Doesn't exist yet. Hopefully, once the standard is finalized and has a server to offer public JMAP support will be adopted by email clients. I'm currently wor

Doesn't exist yet. Hopefully, once the standard is finalized and has a server to offer public JMAP support will be adopted by email clients. I'm currently working on adding support for JMAP, but to have reference server I need to build and setup latest Cyrus from scratch which was a challenging experience.