PROTOCOLS FOR MESSAGE HANDLING.

The CCITT has recently defined a new global telecommunications service known as Message Handling, which combines electronic mail with established telematic services such as telex and facsimile. The global feasibility of this new service owes much to the protocols that have been defined for message transfer and manipulation. This paper describes these protocols, and analyzes their structure and foundation as application layer protocols in the Reference Model for Open Systems Interconnection. The paper identifies their dependence on the services of the session layer, and the potential problems in accommodating a presentation layer. The reasons for the overall simplicity of the protocols are elucidated, and applications outside Message Handling are identified.