A messaging standard that can be used by many messaging systems.
A Microsoft Exchange Server component that is integrated with the message transfer agent (MTA) and can be configured to connect routing groups within Exchange or to route messages to foreign X.400 systems.
A set of standards developed by the International Standards Organization (ISO) that define distributed directory services.
A standard certificate format developed by the International Telecommunication Union - Telecommunication (ITU-T). X.509 version 3 is the industry-standard format used by Microsoft Windows Server 2003 certificate-based security processes.