There are two types of Safe Senders lists: the Organization Safe Senders List and your personal Safe Senders List. Both are simply lists of legitimate senders of email.  The email administrator controls the Organization Safe Senders List, which applies to everyone in the organization. You control your personal Safe Senders List to which you can add the addresses of people, organizations, and mailing lists from which you do want to receive mail. 

If a sender's address is included in the Safe Senders List, the Proofpoint Protection Server does not filter the message for spam. (However, it still filters the message for a virus or inappropriate content.) 

There is also an Organization Blocked Senders List and a personal Blocked Senders List. These lists contain addresses of people, organizations, and mailing lists from which you do not want to receive “junk email.”