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Network Working Group                                         A. WestineRequest for Comments: 1168                                    A. DeSchon                                                               J. Postel                                                               C.E. Ward                                                                 USC/ISI                                                               July 1990INTERMAIL AND COMMERCIAL MAIL RELAY SERVICESSTATUS 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 (seeAppendix 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 (seeAppendix 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 1990DESCRIPTION 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.  SeeAppendix 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 TelemailWestine, DeSchon, Postel & Ward                                 [Page 5]

RFC 1168      Intermail and Commercial Mail Relay Services     July 1990ACCEPTABLE 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 commercialWestine, 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) (seeAppendixD); 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 CMRWestine, 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:      - 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                                [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 1990APPENDIX 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 ResearchWestine, 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 1990APPENDIX 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        118.39Westine, DeSchon, Postel & Ward                                [Page 16]

RFC 1168      Intermail and Commercial Mail Relay Services     July 1990APPENDIX 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 1990SECURITY 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.EDUWestine, DeSchon, Postel & Ward                                [Page 18]