Propagating messaging preferences of one or more users from a recipient mailbox to a perimeter network administering e-mail content blocking and routing. A content filtering application located outside a trusted network receives messaging preferences information from within the trusted network regarding the mail recipients. This messaging preferences information may be utilized to allow certain pre-authorized messages from particular senders to bypass content filtering. Moreover, the messaging preferences information may be hashed to further protect the information on the perimeter network and to speed in review and comparison of the messaging preferences information. In addition, other types of user-specific information may be propagated to the perimeter network for use with other applications other than messaging.