The JMAP protocol defined in draft-ietf-jmap-core is designed to be extensible to multiple datatypes which are useful for personal information management related to email stores. Now that draft-ietf-jmap-mail is completed, the working group will produce specifications for related data types, begining with calendars. The calendar work will be based on draft-ietf-calext-jscalandar as the data format. This working group will consult with the CALEXT working group to ensure that calendar access via JMAP remains compatible with existing calendar standards. Extensions to the existing core and mail JMAP specifications are also within scope for this working group, for example any additional parts of SIEVE, IMAP, SMTP submission, as well as transport of JMAP over different protocols than HTTPS. Work on JMAP extensions will be bound by the following constraints: 1) The work of this group is limited to developing protocols for a client synchronising data with a server. Any server-to-server issues are out of scope for this working group. 2) Object models will use existing IETF work where possible. 3) JMAP Extensions will be built following the core principles: 3.1) The server will not be required to perform work not explicitly requested by the client, and the default should always be the mode which requires the least server work. 3.2) The client can discover limits enforced by the server on resources or request complexity. 3.3) Where side effects generated by the server are optional, the protocol will default to no side effects, and the client must explicitly request that those side effects happen (for example: sending a calendar invitation or reply when updating an event) The working group will deliver documents for the following: - JMAP access to calendars using the JSCalendar format - accessing JMAP over Websockets - handling of S/MIME email messages (e.g. signature verification) over JMAP - Message Disposition Notifications (RFC 8098) via JMAP - other extensions which the working group considers related to email and compatible with the constraints listed above