’re coming from.
One of the best features of of eM Client is that it fully supports Google/Gmail Labels as Tags and displays on each message all of the Labels/Tags that apply to that message.
The real issue, in my view, is that Fastmail is the only alternative to Google/Gmail that offers true label support (with the ability to tag e-mails with one or more labels and the labels all showing up in IMAP e-mail clients), but eM Client does not currently support Fastmail labels/tags. Both eM Client and Fastmail would be a much greater value if eM Client fully supported Fastmail labels. Whether that is through JMAP or some other method doesn’t matter. … It would make eM Client and Fastmail the go-to (and only!) desktop e-mail client and e-mail service for anyone who wants to use a desktop e-mail program with true label/tag support without being stuck with Google/Gmail.
Feature Request: enable labels in Fastmail - #13 by SilverM99 @Gary