Contacts as safe senders.

Our system allows administrators to define a list of safe senders for the entire domain. We added the option to enable each user's contact list as safe senders as well.
If the domain administrator enables the option, each email address present in the users contact lists is automatically considered a safe sender for the domain.
Note that a contact address just needs to be present in the contact list of one user to be considered safe for every other users of the domain.