Out-of-net host addresses for mail

There is now interest in sustantially extending the scope of the computer mail system used in the ARPANET to allow communication of voice, fax, graphics, as well as text information between users in different networks as wells as within the ARPANET. The discussion of a transition from the current ARPANET sndmsg environment and mechanisms to a more general internet environment and richer mechanisms must consider techniques for continued activity during the transition. In addition, there is a current need for a mechanism to support the interaction of the several already existing NSW-like message environments with the ARPANET message environment. This memo discusses some possible alternatives for computer mail addressing for hosts outside the ARPANET in the short term. This memo is hopelessly Tenex oriented in its descriptions and examples. It helps to keep a few goals in mind while considering the alternative solutions: Goals: 1) Minimum Change to Existing Software. 2) Maximum User Acceptance. 3) Maximum Compatibility with the future Internet Message Environment. 4) Minimum Special Transition Software. These goals are to some degree incompatible, so the evaluation should be expected to involve a trade off. At this point, it would be good to have a model of the current situation and mechanisms of the ARPANET message environment. It is assumed the reader understands it well enough to dispense with a long description of how a message gets from A to B. The important thing is to note the types of players in the picture. There are: message composition (or sending) programs (e.g., Hermes, SNDMSG), in general there are several message composition programs for each type of operating system or host in the network, Postel [page 1]