Extending an existing mail service to support X.400 message handling

The authors discuss the design and implementation of a prototype X.400 message-handling system for IBM's VM/SP operating system. The system is designed to provide an X.400 extension to the mail service of the professional office system PROFS. For the PROFS user the X.400 extension is transparently integrated into the PROFS user interface. The system allows the use of native X.400 services for interpersonal messaging and therefore is not a gateway between PROFS and X.400 protocols. The system consists of a user agent and a message transfer agent, which implement the X.400 P2 and P1 protocols.<>