Intermail and Commercial Mail Relay services
RFC - Informational
(July 1990; No errata)
||RFC Editor Note
RFC 1168 (Informational)
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Network Working Group A. Westine
Request for Comments: 1168 A. DeSchon
INTERMAIL AND COMMERCIAL MAIL RELAY SERVICES
STATUS OF THIS MEMO
This 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. Distribution of this memo is unlimited.
The evolution of large electronic mail systems testifies to the
increasing importance of electronic mail as a means of communication
and coordination throughout the scientific research community.
This paper is a summary of the development of, and a status report
on, an experiment in protocol interoperation between mail systems of
different design. USC/Information Sciences Institute (ISI) began work
on this experiment in 1981 and over the years has provided an
evolving demonstration service for users to exchange mail between the
Internet and a few commercial mail systems.
Recently other organizations have begun to provide similar services,
demonstrating the ongoing need for interoperation of the Internet and
the commercial mail systems. We believe that ISI's pioneering work
in this area has promoted this expansion of service.
These systems include the Internet mail system, the US Sprint
Telemail system, the MCI Mail system, and the Dialcom systems. All of
the systems were designed to operate autonomously, with no convenient
mechanism to allow users of one system to send electronic mail to
users on another system.
The Intermail and Commercial Mail Relay (CMR) services described in
this paper were developed to provide a means for sending mail between
the Internet and these commercial mail systems.
Westine, DeSchon, Postel & Ward [Page 1]
RFC 1168 Intermail and Commercial Mail Relay Services July 1990
The Internet is an interconnected system of networks using the SMTP
mail protocol, which includes the ARPANET, MILNET, NSFNET, and about
700 other networks; mail relays allow the exchange of mail with
BITNET, CSNET, and the UUCP networks as well. To the users, this
Internet looks like one large mail system with at least 100,000
computers and at least 400,000 users. Figure 1 illustrates the path
of a message sent by a user on one Internet host to a user on another
Internet host. For more details on the Internet and connected
networks (see Appendix A).
As commercial mail systems came into popular use, it became clear
that a mail link between the Internet and the commercial mail systems
was necessary (see Appendix B). More and more commercial and
research entities needed to communicate with the Internet research
community, and many of these organizations (for one reason or
another) were inappropriate candidates for Internet sites. The
Intermail and CMR services allow these groups to communicate with
Internet users by purchasing electronic mail services from commercial
Intermail is an experimental mail forwarding system that allows users
to send electronic mail across mail system boundaries. The use of
Intermail is nearly transparent, in that users on each system are
able to use their usual mail programs to prepare, send, and receive
messages. No modifications to any of the mail programs on any of the
systems are required. However, users must put some extra addressing
information at the beginning of the body of their messages.
<<< Figure 1 - Internet to Internet Mail >>>
The earliest version of Intermail was developed in 1981, by Jon
Postel, Danny Cohen, Lee Richardson, and Joel Goldberg . It ran on
the TOPS-20 operating system and was used to forward VLSI chip
specifications for the MOSIS project between the ARPANET and the
Telemail system. The original addressing model used in this system
was called "Source Route Forwarding". It was developed to handle
situations in which a message might travel multiple hops before
reaching its destination.
Later, in 1983, Annette DeSchon converted Intermail into a more
general-purpose mail-forwarding system, supporting forwarding between
the Internet mail system and three commercial mail systems: Telemail,
MCI Mail, and Dialcom [3,4].
Westine, DeSchon, Postel & Ward [Page 2]
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