The Requirements for a Contemporary X.400 Mail System for Distributed Networks

Electronic mail is undoubtedly one of the most successful computer applications in the Information Technology industry. International standards, such as the X.400 Message Handling Systems, have been developed to enable the continual expansion of electronic mail services to a wide range of users. The X.400 standards have comprehensively detailed the functional level of message handling systems but, as with all CCITT standards, has stopped short of defining any requirements for the user interface and a phase approach to the integration of X.400 mail systems for distributed networks.;This thesis presents a functional model, requirements for a contemporary X.400 Mail system for distributed networks, discussion of mail systems, and an integrated phase approach. The functional model was developed from the X.400 recommendations. The functional model, requirements, and the implemented target system was the result of a comprehensive study and experiments.;The X.400 issues focused upon in the functional model, Interim and Target systems include the complexity of specifying message recipient addresses and message options. One of the most promising international standards is the X.500 Directory Services at this writing. X.500 provides a global distributed database of information on people and an extensible range of objects. The directory enables users to store their complex X.400 addresses and provide a more consistent and reliable method to access this information. The functional model, Interim and Target system also describes the requirements for the integration of X.500 Directory Services with X.400 Message Handling Systems. This tightly coupled integration is considered to be a powerful enabling technology for electronic mail users.;The functional model, requirements and Interim and Target system with the integrated phase approach provides the computing science discipline with a proven and functional methodology for X.400 message systems with X.500 directory support. The process in the development was based on sound design principles backed up by extensive experiments with available vendor systems at this writing.;Two architectural phases for the SMTP electronic messaging environment were developed, (1) The Interim messaging architecture supported the X.400 messaging protocol in addition to the existing SMTP protocol messaging systems. (2) The Final Target messaging architecture is achieved with the transition of the SMTP protocol messaging systems to X.400. All non-X.400 messaging systems are upgraded, and replaced by X.400-conformant systems on the desktop and the backbone. Using the analysis of SMTP messaging environment and phase architectural approach, the methodology developed a proposed architecture and phase approach.;In this dissertation, the researcher reviewed available X.400, X.500, and Open Systems Interconnection (OSI) literature. Similarly, the review of HP and DEC applications and primitives strongly suggested that sufficient information was available to develop a detailed X.400 electronic messaging architecture. Several electronic messaging architectures existed in the literature and not all applications were standardized. An X.400 architecture development comprehensively covered a range of messaging functions, and included details at the component level.