An Exchange Server 2007 server role that provides anti-spam and antivirus protection and applies messaging security policies to messages in transport between organizations by using a series of agents that act on messages as they are processed by the message transport components. This server role is deployed in the perimeter network outside the Active Directory directory service forest. Computers that have the Edge Transport server role installed handle all Internet-facing mail flow and provide Simple Mail Transfer Protocol (SMTP) relay and smart host services for the Exchange organization.