Assignment by flexible deployment enables mapping of your email settings to smart groups.
An assignment can contain single or multiple smart groups belonging to an Organization Group. Assignments with same email settings are grouped together. You can choose existing smart groups or create new smart groups from the Assigned Smart Groups field as per your requirement.
If you have multiple email settings that are assigned to different assignment groups, then the most recently created settings gets priority. If a device exists in multiple assignment groups that have been configured with different email settings, the device will receive the email settings from the assignment group with the highest priority.