I am very interested in JMAP, a standard proposed by FastMail as a replacement for the aging IMAP protocol.

I have a few observations:

  • As of now, FastMail uses the mail folder metaphor. A message exists in exactly one mail folder. JMAP supports the concept of messages existing in multiple mail folders, but does not require that a server support that. I am very curious as to whether this is a sign that FastMail intends to support the concept of labels or tags in its service.
  • In addition to being an open standard, this API appears cleaner and easier to use than the Gmail API. I would love to see Google move towards JMAP.
  • JMAP does not allow the client to view or set server-side filters. I can appreciate why this might be excluded from version 1.0, but I hope this is revisited in the future.