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

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

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

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 "[email protected]".

         <<< 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

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

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

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%[email protected]

  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

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: [email protected]
     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-
  [email protected].  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

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

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

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

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:

     - Improve the implementation of the current method

     - Change the method to take advantage of changes in the commercial
       software

     - 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

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-
  [email protected].

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

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

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

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

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

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:  [email protected]

  Annette DeSchon
  USC/Information Sciences Instutite
  4676 Admiralty Way
  Marina del Rey, CA  90292-6695

  Phone:  (213) 822-1511
  EMail:  [email protected]

  Jon Postel
  USC/Information Sciences Instutite
  4676 Admiralty Way
  Marina del Rey, CA  90292-6695

  Phone:  (213) 822-1511
  EMail:  [email protected]

  Craig E. Ward
  USC/Information Sciences Instutite
  4676 Admiralty Way
  Marina del Rey, CA  90292-6695

  Phone:  (213) 822-1511
  EMail:  [email protected]

Westine, DeSchon, Postel & Ward