A Notify activity is an activity with Activity Type of Notify
(on the Security tab). Such an activity when referenced in a flow, typically sends out correspondence, such as an email message, when a flow execution creates an assignment. Typically, the application sends this correspondence to one or more of the work parties identified in the work item, and reports progress to that party.
For example, the standard activity named Work-.NotifyAssignee sends an email message to a user who will receive the new assignment. The activity runs when the system creates the assignment, not later when the assignment is performed.
When editing a flow rule :
To mark an activity in a class derived from the Work- base class for use as a notify activity, set the Activity Type field (on the Activity form Security tab) to Notify
.