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RFC1168 - Intermail and Commercial Mail Relay services

王朝other·作者佚名  2008-05-31
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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 RFCdiscusses 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 RFCprovides

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.

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].

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.

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.

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

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.

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.

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

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.

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

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.

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.

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.

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

(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 >>>

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

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.

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

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