X.400 and X.500: An Introduction is aimed at those involved in current or planned in the management of X.400, including the message manager, planner or network systems, and software developers. Because the standards are very abstract, John Rhoton has described them with a picture of MAILbus 400 and Digital X.500, which is a comprehensive and faithful implementation of standards. Overview MAILbus 400 as X.400 standard explanation Provides introductory material to move them from the Message Router to MAILbus 400