JMAP for Mail

JMAP for Mail (RFC8621) is an extension to the JMAP Core protocol that allows users to manage their email accounts using the JMAP API. The extension covers uploading, deleting, and listing emails, as well as managing mailboxes and related settings. Message-level limits and mailbox-shape constraints are carried on the Email singleton (found in the WebUI under Settings › Email › Defaults, Settings › Email › Encryption, Settings › Email › Limits, Settings › Email › Storage); JMAP request-parsing limits are carried on the Jmap singleton (found in the WebUI under Settings › Network › JMAP › Limits, Settings › Network › JMAP › Push, Settings › Network › JMAP › WebSocket).

Mailbox settings

Mailbox shape is controlled through two fields on the Email singleton:

• maxMailboxDepth: maximum depth of nested mailboxes a user can create. Default 10.
• maxMailboxNameLength: maximum length of a mailbox name. Default 255.

Example:

{
  "maxMailboxDepth": 10,
  "maxMailboxNameLength": 255
}

Email settings

Message-size limits are set on the Email singleton:

• maxAttachmentSize: maximum size, in bytes, for an email attachment. Default 50000000.
• maxMessageSize: maximum size, in bytes, for an email message. Default 75000000.

The upper bound on the number of email messages that can be parsed in a single JMAP request is set on the Jmap singleton through parseLimitEmail, which defaults to 10.

Example:

{
  "maxAttachmentSize": 50000000,
  "maxMessageSize": 75000000
}

And on the Jmap singleton:

{
  "parseLimitEmail": 10
}