http://www.rfc-editor.org/rfc/rfc1168.txt
RFC 1168: Intermail and Commercial Mail Relay services, A. Westine, A.L. DeSchon, J. Postel, C.E. Ward1990-07-01T23:00:00-00:00This RFC discusses the history and evolution of the Intermail and Commercial mail systems. The problems encountered in operating a store-and-forward mail relay between commercial systems such as Telemail, MCI Mail and Dialcom are also discussed. This RFC provides information for the Internet community, and does not specify any standard.