During the campaign review process, if subscribers in the selected mailing list are restricted by email limits, you will be notified of the count of the same. 

Administrators get notified via the notification bar when a campaign has been requested for exemption, which they can then either exempt or deny.

To handle the request:

    Click the notification for the exemption process of a campaign. This will take you to a page where you have the option to  Exempt or Deny.