Notifying user of task assigned in Action Center

When a Form task or External task is assigned to a user in Action Center, how does the user gets notified of it? I cannot see any email getting sent to user’s registered email address informing of the assigned task.
Ideally user should receive and email with a link in it which will take him/her to the task page directly.

Is there any setting for this in Orchestrator which I am missing?