JMAP for mail, contacts, calendar and files landed in Stalwart mail server about 5-6 months ago. In a discussion here on HN( https://news.ycombinator.com/item?id=45672336 ), a member( @solarkraft ) floated the idea of using Stawart as the "server" implementation of JMAP and using something like mbsync to sync IMAP from their mail provider. And build a client on top of this Stalwart "server." This might very well be the client to serve as a way to use the new JMAP protocols and not self-host.