If you like, you can specify an exclusive sender (by email address or domain) who will be allowed to forward through the address indefinitely. The exclusive sender can be a full address (e.g., joe@example.com) or just a domain (e.g. example.com)
In the "exclusive sender" blank, can we put in something shorter than a domain: for example "exam", to allow "example.com", "example.ca", "examplemail.com", "exams.com", etc?