This text is aimed at advanced e-mail users, CIO's managers, MIS professionals and system administrators. It explains what users should expect from an e-mail system, how to expand or fully use a system, options for connecting to other systems, and specifics on how to connect to other systems. This guide is suitable for those planning a new system, planninng to switch to another system, or trying to merge or access different systems, and use on-line services.