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rfc:rfc1168

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 "Intermail-Request@ISI.EDU".
        <<< 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.

Westine, DeSchon, Postel & Ward [Page 6] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 In addition, we cannot allow CMR or Intermail to be used simply as a
 bridge between two commercial systems, even though CMR has this
 technical capability.  At least one end of the communication must be
 related to FRICC acceptable use.

DETAILS OF CMR SYSTEM USE

 The CMR host computer is Internet host INTERMAIL.ISI.EDU
 (128.9.2.203).  The users of the commercials system are required to
 know the proper gateways between the Internet and other networks such
 as BITNET, CSNET, or UUCP.  Users on networks interconnected to the
 Internet likewise need to know how to reach the Internet to send mail
 through INTERMAIL.ISI.EDU to a commercial system.
 The relay connection to Telemail is through their host TELEMAIL/USA.
 The general syntax for Telemail addresses is
 "[USER/ORGANIZATION]HOST/COUNTRY", making the full address for the
 relay mailbox:
                    [INTERMAIL/USCISI]TELEMAIL/USA
 Users across the entire Telemail service can send mail to this
 address.  Users on the TELEMAIL host need only send to INTERMAIL.
 Internet users can use the basic Telemail format, append a
 "%TELEMAIL" to it, and mail to the resulting address as if it really
 existed on INTERMAIL.ISI.EDU, e.g.:
         [CWARD/USCISI]TELEMAIL/USA%TELEMAIL@INTERMAIL.ISI.EDU
 Note that the CMR system will accept anything before the "%TELEMAIL",
 that is, the CMR does not validate Telemail addresses before
 transmitting them to Telemail.
 The CMR handles Dialcom mail delivery in a similar way, but this
 system has what might be called "virtual hosts".  Groups can be set
 up with an alias system to allow easier intra-group access.  For
 example, both NSF and USDA share the same Dialcom host (157); but,
 while both groups send relay messages to Intermail, their actual
 fully qualified Dialcom mailboxes are different. For example, NSF's
 mailbox is NSF153, and USDA's mailbox is AGS9999.
 Mail going in either direction may use an embedded Simple Forwarding
 Header.  An SFH must be the first part of the message text.  It
 starts with a "Forward:"  field followed by a "To:" field.  "Cc:",
 "Subject:", and other fields may follow the "To:" fields. The SFH is
 terminated by a blank line.

Westine, DeSchon, Postel & Ward [Page 7] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 This is a template of an SFH:
    Forward: Destination-Network
    To: User@host1, User@host2,
         User2@host2
    Cc: User@host1
    Subject: This subject supercedes the subject in the host net header
    <Blank-Line>
 Dialcom syntax is "Host-ID:User-ID", for example, 134:ABC1234.  This
 format will work from any Dialcom host; but users in the same group
 as ABC would be able to use the user name, for example, JSMITH.
 Using the SFH format, mail to a Dialcom system could be sent as
 follows:
    To: Intermail@ISI.EDU
    Subject:  Test Message
    Forward: Compmail
    To: 134:ABC1234
    Here is the text of the message.
 Proper destination network names include ARPA, Telemail, Compmail,
 NSF-Mail, and USDA-Mail.
 It is possible for a user to make mistakes at many points in the
 process. Errors are handled as automatically as possible by the CMR.
 Many errors are caught in the standard Internet mail traffic, and
 users receive the usual error messages from the system.  Messages
 with incorrect commercial system addresses or faulty SFHs are also
 automatically returned to sender.  Messages that the software cannot
 handle are sent to the CMR's user-service mailbox, Intermail-
 Request@ISI.EDU.  This mailbox has been set up to take care of user
 problems and to be a central distribution point for user
 instructions.

PROBLEMS

 Several problems arise from the store-and-forward nature of the CMR.
 One of the biggest is that almost all of the commercial systems lack
 a machine-to-machine interface -- the CMR software must mimic a human
 user of the commercial system.  Another problem is that the Internet
 and a commercial system have different forms (or syntax) for
 electronic mail addresses.  A major goal of the CMR project is to
 make the link between networks as transparent as possible, allowing
 Internet users to use off-the-shelf mail programs.  Making commercial

Westine, DeSchon, Postel & Ward [Page 8] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 address formats fit the Internet standard is a major task [2].
 Compatibility with Internet addressing standards is also a concern.
 The commercial accounts are not able to take advantage of the
 transparency features of the Domain Name System (DNS) (see Appendix
 D); and some commercial addresses are incompatible with the Internet
 syntax--this requires Internet users to continue using the older
 methods.
 Another general problem to be solved is to reduce the amount of time
 needed to maintain the system.  Because most commercial systems force
 our software to mimic a human user, automatic error detection and
 handling are quite complex. The Intermail system requires human
 intervention in processing failed mail.  A goal of the CMR is to
 fully automate these processes.
 A related problem facing the CMR, as well as its predecessor
 Intermail, is the frequency with which commercial systems change
 their software.  The changes are usually minor and do not bother most
 human users; however, the CMR depends on being able to recognize
 certain strings.  To avoid the necessity of rebuilding the whole CMR
 when these strings change, most of the string markers are stored in
 ASCII files that are read at run time.
 The translation of commercial system addresses has created a new set
 of problems,  most of which are caused by the use of "special"
 characters by the commercial systems.
 Telemail uses square brackets ("[" and "]") around user names. While
 these characters are not special by Internet standards when found in
 the local part of an address, many (perhaps most) Internet mailers
 refuse to accept these characters unless they are quoted.  MMDF was
 modified locally to correct this.
 The square bracket problem is even worse for users of IBM mainframe
 machines, many of which are used on BITNET.  The square bracket is
 not a printable character on many BITNET IBM hosts, and all kinds of
 strange addresses can result from its use.
 The colon is another example.  Dialcom uses it as the delimiter
 between host and mailbox.  However, the colon is a special character
 in the Internet mail standard [2].  Users can avoid this problem by
 using the SFH and placing the Dialcom address at the beginning of the
 message text.  Although the CMR can accept addresses with colons,
 many Internet hosts and relays are unable to accept addresses that
 contain colons.  Mail with colons in the address fields is often
 rejected by Internet hosts and is returned to the Intermail-Request
 mailbox for error processing.  This can cause significant delays.

Westine, DeSchon, Postel & Ward [Page 9] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 Problems have also been caused by confusion about which hosts are
 mail relays between the Internet and other systems compatible with
 the Internet mail standard [2]. (e.g., BITNET, UUCP, and CSNET).
 When the CMR was implemented, a decision was made that the CMR would
 not keep track of these mail relays.  When a relay is changed, as the
 BITNET mail relays were in 1988, mail may be rejected because the
 host either no longer exists or refuses the mail.
 The mail relay problem is a subset of the larger problem of
 communicating information about new features and changes to the user
 community. Virtually none of the users of the CMR are local.  Many
 are hidden behind the veil of the commercial system.  (Dealing with
 commercial system customer support people has proven to be
 frustrating -- few of them seem to understand the concept of
 machine-to-machine exchanges.) Enhancements to commercial software
 that necessitate minor changes can disrupt some CMR users for days.
 Another problem that has not been adequately solved is validation of
 commercial system addresses and processing of failed commercial
 system mail.  The Telemail system will not validate a user/host
 combination until after the full text of the message has been
 transmitted.  If a long message is sent to an invalid address, it can
 be very expensive in terms of wasted time and connect charges.
 Telemail also gives inadequate information when the host is correct
 but the user name is not.  The failed mail notice received from
 Telemail is of little use to either a human reader or the CMR
 software.  The only information that Telemail returns is the message
 ID number -- it provides no subject, and no text to distinguish the
 message from the numerous others that pass through the mailbox.
 Dialcom does a better job of validating addresses.  If an address is
 not recognized, the system immediately prompts for a correction.  A
 simple <RETURN> will delete the invalid address from the list.
 The commercial systems are geared for paying customers to send and
 receive mail to other paying customers.  They are not equipped to
 handle reverse billing, or "collect calls."  ISI is currently charged
 for connect time needed to transmit and receive mail to and from
 other Internet sites.  A possible solution to this problem would be
 to extend the CMR. to include accounting and billing procedures that
 would pass the costs of CMR to its users.
 What had been GTE Telemail became Sprint SprintMail, Telenet became
 Sprintnet, and the host TELEMAIL/USA became SM66/USA.
 In April 1990, Sprint installed its X.400 implementation.  For the
 time being, the old-style Interconnect syntax will work. The CMR

Westine, DeSchon, Postel & Ward [Page 10] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 telemail channel and the Simple Forwarding Header (SFH) processor,
 were modified to accept either format in the SprintMail "From" field.
 Sprint uses the following syntax for X.400:
                    (O:USCISI,UN:INTERMAIL,TS:SM66)
 The SFH processor will "translate" this into:
               /O=USCISI/UN=INTERMAIL/TS=SM66/%TELEMAIL
 The channel program will reverse the process.  In the translation,
 parentheses become slashes, colons become equal signs and commas
 become slashes and vice versa.
 Unfortunately, the translation algorithm is not foolproof.  A
 Sprint/Internet relay did not use the same field names and values as
 those in SprintMail.  Consequently, a CMR translated address can not
 be sent unmodified to Sprint's relay, Sprint.COM, and Sprint.COM
 processed addresses cannot be sent unmodified to the CMR.
 From experimentation, the modifications necessary to a CMR processed
 address to make it acceptable to Sprint.COM are (1) take the "non-
 standard" X.400 fields of "UN" and "TS" and prepend "DD." to them,
 (2) add the country field and code (C:US) and (3) add the Telemail
 administrative domain name (ADMD:Telemail).  The above example would
 become:
  /O=USCISI/DD.UN=INTERMAIL/DD.TS=SM66/ADMD=TELEMAIL/C=US/@Sprint.COM
 The country code must be changed from "US" to "USA."  The CMR queue
 name must also be appended: "%TELEMAIL."
 The situation is further complicated by Sprint's decision to only
 relay mail to and from its own administrative domain.  Other X.400
 ADMDs may be added in the future if payment problems can be overcome.
 SprintMail encoded Internet addresses are not parsed correctly by the
 SFH processor, but that should not be a major problem -- who on the
 Internet is going to send to the commercial side of the relay?
 When the NSF decided to terminate NSFMAIL, it became clear that the
 CMR Project needed a way to get news out to the commercial users.
 The CMR channel programs now are able to append a news file to the
 end of messages going into the commercial networks.  After
 transmitting a message, each channel checks for a news file with the
 channel name and if present, sends it.

Westine, DeSchon, Postel & Ward [Page 11] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 The biggest costs of the CMR are the connect times to the Sprintnet
 X.25 network and the commercial machines.  Making the CMR transmit
 faster is the current number one problem.
 Three strategies are being pursued:
  1. Improve the implementation of the current method
  1. Change the method to take advantage of changes in the commercial

software

  1. Upgrade the modems and increase the number of phone lines
 For a list of known problems or bugs in the CMR software, see the
 Appendix of the program logic manual [6].

FUTURE DIRECTIONS

 No software project is ever completed, and the CMR is no exception.
 There are many possible extensions, some more difficult than others.
 One addition that will be made to the CMR is a channel for
 interacting with MCI Mail.  MCI Mail is one of the original TOPS-20
 commercial systems that were serviced by Intermail; the CMR will need
 to replace this function before all of the TOPS-20 machines are
 removed from service on the Internet.
 The adaptability of the CMR is such that adding new commercial
 systems should not be a major problem.  Additional commercial systems
 under consideration include General Electric's GENIE, Western Union's
 EasyLink, and Compuserve.
 One possible addition to the CMR system could be maintenance of a
 list of gateways.  This would allow commercial system users to
 incorporate the native address formats of other networks into the
 SFHs.  An advantage of this would be that users could simply tell the
 CMR to forward a message to BITNET, for example, and the CMR would
 find the gateway and properly format the address for that gateway.
 To increase the ease of use to Internet users, the system might treat
 each commercial system as an Internet host and create DNS database
 records for them.  This would allow users to send mail to a non-
 Internet user at an Internet-style domain name.
 Another improvement would be the possibility of accepting X.400-style
 addressing. The current system rejects them.

Westine, DeSchon, Postel & Ward [Page 12] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 In order to further reduce the hazards of string changes in the
 commercial system software, an AI component could be added to the
 commercial system interfaces.  Such an AI component might be able to
 "figure out" what marker a new prompt represents and to remember it.

ACCESS INFORMATION

 For instructions on how to use Intermail and CMR contact Intermail-
 Request@ISI.EDU.

REFERENCES

 [1]  Cohen, D., "A Suggestion for Internet Message Forwarding for
      MOSIS", IEN-180, USC/Information Sciences Institute, March 1981.
 [2]  Crocker, D., "Standard for the Format of ARPA Internet Text
      Messages", RFC-822, University of Delaware, August 1982.
 [3]  DeSchon, A. L., "MCI Mail/ARPA Mail Forwarding", USC/Information
      Sciences Institute, ISI Research Report, RR-84-141, August 1984.
 [4]  DeSchon, A. L., "INTERMAIL, An Experimental Mail Forwarding
      System", USC/Information Sciences Institute, ISI Research
      Report, RR-85-158, September 1985.
 [5]  Kingston, D., "MMDF II: A Technical Review", Usenix Conference,
      Salt Lake City, August 1984.
 [6]  Ward, C. E., "The Commercial Mail Relay Project:  Intermail on
      UNIX", USC/Information Sciences Institute, 1988.

Westine, DeSchon, Postel & Ward [Page 13] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

APPENDIX A

 The Internet and Connected Networks
 The Internet is a network of networks interconnected by gateways or
 routers. The common element is the TCP/IP protocol suite.  The
 Internet now includes approximately 800 networks and 100,000 host
 computers.  The Internet is made up of local area networks in
 research institutes and university campuses, regional networks, and
 long-haul networks.  These resources are supported by the using
 organizations and by several US goverment agencies (including DARPA,
 NSF, NASA, DOE, and NIH).   The long-haul networks in the Internet
 are the ARPANET, the MILNET, the NSFNET Backbone, the NASA Science
 Internet (NSI), and the DOE Energy Science Network (ESNET).
 Other systems using TCP/IP or other protocols may be networks of
 networks or "internets" with a lower case "i".  The capital "I"
 Internet is the one described above.
 There are other networks with (semi-) compatible electronic mail
 systems. These include BITNET (and EARN and NETNORTH), UUCP (and
 EUNET), CSNET, ACSNET, and JANET.  Users of electronic mail may not
 necessarily be aware of the boundaries between these systems and the
 Internet.
 The Domain Name System (DNS) is a mechanism used in the Internet for
 translating names of host computers into addresses.  The DNS also
 allows host computers not directly on the Internet to have registered
 names in the same style.
 BITNET (Because It's Time NETwork)
 BITNET has about 2,500 host computers, primarily at universities, in
 many countries.  It is managed by EDUCOM, which provides
 administrative support and information services.  There are three
 main constituents of the network: BITNET in the United States and
 Mexico, NETNORTH in Canada, and EARN in Europe.  There are also
 AsiaNet, in Japan, and connections in South America.  Gateways exist
 between BITNET and the Internet.  The most common gateway used is
 CUNYVM.CUNY.EDU.
 CSNET (The Computer + Science Network)
 CSNET has 180 member organizations, primarily computer science
 research laboratories at universities and research institutes,
 including international affiliates in more than a dozen countries.
 CSNET has adopted DNS-style names for all its host computers.  It is
 administered by the University Corporation for Atmospheric Research

Westine, DeSchon, Postel & Ward [Page 14] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

 (UCAR) and provides administrative support and information services
 via the CSNET Information Center (CIC) at Bolt Beranek and Newman
 (BBN). The gateway between CSNET and the Internet is RELAY.CS.NET.
 Note: CSNET and BITNET have officially merged into a single
 organization as of October 1, 1989.
 UUCP (UNIX to UNIX Copy)
 UUCP is a protocol, a set of files, and a set of commands for copying
 data files from one UNIX machine to another.  These procedures are
 widely used to implement a hop-by-hop electronic mail system.  This
 simple mechanism allows any UNIX host computer to join the system by
 arranging a connection (dial-up or permanent) with any UNIX host
 already in the system.  In the basic UUCP system, mail is source
 routed by the sending user through a path of connected hosts to the
 destination.  Currently, there are databases of connection
 information (UUCP maps) and programs (pathalias) that aid in
 determining routes.  There is some use of DNS-style names by UUCP
 hosts.  EUNET is a UUCP-based network in Europe, and JUNET is a
 similar net in Japan.  These international branches of UUCP use DNS-
 style names as well.  There are many hosts that may relay mail
 between UUCP and the Internet.  One prominent gateway is
 UUNET.UU.NET.
 JANET (Joint Academic NETwork)
 JANET is the primary academic network in the United Kingdom, linking
 about 1,000 computers at about 100 universities and research
 institutes.  JANET has a domain name system similar to that of the
 Internet, but the order of the domain name parts is opposite (with
 the top-level domain on the left).  The protocols used in JANET are
 the UK "Coloured Books".  The primary gateway between JANET and the
 Internet is NSFNET-RELAY.AC.UK.
 ACSNET (Australian Computer Science Network)
 ACSNET is the principal electronic mail system for the computer
 science and academic research community in Australia, connecting
 about 300 sites.  It works similarly to UUCP.  ACSNET has a domain
 naming syntax similar to that for Internet domains.  The gateways
 between ACSNET and the Internet are MUNNARI.OZ.AU and UUNET.UU.NET.

APPENDIX B

                       <<< Mail Systems Map >>>

Westine, DeSchon, Postel & Ward [Page 15] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

APPENDIX C

 March 1990      sent    read    total
 Telemail        1291    768     2059
 MCI Mail        56      44      100
 Compmail        634     306     940
 NSF-Mail        370     243     613
 CGnet           171     82      253
 USDA Mail       6       1       7
 BellSouth       6       10      16
 Other           0       0       0
 Total           2534    1454    3988
 Days in Month   31
 Messages per Day        128.65
 April 1990      sent    read    total
 Telemail        1363    696     2059
 MCI Mail        40      39      79
 Compmail        771     329     1100
 CGnet           361     191     552
 USDA Mail       28      31      59
 BellSouth       98      73      17
 Other           0       0       0
 Total           2661    1361    4022
 Days in Month   30
 Messages per Day        134.07
 May 1990        sent    read    total
 Telemail        1007    561     1568
 MCI Mail        23      12      35
 Compmail        815     359     1174
 CGnet           406     210     616
 USDA Mail       12      5       17
 BellSouth       167     93      260
 Other           0       0       0
 Total           2430    1240    3670
 Days in Month   31
 Messages per Day        118.39

Westine, DeSchon, Postel & Ward [Page 16] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

APPENDIX D

 The Domain Name System
 The Domain Name System (DNS) provides for the translation between
 host names and addresses.   Within the Internet, this means
 translating from a name, such as "ABC.ISI.EDU", to an IP address such
 as "128.9.0.123".  The DNS is a set of protocols and databases.  The
 protocols define the syntax and semantics for a query language to ask
 questions about information located by DNS-style names. The databases
 are distributed and replicated.  There is no dependence on a single
 central server, and each part of the database is provided in at least
 two servers.
 In addition to translating names to addresses for hosts that are in
 the Internet, the DNS provides for registering DNS-style names for
 other hosts reachable (via electronic mail) through gateways or mail
 relays.  The records for such name registration point to an Internet
 host (one with an IP address) that acts as a mail forwarder for the
 registered host.  For example, the Australian host "YARRA.OZ.AU" is
 registered in the DNS with a pointer to the mail relay
 "UUNET.UU.NET".  This gives electronic mail users a uniform mail
 addressing syntax and avoids making them aware of the underlying
 network boundaries.

Westine, DeSchon, Postel & Ward [Page 17] RFC 1168 Intermail and Commercial Mail Relay Services July 1990

SECURITY CONSIDERATIONS

 Security issues are not discussed in this memo.

AUTHORS' ADDRESSES

 Ann Westine
 USC/Information Sciences Instutite
 4676 Admiralty Way
 Marina del Rey, CA  90292-6695
 Phone:  (213) 822-1511
 EMail:  Westine@ISI.EDU
 Annette DeSchon
 USC/Information Sciences Instutite
 4676 Admiralty Way
 Marina del Rey, CA  90292-6695
 Phone:  (213) 822-1511
 EMail:  DeSchon@ISI.EDU
 Jon Postel
 USC/Information Sciences Instutite
 4676 Admiralty Way
 Marina del Rey, CA  90292-6695
 Phone:  (213) 822-1511
 EMail:  Postel@ISI.EDU
 Craig E. Ward
 USC/Information Sciences Instutite
 4676 Admiralty Way
 Marina del Rey, CA  90292-6695
 Phone:  (213) 822-1511
 EMail:  Ward@ISI.EDU

Westine, DeSchon, Postel & Ward [Page 18]

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