You may need to disable or enable or create the events-rules-actions regarding catalog notification email . you will need to know where those rules are defined .
where to find the email template for catalog request's cancel notification email ?
service catalog 12.9 , 14.1 , 17.1
1. login service catalog GUI as a user with service delivery administrator role
2. go to Administration -> Events-Rules-Actions , the catalog request's notification email rules-actions are defined under "Request Pending Action Change" Event type. Catalog's email notification is triggered based on the rules-actions defined there