rfc1168.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.

Network Working Group                                         A. Westine
Request for Comments: 1168                                    A. DeSchon
                                                               J. Postel
                                                               C.E. Ward
                                                                 USC/ISI
                                                               July 1990

              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.

INTRODUCTION

   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
   companies.

INTERMAIL

   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 [1]. 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]

RFC 1168      Intermail and Commercial Mail Relay Services     July 1990


   As it became apparent that the level of generality of Source Route
   Forwarding was not needed, and as Intermail gained acceptance among
   users, an easier approach to addressing was developed.  The new
   addressing model is called "Simple Forwarding".  This form of
   addressing, like Source Route Forwarding, appears at the beginning of
   the text of each message.  It can be used to include various Internet
   mail header fields in addition to the standard "To" and "Cc" address
   fields.  This format also allows the use of special address formats,
   such as U.S. postal addresses and TELEX addresses, which are
   supported by the MCI Mail system.  The Intermail system performed
   partially automated error handling.  Error messages were created by
   the Intermail program and were then either approved or corrected by a
   human postmaster.

   Figure 2 illustrates the pathways between the user mailboxes in the
   commercial mail systems and the user mailboxes in the Internet via
   the Intermail accounts and program modules.  Figure 3 shows the
   Intermail processing in more detail.

              <<< Figure 2 - Commercial Mail to Intermail >>>

                  <<< Figure 3 - Intermail Processing >>>

COMMERCIAL MAIL RELAY

   In 1988, the Commercial Mail Relay (CMR) was developed to run on a
   dedicated UNIX system, replacing the TOPS-20-based Intermail system.
   The CMR is a store-and-forward mail link between the Internet and two
   commercial systems, Telemail and Dialcom. The only remaining
   forwarding performed by the TOPS-20 Intermail system is in support of
   the MCI Mail system.  (This is planned for conversion to the CMR.)
   The CMR supports relay-style addressing in the "Internet to
   commercial system" direction, as well as Simple Forwarding in both
   directions.  One advantage of relay-style addressing is that users
   from different commercial systems can appear on Internet mailing
   lists.  Another advantage is that the reply features of most Internet
   user applications can be used by Internet users to respond to mail
   that originated on a commercial system. Unfortunately, since we do
   not have access to the address-parsing software on the commercial
   systems, it is not possible for users of the commercial systems to
   enter addresses directly into the message header, and they must
   continue to use Simple Forwarding.

   The CMR supports automated error handling, which enables the system
   to provide faster turnaround on messages containing addressing
   errors, and requires much less intervention from a human postmaster.





Westine, DeSchon, Postel & Ward                                 [Page 3]

RFC 1168      Intermail and Commercial Mail Relay Services     July 1990


DESCRIPTION OF THE CMR SYSTEM

   The Multi-channel Memo Distribution Facility (MMDF) is used as the
   system mail software because of its notion of separating the mail
   queue into separate channels [5].  This makes it easy to dedicate a
   channel/queue combination to each commercial system.  Internet mail
   comes in over the standard SMTP port, and the system parses the
   destination address, queuing the message in the proper outgoing
   queue.  A tag can be added to outgoing traffic so that replies can be
   made without any special processing at the destination site.

   The CMR uses a relay mailbox on each commercial system.  Commercial
   users send mail to this mailbox with a Simple Forwarding Header (SFH)
   at the head of their message text.  Each channel, in addition to
   sending outgoing mail into the commercial system, reads all messages
   in the relay mailbox and places them in a spool file in the CMR host
   computer.

   The processing of the spool file is performed by a single daemon. It
   parses each commercial system message header to find the sender and
   subject, then it searches for and processes the SFH.  The SFH
   contains the destination Internet addresses.  Figure 4a illustrates
   the path of mail from the Internet to the commercial sytems. Figure
   4b illustrates the path from the commercial systrems to the Internet.
   Note:  MCI Mail is not yet implemented.

   The CMR employs a simple accounting mechanism:  a shell script counts
   the number of times a string marker occurs in the MMDF logs.  At the
   end of the month, another script uses an "awk" program to total the
   number of messages sent and received with each commercial system. The
   Commercial Mail Relay is being developed by Craig E. Ward.  Ann
   Westine served as the Postmaster for both Intermail and the CMR until
   March 1989.  Currently, our Action Office serves as Postmaster.
   Questions may be sent to "[e-mail]".

          <<< Figure 4a - The Internet to Commercial Systems >>>

          <<< Figure 4b - Commercial Systems to the Internet >>>

COMMERCIAL SYSTEMS SERVED

   The CMR provides mail relay service between the Internet and two
   commercial electronic mail systems:  the US Sprint Telemail system
   and the Dialcom system.  A CMR connection to MCI Mail is under
   development.  MCI Mail is currently served by the TOPS-20 Intermail
   system.  See Appendix C for recent traffic data.





Westine, DeSchon, Postel & Ward                                 [Page 4]

RFC 1168      Intermail and Commercial Mail Relay Services     July 1990


   Telemail is an international commercial service.  Some of the
   Telemail systems served by the CMR include MAIL/USA, NASAMAIL/USA,
   and GSFC/USA.  Some government agencies, such as NASA and the
   Environmental Protection Agency, have dedicated Telemail systems.
   Companies also exist that purchase bulk services from Telemail and
   resell the service to individuals.  Omnet's Sciencenet is a very
   popular example of this type of service.

   Dialcom is a commercial service similar to Telemail in that it has
   facilities for allowing groups to purchase tailored services, and
   some government agencies (such as the National Science Foundation and
   the U.S.  Department of Agriculture) have special group-access plans.
   The IEEE Computer Society also has a dedicated group service, called
   IEEE Compmail, which is open to members of the IEEE Computer Society.

   MCI Mail is operated by MCI and is marketed to large companies as
   well as individual users.

   Specific examples of the users of Intermail and the CMR are as
   follows:

   1) Scientists in Oceanography, Astronomy, Geology, and Agriculture
   use Intermail and the CMR to communicate with colleagues.  Many of
   these scientists have accounts on "Sciencenet", which is actually
   part of a Telemail system administered by Omnet.

   (2) The IEEE Computer Society's publication editors use the Dialcom
   system "Compmail" to manage the papers being prepared for their
   numerous publications.  Many of the authors are in university
   departments with access to the Internet. Intermail and the CMR
   support a significant exchange of large messages containing
   manuscripts.

   (3)  NASA uses Telemail systems for its own work and has extensive
   exchanges through its own relay service, as well as Intermail and the
   CMR, for communicating with university scientists on the Internet.

   Other developments to interoperate between the Internet and
   Commercial mail systems are:

      (1)  The Merit gateway to Sprintmail and IEEE Compmail

      (2)  The CNRI gateway to MCI Mail

      (3)  The Ohio State University gateway to Compuserve, and,

      (4)  NASA-Ames gateway to Telemail




Westine, DeSchon, Postel & Ward                                 [Page 5]

RFC 1168      Intermail and Commercial Mail Relay Services     July 1990


ACCEPTABLE USE POLICY FOR INTERMAIL AND THE CMR

   The Internet is composed of many networks sponsored by many
   organizations.  However, all the Internet's long-haul networks are
   provided by U.S.  government agencies.  Each of these agencies limits
   the use of the facilities it provides in some way.  In general, the
   statement by an agency about how its facilities may be used is called
   an "Acceptable Use Policy".

   The various agencies involved in the Internet are currently preparing
   their Acceptable Use Policy statements.  Most of these are in draft
   form and have not been released as official agency statements as yet.
   None of these policies are currently available as online documents.

   In the least restrictive case, all bona fide researchers and
   scholars, public and private, from the United States and foreign
   countries (unless denied access by national policy) are allowed
   access.

   The Intermail and Commercial Mail Relay (CMR) systems at ISI are
   resources provided by the Defense Advanced Research Projects Agency
   (DARPA) for computing and communication.  Use of these resources must
   be limited to DARPA-sponsored work or other approved government
   business (or must otherwise meet the acceptable use policy of DARPA),
   only.

   However, DARPA, as a member of the Federal Research Internet
   Coordinating Committee (FRICC), has agreed to the FRICC draft policy
   for communication networks, which provides in part that:  "The member
   agencies of the FRICC agree to carry all traffic that meets the
   Acceptable Use Policy of the originating member agency".

   Thus, e-mail messages (i.e., "traffic") that meet the Acceptable Use
   Policy of an agency and pass through some facility of that agency
   (i.e., "the originating member") on the way to Intermail or CMR are
   allowed.

   The current member agencies of the FRICC are DARPA, NSF, DOE, NASA,
   and NIH.

   BITNET and UUCP (and other) networks are interconnected to the
   Internet via mail relays.  It is the responsibility of the managers
   of these mail relays to ensure that the e-mail messages ("traffic")
   that enter the Internet via their mail relays meet the Acceptable Use
   Policy of the member agency providing the Internet access.