Turn the Universal Inbox on or off

Sets whether the account's inbox sync (the dashboard's Universal Inbox) is on. This is the same switch as Settings > Universal Inbox in the dashboard. Turning it off stops syncing incoming mail into the inbox; mailboxes and the mail on them are untouched, and it can be turned back on at any time. Idempotent.

email.received webhook events are produced by inbox sync, so turning it off is refused with 409 while any enabled webhook endpoint subscribes to email.received or *. Remove that event from the endpoint (or disable the endpoint) first. Subscribing an endpoint to email.received, or re-enabling one, turns inbox sync back on automatically.