Syracuse University Electronic-Mail Consultant's Guide John M. Wobus Communications & Development Computing & Network Services Syracuse University June 29, 1989 Document Number: CGMAIL-1 (c) Syracuse University Computing & Network Services 1989. Copying, in whole or in part, is permitted only for educational purposes and copies must include this copyright notice. Copying or republishing for commercial advantage is prohibited. For per- mission to republish or distribute, write to: Director of Com- puting & Network Services, Syracuse University, Skytop Office Building, Syracuse NY 13244. ABSTRACT This guide provides a lot of background information for solv- ing electronic-mail problems at Syracuse University. It includes an overview of the world of electronic mail among colleges and universities, describes idiosyncracies of networks and systems available at Syracuse University and provides an extensive glos- sary of terms peculiar to college and university electronic mail. Abstract ii PREFACE Electronic mail among universities is a babel. There are many different electronic-mail networks that serve universities, most of which are interconnected forming an enormous "network of net- works" which no one completely understands. If a user gives another user his or her electronic-mail address, it may be obvi- ous how to send a message, but it may not. Various computers cannot reach other computers, but often they can in non-obvious ways. Most university people send electronic mail to few other sites. If some of these sites are on networks requiring special addresses, then the sender either must learn something about how electronic mail is delivered or must seek the advice of someone who does. The aim of this guide is to serve as an overview and as a reference for people who are often faced with these prob- lems. It gives a brief overview of electronic mail and offers definitions of many terms one may come across. It serves as a companion to [5], which is a "bag of tricks" for reaching various mail networks. Syracuse University Electronic-Mail Consultant's Guide iii CONTENTS Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . ii Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 1 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . 1 This document . . . . . . . . . . . . . . . . . . . . . . . 2 Overview of World-Wide Electronic Mail . . . . . . . . . . . . 3 Format of Messages . . . . . . . . . . . . . . . . . . . . . . 5 Address Formats . . . . . . . . . . . . . . . . . . . . . . 7 "Routing" or "Forwarding" Mail . . . . . . . . . . . . . 8 Qualifiers . . . . . . . . . . . . . . . . . . . . . . . 9 Mail Transfer Agents . . . . . . . . . . . . . . . . . . . . 11 Internet Mail . . . . . . . . . . . . . . . . . . . . . . . . 13 Qualifiers . . . . . . . . . . . . . . . . . . . . . . . . 14 Mail Exchangers . . . . . . . . . . . . . . . . . . . . . 15 Reaching Sites off the Internet . . . . . . . . . . . . . 16 What Can Your Computer Reach? . . . . . . . . . . . . . . 16 BITNET Mail . . . . . . . . . . . . . . . . . . . . . . . . . 18 The Columbia MAILER . . . . . . . . . . . . . . . . . . . 19 Qualifiers and Domains . . . . . . . . . . . . . . . . . . 20 Reaching Sites off BITNET . . . . . . . . . . . . . . . . 21 What Can Your Computer Reach? . . . . . . . . . . . . . . 21 Systems at Syracuse University . . . . . . . . . . . . . . . 22 IBM PCs, Compatibles, & Macintoshes . . . . . . . . . . . 22 ICARUS . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Public Workstation Cluster . . . . . . . . . . . . . . . . 23 RODAN . . . . . . . . . . . . . . . . . . . . . . . . . . 23 SUAIS . . . . . . . . . . . . . . . . . . . . . . . . . . 23 SUMVS . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Sun Workstations . . . . . . . . . . . . . . . . . . . . . 24 SUNRISE . . . . . . . . . . . . . . . . . . . . . . . . . 24 SUVM . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Unix Systems . . . . . . . . . . . . . . . . . . . . . . . 25 VMS Systems . . . . . . . . . . . . . . . . . . . . . . . 25 The Easiest Way to Reach Nearly Anywhere . . . . . . . . . . 26 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . 33 Contents iv Appendix A: Electronic Mailing Lists . . . . . . . . . . . . 34 Subscribing and Cancelling Subscriptions . . . . . . . . . 34 Finding Out About Lists . . . . . . . . . . . . . . . . . 36 Syracuse University Electronic-Mail Consultant's Guide v INTRODUCTION Electronic mail is the exchange of messages between people through a computer or computers joined by computer network. The sender enters a message and an electronic-mail address. If the recipient is on the same computer, then the mail software simply stores the message where the recipient can read it. If the sender and recipient are on different computers, then the mail must be transferred through a data-communications net- work from one computer to the other before it is stored for the recipient. If the computers are not on the same network, then the message must first be delivered to a computer which can move it from one network to the other (an electronic-mail gateway). If there is not a gateway joining the sender's and recipient's networks, then the message might have to pass through intervening networks using more gateways. And, of course, there are separate groups of networks which share no gateways, so mail cannot be delivered from one to the other. Among the world-community of universities and colleges, there are a surprising number of net- works which are interconnected allowing thousands of institutions to exchange electronic mail. PROBLEMS There is no universal way of addressing an electronic message. Different data-communications networks are incompatible, having been developed by different groups of people, each using their own hardware and software. Typically, each type of network has its own way of addressing messages. If a colleague tells you his or her electronic-mail address, it is likely to work if you are both on the same network and the same type of computer. If not, you might have to modify the address in order to make it work. The rules for modifying addresses are as diverse as the different networks and computers that make up our world-wide collection of networks. If you are lucky, the electronic-mail software that you are using to send the mail might do this address manipulation for you (i.e., it might have some of these rules programmed in it). This greatly simplifies sending some mail, but no program incorporates all the rules (things change too quickly) and you may even find that you need to compensate for your mail program's manipulations as you try to figure out how to create a workable address. The ability to build addresses thus requires some knowledge of the software that handles electronic mail from your computer to each of the networks you need to reach. Syracuse University Electronic-Mail Consultant's Guide 1 THIS DOCUMENT This document provides you with background information for solving electronic-mail problems. Specific "tricks" are recorded in another document, [5], which is separate so it can be kept up-to-date. This document starts with an overview of the "world of university electronic mail", describes the format used for most electronic mail, describes the idiosyncracies of the systems and the electronic-mail networks that serve Syracuse University, lists a procedure for sending electronic mail nearly anywhere, and finishes with an extensive glossary giving explanations of specialized terms as well as various electronic-mail networks and programs. Introduction 2 OVERVIEW OF WORLD-WIDE ELECTRONIC MAIL Colleges, universities, and other research institutions have developed cooperative electronic-mail networks that span sites throughout the United States and beyond. Large (multi-user) com- puters, typically administered by the "computing services" department or individual academic departments are tied together by LANs, network gateways, and leased telephone lines. The com- puters are assigned names and "electronic-mail addresses" of the users are formed (according to explicit rules) out of the name of the computer and the "username" or "sign-on name" of the individ- ual user. The computers offer their users a program or programs to enter and read the messages. Furthermore, the major cooperative electronic-mail networks have been interconnected by "electronic-mail gateways", computers which are attached to more than one of these networks and trans- fer electronic mail back and forth between them. The gateways typically require extra information to be included in the message to direct it first, to the gateway, and then tell the gateway where to send it on. On many computers, software for entering and sending electronic mail has been enhanced to direct mail through the gateways. On some others, alternative programs have been developed to do this. The result of all this is a giant "network of networks" which serves many thousands of computers at thousands of institutions, serving at least a million people at these institutions. How- ever, because any participating institution is free to add a gateway to yet another network, no one really knows how to reach all possible destinations or how large the network-of-networks is. For example, many corporate networks are tied through gate- ways, but very often, the gateway to a corporate network has deliberate, software-implemented restrictions to help the corpo- ration control such things as dissemination of trade secrets, marketing strategy, or statements on the parts of individuals that could be mistaken for corporate positions. The main electronic-mail networks used to transfer electronic mail among colleges, universities, and other research institu- tions are BITNET (which includes "BITNET-proper" as well as NETNORTH and EARN), the UUCP network, CSNET, and the Internet (which includes ARPANET as well as NSFnet and all its regional networks). All these and more are tied together with gateways. Among the other networks tied together are similar, but smaller or more specialized networks, corporate networks, commercial net- works, and networks serving other countries or other regions of the world. Networks that are deliberately kept separate include commercial networks (who may be trying to avoid encouraging "cooperative" electronic mail when they are trying to sell such a service), corporate networks, and classified military networks. Syracuse University Electronic-Mail Consultant's Guide 3 Syracuse University is a member of BITNET and NYSERNet (a part of the Internet), and has software to facilitate the delivery of mail to all the networks named above as well as others. Thus we will discuss BITNET and the Internet at length. Numerous other networks are briefly described in the glossary. Overview of World-Wide Electronic Mail 4 FORMAT OF MESSAGES The most common message format is commonly known as RFC822 and is defined in [2]. It is the official format for the Internet and a variant of it is the most common format for messages on BITNET. It makes an electronic message look something like a memo (with lines at the top labeled "To:", "Date:", etc.) but has an exact definition so that software can be written to help manipulate such messages. In this section, we will give an over- view of RFC822 format. For a complete explanation, consult [2]. RFC822 format divides messages into two overall sections: "message header" and the "message body". They are separated by the first "empty" line in the message. The message body (after this empty line) can contain anything. The message header is strictly defined. Each line in the header either starts with a label (a word followed by a colon, such as "Date:") or is a con- tinuation of a line that does, in which case it starts with one or more "blank" characters. We will ignore continuation lines in the rest of our explanation of the header--just remember that any line in the header may be continued. A legal RFC822 header must have at least three lines: a "Date" line, a "From" line, and a destination line marked by "To", "cc", or "bcc". They may be in any order as may all the lines of the header. The date is nearly exactly specified, but you will often see mail with illegal date formats. RFC822's exacting specification of the date format is helpful: it lets programs sort messages according to the date, for example. The "From" and destination lines hold electronic-mail addresses of the sender and recipient of the message. We will discuss the format of such addresses in more detail below. +---------------------------------------------------------------+ | Date: 21 Jun 89 13:18:04 DST | | From: mmroe@suvm | | To: jjdoe@suvm | | | | Hi. | | | | Figure 1: Example RFC822 message: at its simplest. | +---------------------------------------------------------------+ The destination line may hold a list of addresses, separated by commas. There are numerous additional "optional" lines which may be in the header. Some of these are: Syracuse University Electronic-Mail Consultant's Guide 5 Sender Holds the address of a person (or program) who sent this message on behalf of the person whose address is listed in the "From" line. Reply-to Holds the address which should receive the reply. It is unnecessary if replies should be sent to the address listed in the "From" line. Subject Holds a word, phrase, or sentence for the convenience of the sender and recipient. It is intended to hold a summary or describe the nature of the message. Resent-? When you send a message that you receive on to another person, this may be marked in the header by simply add- ing three lines: "Resent-to:", "Resent-from:", and "Resent-date:". Unfortunately, they are not well defined; for example, there is not complete agreement about what to do when the message is re-sent yet another time. In-Reply-To: Holds something to identify the message you are reply- ing to. It may be, but is not necessarily a Message- ID. The following lines are usually added to the header as it is transferred through intervening computers and finally delivered: Return-path Holds an address which will reach the sender, as deter- mined by the intervening computers that delivered the mail. Received Holds information about a mail system (mail transfer agents) that relayed the message. Message-ID Holds an identification string assigned to the message by the sending computer. Comments Holds text (like the subject). It is intended to allow the addition of a small amount of additional text to the message without disturbing the message body. There are some other lines used less often. If you want to invent your own, lines beginning with an "X-" are set aside for that purpose. Here is an example message-header with lots of lines: Format of Messages 6 +---------------------------------------------------------------+ | Return-Path: | | Received: from ucbarpa.Berkeley.EDU | | by jade.berkeley.edu (5.61.1/1.16.22) | | id AA24755; Wed, 21 Jun 89 20:31:44 PDT | | Received: from RELAY.CS.NET by ucbarpa.Berkeley.EDU | | id AA01355; Wed, 21 Jun 89 19:58:14 -0700 | | Received: from dg-rtp.dg.com by RELAY.CS.NET | | id aa10152; 21 Jun 89 17:36 EDT | | Received: from rtp46.rtp.dg.com (rtp46) by dg-rtp.dg.com | | id AA03542; Wed, 21 Jun 89 17:16:43 edt via SMTP | | Received: by rtp46.rtp.dg.com (1.00/4.7) | | id AA13489; Wed, 21 Jun 89 17:17:32 edt | | From: Lynn Smith | | Message-Id: <8906212117.AA13489@rtp46.rtp.dg.com> | | Subject: Billings and the rest of the world | | To: info-billings@ucbarpa.Berkeley.EDU | | Date: Wed, 21 Jun 89 17:17:28 EDT | | Cc: Mark Ditroff | | X-Mailer: ELM [version 2.2 PL0] | | | | Figure 2: Example of a long message header. | +---------------------------------------------------------------+ ADDRESS FORMATS A "From:", "Sender:", "Reply-to:", or "Return-path:" field has an electronic-mail address in a style defined by RFC822. A "To:", "cc:", or "bcc:" field holds one such address or a list of such addresses, separated by commas. In this section, we will describe this format. Given a computer with the name "SUVM" and a username of "MMROE", here are some examples of the address that demonstrate the legal formats: +---------------------------------------------------------------+ | MMROE@SUVM | | MMROE@suvm | | Mary Roe | | Mary M Roe | | "Mary M. Roe" | | MMROE@SUVM (Mary M. Roe) | | | | Figure 3: Example RFC822 addresses. | +---------------------------------------------------------------+ The basis of all the formats is the username and the computer's name joined with an "at" sign (@) between. Some other relevant points: Syracuse University Electronic-Mail Consultant's Guide 7 * The receiving computer is allowed to distinguish usernames by case so the case of its letters must be preserved. Many types of computers ignore the case, so mail-sending programs that ignore this stricture work a large percentage of the time. * Angle brackets (<>) may be placed around the address. Any words placed before the angle brackets are ignored by the software but mail software should keep them intact and they may be inserted for the benefit of the recipient. * Quoted strings using double quotes (") may also be placed before the angle brackets. * Pairs of parenthesis () mark the beginning and end of "com- ments" within the header line. They may be used within addresses. Following are some addresses with problems: +---------------------------------------------------------------+ | Mary M. Roe | | Mary Roe, 443-9999 | | | | Figure 4: Example bad RFC822 addresses. | +---------------------------------------------------------------+ * Words, numbers, and quoted strings may be placed before the angle-bracketed address. Other, "special" characters may not. Much software will ignore a period, but commas are used to separate addresses in address lists, and any mail software will fail trying to interpret whatever comes before the comma as a separate address. Ideally, the software used to compose and send the message would take care of making sure the addresses are correct, but this is not always the case. "Routing" or "Forwarding" Mail It is often necessary for the sender to "route" mail: if the computer that you are sending from cannot send directly to the recipient's computer, perhaps there is a third computer which can receive from yours, can send to your recipients, and will inter- pret certain address forms as instructions to forward the mes- sage. These are also referred to as "in-care-of" addresses: you are sending the mail to an address "in care of" another computer. Here are some example forms: Format of Messages 8 +---------------------------------------------------------------+ | jjdoe%farnode@icarus | | farnode!jjdoe@icarus | | @icarus:jjdoe@farnode | | | | Figure 5: Example addresses that forward mail. | +---------------------------------------------------------------+ These each direct mail first to ICARUS, asking ICARUS to forward the mail to jjdoe@FARNODE. Some points: * Though RFC822 allows the use of percent (%) or exclamation point (!) in usernames, any special interpretation (i.e., forwarding) is left up to the receiving system. In other words, this is not an RFC822 rule; it is a convention which RFC822 allows. Many systems, particularly Unix systems, interpret the percent sign this way, but this is no RFC822 requirement. The use of the exclamation point is less uni- versal, and is used mainly to forward to certain types of networks (UUCP networks). * The use of the additional at-sign (@) and colon (:) is the method for forwarding mail specified by RFC822, but it is not universally implemented. An example of an illegal way to specify forwarding is: +---------------------------------------------------------------+ | jjdoe@farnode@icarus | | | | Figure 6: Example of illegal address. | +---------------------------------------------------------------+ In fact, the predecessor to RFC822 allowed this and much software still interprets it as you might expect. Qualifiers Our discussion has ignored qualifiers, which are extra words appended to the end of the name of the computer, joined to it with an intervening period (.). Syracuse University Electronic-Mail Consultant's Guide 9 +---------------------------------------------------------------+ | icarus.cns.syr.edu | | | | Figure 7: The name of a computer with qualifiers. | +---------------------------------------------------------------+ RFC822 defines them, but says nothing about how they are used. They are simply part of the name of the computer as far as RFC822 is concerned. Networks that utilize RFC822 for the transmission of mail have their own definitions of what the qualifiers mean. We will discuss qualifiers in the discussion of Internet and BITNET mail. Format of Messages 10 MAIL TRANSFER AGENTS In our discussion of RFC822 format, we brought up the term mail transfer agent with no explanation. The function of compos- ing and sending a message is often divided into composing the message (entering and editing it), and the actual sending. A program which does the latter is called a mail transfer agent. This division of function is motivated by the fact that a sepa- rate mail transfer agent is often designed to do more than simply send outgoing messages. Other typical capabilities include: * Inspecting incoming mail, interpreting in-care-of addresses and resending the mail on accordingly. * Inspecting the destination addresses of outgoing mail and using special procedures to route it if necessary. For example, the mail transfer agent might be programmed to rec- ognize addresses on some other electronic-mail network and route the message through a gateway to that network. This might require rewriting the destination address as an in-care-of address or it might require further manipulation of the mes- sage.(1) * Acting as gateways between different electronic-mail net- works. A single mail transfer agent can do the same task for two different electronic-mail networks. This puts it in the position to move mail from one network to the other. A related task is that the mail transfer agent may be programmed to rewrite all the addresses in each copy of the message sent so that the recipient can use any of the addresses. Following is an example demonstrating this process: +---------------------------------------------------------------+ | To: mmroe%finalc@ournode | | From: jjdoe@firstc | | | | Figure 8: Example To: and From: fields. | +---------------------------------------------------------------+ --------------------- (1) Such rewriting of addresses in the header by the mail trans- fer agent is sometimes called "munging" them. Syracuse University Electronic-Mail Consultant's Guide 11 +---------------------------------------------------------------+ | To: mmroe@finalc | | From: jjdoe%firstc@ournode | | | | Figure 9: Example of To: and From: fields after rewriting. | +---------------------------------------------------------------+ This example shows how the computer OURNODE's mail transfer agent rewrites the header fields as it forwards the message. By rewriting the "From:" field as an in-care-of address, it gives the recipient an address which will route MMROE's answer back through OURNODE. This is very helpful if the computers FIRSTC and FINALC cannot exchange mail directly which is presumably the reason why the original message was routed through OURNODE. An example of this is the case where the two computers are on dif- ferent networks. Some examples of mail transfer agents are Sendmail on Unix, PMDF on VAX/VMS, and IBM's SMTP program on VM/CMS. Mail Transfer Agents 12 INTERNET MAIL The Internet is a world-wide network made up of hundreds of interconnected smaller networks acting cooperatively. It includes university campus networks, nation-wide networks, regional networks, corporate networks, and government networks, all operating at different speeds. They all use a common proto- col (TCP/IP) which is designed to make connected networks act as one large network. For example, to sign on to a computer at another university that's on that university's network, one needs only that computer's official "Internet" name. Routing the data to and from that computer through any number of intervening net- works is handled automatically. The Internet started with ARPANET, but has since grown to where ARPANET is only a small part of it.(2) The Internet now includes MILNET, Wideband, ESNet, DRI, NSFnet, various campus networks of universities and other research institutions, various corporate networks, and various networks serving other countries. NSFnet includes the NSFnet "backbone" (a network linking about 13 sites across the continental United States) as well as several networks serving regions of the country or certain important sites. These include BARRNet, CICnet, JVNCNET, Merit, MIDNET, MRNET, NCSANET, NorthwestNet, NYSERNet, PSCNET, SDSCNET, SESQUINET, SURANET, USAN, and WESTNET. Electronic mail from one computer on the Internet to another is generally transmitted directly from the sender's computer to the recipient's computer. More specifically, the sending comput- er sends a query to the receiving computer to see if it is ready to receive a message. If so, it sends the beginning of the mes- sage, waiting for the receiving computer to request more. The two computers continue to send the message, piece by piece until the receiving computer sends an "acknowledgement" that it has received the entire message. If the sending computer does not receive this acknowledgement, it waits a while and tries again. Here are some consequences of this method: * The message is only transmitted if both the sending and receiving computers as well as the entire intervening network are working for a sufficiently long time to transfer the mes- sage. * The length of time necessary to transfer a message depends upon the speed at which the network transmits data as well as the speed at which the computers carry out their sending and requesting operations. These, in turn, depend upon network and computer load. A message may end up waiting until night time to be delivered simply because that is when the loads go down to the point where it can get through. --------------------- (2) ARPANET is currently in the process of being disassembled. Syracuse University Electronic-Mail Consultant's Guide 13 * The message takes up space on the sending computer until it is delivered. * Should the network or receiving computer lose the final acknowledgement, then the message will be duplicated: the receiving computer does not later realize that the next try is really the message that it has already received. This should be rare, but does happen and some circumstances exa- cerbate the problem. * As long as the message is waiting, the sending computer uses up a bit of computer time and network capacity trying to send it. Thus a computer that normally receives mail but is turned off is wasting computer and network resources. If a message is directed to a list of recipients including two or more recipients on the same receiving computer, then only one copy of the message needs to be transmitted to the receiving com- puter. QUALIFIERS Qualifiers (as described in the section on the format of electronic-mail addresses) are used on the Internet to designate a heirarchical organization of all the computer names. The final two qualifiers of the official Internet name of a computer desig- nate the institution which owns it. For example, names ending with ".syr.edu" belong to Syracuse University whereas those end- ing with ".hp.com" belong to the Hewlett-Packard corporation. These pairs are assigned to the institution by a central adminis- tration for the Internet. Of these two, the very last qualifier designates the type of institution or the location by country.(3) Following are some of the final qualifiers used on the Internet: edu designates an educational institution. com designates a commercial institution. mil designates a military institution. gov designates a non-military government institution. net designates an institution which provides networking services. org designates other institutions such as non-profit insti- tutions. --------------------- (3) Originally, all final qualifiers designated the type of institution, but as networks in other countries were added to the Internet, some countries wanted a set of names of their own to administer. Internet Mail 14 us designates an institution in the United States. Cur- rent practice is to use this for certain small institu- tions. ca designates an institution in Canada. Use of qualifiers before these last two are left to the insti- tution. They may be used by the institution to divide the names between departments as Syracuse University does (for example, ".cis.syr.edu" designates a name belonging to the School of Com- puting and Information Science). Thus qualifiers define "sets" of names whose administration may be delegated heirarchically. These sets are called "domains" and such a set is usually designated by its string of qualifiers, so, for example, we may speak of the "syr.edu domain", which is the set of all names that end with ".syr.edu". It is important to note that as far as the Internet is con- cerned, the qualifiers are part of its name for the computer. The responsibility for supplying any qualifiers to make the user's task easier belongs to the software on the sending comput- er. MAIL EXCHANGERS The Internet supports the idea of "mail exchangers", computers which receive mail for other computers. Essentially, this is an automated method by which mail for one computer is sent in care of another: if "computer A" is the designated mail exchanger for "computer B", then any computer sending mail addressed to "com- puter B" should send the mail to "computer A" instead, which should be set up to deliver the mail properly. This facility is useful for various purposes: * If a computer is down a lot of the time, another computer, which is up more often, can be its designated mail exchanger, thereby collecting mail for it from throughout the world. The mail exchanger would be set up to deliver the mail to the receiving computer when it is up again. This is a courtesy to the sending computer which does not have to waste so much time trying to deliver the message and to the users of the Internet since it reduces network load for the failed attempts. * A computer which is not on the Internet at all can be given an Internet name. The mail can be delivered by giving it a mail exchanger: a computer which does reside on the Internet and which can deliver the mail, presumably through an entire- ly different network. There are a couple of other useful features of mail exchangers: Syracuse University Electronic-Mail Consultant's Guide 15 * A computer may have several designated mail exchangers which are prioritized. A sending computer can then try the mail exchanger with the highest priority first, then try another if that computer is down. This allows one to give mail a chance to make its first step across the Internet if any of several computers are running. * A mail exchanger can be designated for an entire domain of names. This can direct all mail addressed to an entire institution to a single mail exchanger (or prioritized list of mail exchangers), or can be used to make an entire network which is not part of the Internet appear to be part of it, for the purposes addressing electronic mail. REACHING SITES OFF THE INTERNET Computers on the Internet may send to numerous sites off the Internet through three mechanisms: * Mail exchangers. * Special interpretation of addresses by the mail transfer agent. * Explicit in-care-of addressing. Numerous domains have been established (using single mail exchan- gers for entire domains) to handle networks associated with vari- ous countries of the world, to make them appear to be part of the Internet as far as electronic mail is concerned. See [5] for some examples. BITNET is an example of a network which is not handled by mail exchanger. Many computers on the Internet support the qualifier ".bitnet", sending the mail to an appropriate gateway through configuration of the mail transfer agent. WHAT CAN YOUR COMPUTER REACH? Unfortunately, not all software on the Internet is capable of delivering electronic mail to all Internet computers. The gener- al reason for this is that the rules for deciding where to send electronic mail have been enhanced since the beginnings of the Internet and not all software is up-to-date. Following are some of the problems plaguing some Internet computers: * Many Internet computers still use an old system of looking up the name of a computer and deciding how to route data to it. The old method was to look in a table (called the "host table"), usually stored on a disk of the sending computer. The newer method (called the "Domain Name System") uses the Internet Mail 16 network itself to ask about the names. The Domain Name Sys- tem allows individual institutions to maintain lists of their own names, making them available to all, through the network. The Internet now has so many names that host tables include only a small fraction of them and would be impractically large if they included all. * An Internet computer may have more than one attachment to the Internet. Internet software should try routing mail through one attachment, and if it is not working, should try another if there is one. Some computers on the Internet run software which will give up after trying one. * Many computers on the Internet do not look for designated mail exchangers when they send a message. Another source of differences in the capabilities of computers on the Internet is that the mail transfer agents may be pro- grammed differently. For example: many computers on the Internet support the ".bitnet" qualifier, but not all. Note that if you are sending mail from a computer which suf- fers from one of these restrictions, you can often get the mail delivered by sending it through another computer on the Internet which does not suffer from the same restrictions, using in-care- of addressing. Syracuse University Electronic-Mail Consultant's Guide 17 BITNET MAIL BITNET is a cooperative network of academic institutions. BITNET, NETNORTH, and EARN actually form a single network serving a large part of the world, but some of the administrative tasks are divided three ways. NETNORTH is all the sites in Canada, EARN is all the sites in Europe and the middle east, and BITNET is all the rest though the vast majority are in the United States. The rest of this discussion will refer only to BITNET but applies to all three. BITNET's basic function is to transport files. BITNET also supports "interactive messages" which amount to single lines of text sent from one user to another. The word "message" as used with respect to BITNET often refers to these interactive messag- es, thus you hear BITNET users say the redundant phrase "electronic-mail message" to avoid confusion. The files BITNET transports are in the format of IBM-card input or IBM-lineprinter output. BITNET is actually built out of networking software provided with the VM/CMS operating system which was originally intended to tie together the I/O spooling systems of two or more systems running VM/CMS. BITNET now sup- ports systems other than VM/CMS systems, in particular, VAX/VMS systems (which require the JNET networking software to join BITNET) which now outnumber VM/CMS systems on BITNET. Any BITNET user may send a file to any other BITNET user using a BITNET address. BITNET addresses consist of a username and the name of a computer, but are written in different forms: +---------------------------------------------------------------+ | MMROE AT SUVM | | MMROE@SUVM | | MMROE@SUVM.BITNET | | | | Figure 10: Different forms of a single BITNET address. | +---------------------------------------------------------------+ Different programs require different forms of the address. Each BITNET computer has a BITNET name no longer than 8 characters can do something useful with usernames of no more than 8 characters as that is all BITNET supports. BITNET itself consists of numerous computers tied together with communications links to form a big "tree" shaped network. When you send a file to someone on a computer not directly con- nected to your computer, BITNET first copies the entire file to the first computer on the route from your computer to the desti- BITNET Mail 18 nation. When the file is again intact, it is copied again to the next computer on the route until it reaches the computer used by the recipient. Networks of this sort are known as "store-and- forward" networks. Unlike the Internet, if part of BITNET is down between you and the recipient, the file will go as far along the route as it can, then wait for the next "link" to start func- tioning again, then proceed. An electronic-mail message on BITNET is simply a file sent like any other file. Special commands have been devised to help users compose, send, read, and store files used for mail. Con- ventions have been established to aid in the management of electronic-mail files: they normally have a fileclass of M and a filetype of MAIL and are normally card-image files rather than lineprinter files (BITNET carries along with the file some extra information including a "class" as well as a filename and file- type). By convention, BITNET mail files use the RFC822 format. Unfortunately, the standard VM/CMS command for composing electronic-mail messages, NOTE, does not. BITNET does not enforce the convention so sites are free to make up their own electronic-mail file formats, and some do. This wreaks havoc on the recipients of such messages who may be trying to use electronic-mail programs that can usefully manipulate messages in RFC822 format (e.g. reply to a message, sort it by date or by sender, etc). This ability to exchange files is shared by the large majority of computers on BITNET, but not all. Some implement just enough of this capability to exchange electronic mail, recognizing cer- tain file characteristics (filetype and/or class) to identify the file as mail and ignoring other files. Some may even demand a certain format for the file such as RFC822. Other computers are attached to BITNET through entirely non-standard means and require the services of a mail transfer agent to receive mail. THE COLUMBIA MAILER The Columbia MAILER is one of several mail transfer agents that are in wide use throughout BITNET. Others include PMDF (which may be run on VAX/VMS machines) and IBM's SMTP program. These latter two act as electronic-mail gateways between BITNET and an internet, a function we will discuss later. The Columbia MAILER runs under VM/CMS as a "virtual machine". At Syracuse University, SUVM runs a Columbia MAILER under the name "BITMAIL". To use the Columbia MAILER, programs for composing and sending mail format it in RFC822 format and send it to the nearest Colum- bia MAILER instead of directly to the recipient (on SUVM, EMAIL does this). The Columbia MAILER, in turn, sends it to a mail transfer agent on the same computer as the recipient which deliv- ers it to the recipient. If there is no mail transfer agent on Syracuse University Electronic-Mail Consultant's Guide 19 the receiving computer, then the Columbia MAILER sends the file directly to the recipient. This method has several advantages over the more direct method of sending mail on BITNET: * It sends only a single copy of a message to a computer with two or more recipients if there is a mail transfer agent on the receiving computer to do the final delivery. This saves BITNET network capacity. * It can deliver mail to some BITNET computers which can only receive mail through the services of a mail transfer agent. * It can deliver mail to computers on other electronic-mail networks. * It can handle longer usernames and computer names than BITNET can otherwise handle. * It can use qualifiers to route mail. Sites without Columbia MAILERs can get some or all of these benefits by running a different mail transfer agent (e.g. PMDF) or by offering the user special software to compose messages in the formats required by gateways to transfer mail to other net- works. Examples of the latter are the GMAIL program for VAX/VMS systems and the SENDGATE program for VM/CMS systems. These must be configured in a manner similar to the Columbia MAILER to take the destination address and figure out what gateway should receive the message and what format the gateway expects. SUNRISE offers the GMAIL program with an unusual configuration: it sim- ply sends all mail to BITMAIL, SUVM's Columbia MAILER. This reduces maintenance and assures SUNRISE's users the same reach as SUVM's. QUALIFIERS AND DOMAINS With mail transfer agents that can handle qualifiers, BITNET has a domain scheme similar (on the surface) to Internet domains. We will refer to this as the "BITNET domain scheme". Mail trans- fer agents are configured to check destination addresses with a table of domains, and send all mail destined for certain domains to certain designated mail transfer agents. For example, all BITNET mail directed to computers whose names end with ".SYR.EDU" are directed by other Columbia MAILERs to BITMAIL, SUVM's Colum- bia MAILER. Sites may use this mechanism to make the same set of computer names available to both BITNET and Internet users, but there is the danger that a site could do this inconsistently, e.g. invent some BITNET names that look exactly like Internet names but cannot be reached from the Internet. BITNET Mail 20 REACHING SITES OFF BITNET As was discussed above, mail transfer agents make the sending of mail to non-BITNET sites straightforward. The mail transfer agent identifies Internet addresses and sends such mail to a BITNET/Internet gateway. There are many such gateways: SUVM has one. There are three sites which have volunteered to allow other BITNET sites to use their BITNET/Internet gateways (since not every site has one of their own). These three are the City Uni- versity of New York, Cornell, and Princeton. BITNET sites with- out their own gateways generally configure their mail transfer agents to send all Internet mail to the site closest to them- selves. The BITNET computer-name INTERBIT refers to the computer among these three which is nearest to your own. Mail transfer agents also route through other gateways, reach- ing numerous other electronic-mail networks. Generally, a BITNET domain is defined (i.e., a qualifier is selected) to designate the network and the mail transfer agent is configured to identify such addresses and send the mail to the proper gateway with what- ever additional manipulation is required. WHAT CAN YOUR COMPUTER REACH? Every month, a central BITNET administration redistributes the latest list of names of BITNET computers as well as configuration tables for the Columbia MAILER. Your computer's capabilities depend upon how recently its tables have been updated. Another source of differences is the fact that any BITNET site may connect their computer to non-BITNET computers as if it were on BITNET (i.e., using the same software) if they simply refrain from registering it as a BITNET node. They can send mail to this computer and to their computer it appears to be on BITNET, but other BITNET sites cannot send to it. The biggest factor determining what your computer can reach is whether it runs a Columbia MAILER or one of the alternatives. Computers that do can reach all of BITNET (including computers requiring the services of a mail transfer agent to receive mail) as well as computers on the Internet and numerous other electronic-mail networks. Computers that do not can reach most BITNET computers, but nothing else. Syracuse University Electronic-Mail Consultant's Guide 21 SYSTEMS AT SYRACUSE UNIVERSITY Here are various different kinds of computers found at Syra- cuse University along with descriptions of how you use electronic mail with them. IBM PCS, COMPATIBLES, & MACINTOSHES There is no specific program to use electronic mail from PC's or Macintoshes since they are single user-systems. Only multi- user systems should store received electronic mail because: 1. Mail addressed to computers that are turned off causes problems. The mail waits, using computer storage in the "sending computer" as well as computer and network time to constantly check to see if the receiving computer is up again. Many single-user computers are turned off part of the time. 2. Single-user computers are generally not as secure as multi- user computers. 3. Multi-user computers often have a professional administra- tor who can handle mail-delivery problems. 4. Many users can otherwise use a number of different single- user systems interchangeably. If someone were to send them mail on such a system, they would either be forced to return to it to check their mail. Since people often reply to messages using "return addresses" or "from addresses", sending mail from single-user systems can cause problems. You can use Kermit, Telnet, or TN3270 to reach a multi-user system to which you are allowed access, then use its mail system. There is a program (called POP) which allows you to use internet mail on a multi-user system without using terminal emulation. We have tried it, but do not yet support it. ICARUS Icarus is a "departmental" Unix system owned by CNS which pro- vides no direct services to users, but may be used indirectly. It is on the Internet and is one of the few computers on campus which implement all the features necessary to deliver mail throughout the Internet. This makes it a valuable first target for in-care-of addressing. Systems at Syracuse University 22 PUBLIC WORKSTATION CLUSTER The Public Workstation Cluster is a set of Sun Workstations for general academic use. They are on the Internet and all use the Internet computer name ZOOKEEPER.CNS.SYR.EDU in their electronic-mail addresses. They offer the user the RandMH pack- age of mail commands, using Sendmail to transfer the mail. The cluster's Sendmail recognizes the ".BITNET" qualifier and routes such mail appropriately. It does not use the Internet Domain Name System nor does it look for mail exchangers or alter- nate Internet attachments. RODAN RODAN is a Gould Unix system for general academic use. It is on the Internet and offers the user the RandMH package of mail commands, using the Sendmail program to transfer the mail. RODAN's Sendmail recognizes the ".BITNET" qualifier and routes such mail appropriately. It uses the Internet Domain Name System and looks for alternate Internet connections, but does not look for mail exchangers. SUAIS SUAIS is an IBM MVS system for administrative use. It is on BITNET and offers the user the EMC2 electronic-mail system. SUAIS delivers incoming mail only if the file adheres to EMC2's concept of a mail file, but does not require the use of a mail transfer agent. It can deliver mail only to BITNET comput- ers not requiring the help of a mail transfer agent for delivery. SUMVS SUMVS is an IBM MVS system for general academic use. It is on BITNET and offers (through its APL subsystem) users the MAILMAN electronic-mail system. SUMVS can send electronic mail to all BITNET computers, but requires the use of a mail transfer agent to receive incoming mail. It can exchange mail with other electronic-mail networks. SUMVS is not recommended for use with electronic mail since plans are to discontinue its electronic-mail service. Syracuse University Electronic-Mail Consultant's Guide 23 SUN WORKSTATIONS Many departments have Sun Workstations for their own use. Most of them are on the Internet. Different Sun Workstations on campus are set up to use mail differently. Any can use Telnet (or TN3270 if installed) to reach a multi-user system to handle electronic mail. Some departments have set up mail programs that use storage and return-addresses of multi-user systems to ease the reception of mail. The restrictions upon mail sent from such Sun Workstations varies with the department. SUNRISE SUNRISE is a DEC VAX/VMS system for general academic use. It is on BITNET and the Internet. It offers the standard VAX/VMS command, MAIL, which invokes a program also known as VMSMAIL. VMSMAIL is designed to send mail through a DECnet, but through special addressing, can send mail via the JNET software to BITNET and via the WIN/TCP software to the Internet. A separate user mail program, GMAIL, composes and sends mail to mail-only BITNET nodes and to other networks. A problem associated with systems running JNET is that VMSMAIL's reply command cannot reply to computers off of BITNET. SUNRISE implements a partial solution which solves the problem for replies to Internet computers: VMSMAIL's reply command directs the return message directly through the Internet even if it was received through BITNET. SUNRISE's internet software does not use the Domain Name Sys- tem, look for multiple addresses of Internet sites, or look for mail exchangers. SUNRISE's MAIL command can send to all BITNET computers that do not require the use of a mail transfer agent as well as to the Internet. SUNRISE's GMAIL command can also send mail to the rest of BITNET as well as to other electronic-mail networks. SUVM SUVM is an IBM VM/CMS system for general academic use. It is on BITNET and the Internet. Its command for composing electronic mail, EMAIL, directs mail through SUVM's Columbia MAILER (BITMAIL) and for Internet computers, through SMTP (part of the VM TCP/IP software package). SUVM also has the standard, but limited VM/CMS command to compose mail, NOTE. Reception of mail is handled by the programs RDRLIST and PEEK. SUVM's EMAIL can send to all BITNET computers, and to other electronic-mail networks. It also sends mail to the Internet, Systems at Syracuse University 24 using the Domain Name System, but does not look for mail exchan- gers or alternate Internet attachments of receiving computers. UNIX SYSTEMS Some departments have Unix systems for their own use. Most of these are on the Internet. There are a variety of different sets of mail programs for sending and receiving mail on Unix systems, so the capabilities of the systems vary. VMS SYSTEMS Some departments have DEC VAX/VMS systems for their own use. Most are on a DECnet which interconnects the VMS systems on cam- pus while others run either JNET or WIN/TCP. The capabilities of the systems vary. Syracuse University Electronic-Mail Consultant's Guide 25 THE EASIEST WAY TO REACH NEARLY ANYWHERE Following is a simple procedure which will deliver a message to any of a very large number of computers including virtually all computers on BITNET and the Internet as well as those on many other electronic-mail networks. It is a simpler alternative to the procedure outlined in [5]. 1. Try sending the message in care of SUVM. 2. If this fails, try sending the message from a computer on the Internet in care of ICARUS. This procedure is effective because SUVM has the best BITNET software available for delivering mail can route mail through numerous gateways to numerous other networks. ICARUS has the best Internet software available. The disadvantage is that the mail route is not necessarily the most efficient: the message will be transferred to ICARUS or SUVM before it leaves the campus. The procedure outlined in [5] pro- duces a more straight-forward route. The Easiest Way to Reach Nearly Anywhere 26 GLOSSARY This glossary covers electronic-mail-related networks, pro- grams, and other terms. ACSNET This term has two unrelated meanings. At Syracuse Uni- versity, this term refers to Academic Computing Servi- ces Network, which attaches Academic Computing Servi- ces' computers to many terminals and personal computers throughout the campus as well as connections to the telephone system for use by modems. ACSNET is also the name of the Australian Computer Sciences Network which is the primary network joining educational and research institutions in Australia. ARPANET One of the original national networks that supported electronic mail. It was designed by the Department of Defense to join sites which performed non-classified research for the military. BITMAIL The name of SUVM's "virtual machine" that runs the Columbia MAILER. BITNET A network of over 1000 computers throughout United States and a few other countries. In a technical sense, BITNET, NETNORTH and EARN make up a single net- work so a computer on one can reach computers on any of the three with equal ease. However, they are adminis- tered separately. BITNODE A command on SUVM which, given the BITNET name of a computer, yields a little information about it. BSMTP A modified form of SMPT used on BITNET between mail transfer agents and with gateways. Columbia MAILER A mail transfer agent used by some BITNET computers running the VM operating system (on IBM mainframes). It supports the BITNET domain-name scheme and helps send mail through gateways. SUVM runs the Columbia MAILER under the name BITMAIL. Most other sites use the name MAILER. Crosswell MAILER Another name for the Columbia MAILER. CSNET A network serving computer-science research institu- tions. It actually runs three different types of net- works, an internet (part of the Internet), and X.25 network, and a protocol specifically developed for CSnet that uses dialup connections. The three are con- nected by a central gateway. Syracuse University Electronic-Mail Consultant's Guide 27 DECnet A type of network developed by DEC. Various computers running DEC software at Syracuse University form a DEC- net capable of exchanging electronic mail. The Univer- sity DECnet is shared with NMR Incorporated. DECnet mail is of limited utility because of the small number of machines that use it and there is no general gate- waying capability to exchange mail between a DECnet- only computer and a computer not on DECnet. DNS Abbreviation for Domain Name System. domain An Internet term for the set of Internet names of com- puters that end with a specific set of qualifiers. Domain Name System A distributed database of names of computers maintained by and for the Internet. Each institution enters and maintains the names of their own computers and any com- puter which needs a name uses the Internet to find it. EARN The European Academic Research Network. See BITNET. EMAIL The supported command on SUVM for sending mail. It uses BITMAIL to route mail. EMC2 A mail system which Syracuse University runs as an application on SUAIS. It can send mail to normal BITNET sites, but nowhere else. ESNET A national network which is a component network of the Internet. EZMAIL An experimental mail command on SUVM. Not generally available nor supported. GMAIL A program that runs under the VMS operating system which helps a user send mail through gateways to other networks. It can only send mail, not receive mail. It gives a VMS computer on BITNET approximately the same "reach" as a VM computer that runs the Columbia MAILER. GMAIL on SUNRISE has been configured to send all its mail through BITMAIL on SUVM, giving it exactly BIT- MAIL's reach. HEPNET A national network for computers that do research on high energy physics. It uses DECnet. in-care-of addressing An electronic-mail term for using an address that routes a message first to one computer, then on to another. The most usual way to do this is using a per- cent sign (%). See the section on Internet Mail for more details. Glossary 28 Internet A large internet that serves more than 30,000 computers and includes numerous international, national, region- al, and campus networks. internet A data-communications network built around the TCP/IP family of protocols (as opposed to SNA or Appletalk, etc). JNET A software package which may be installed on a system running the VMS operating system. It gives its system the capability to join BITNET. It is essentially a reimplementation of the function of RSCS. Kermit A file transfer protocol which transfers files between computers through asynchronous communications lines. It is also the name for many programs including PC terminal-emulation programs that implement the Kermit protocol. LISTSERV A program that runs on VM systems, managing mailing lists. SUVM runs it under the name LISTSERV. MAIL Surely a commonly used name for mail commands. VMS's standard mail command is called "MAIL". RiceMAIL's command to send mail is called "MAIL". Mail Exchanger An Internet term for a computer which has been desig- nated to receive mail addressed to another computer. The Internet Domain Name System manages a list of mail exchangers for computers on the Internet. This term is often abbreviated "MX". Mail Transfer Agent A generic name for software that takes a message from the Mail User Agent, figure out where to send it first, store it until it can be sent, send it, and possibly retry if the first time fails. Mail User Agent A generic name for software to help the user read, com- pose, and address messages. MAILBOOK A command which is part of the RiceMAIL package and which allows one to manipulate "NOTEBOOKS", files con- taining copies of messages sent and received. MAILER See Columbia MAILER. Mailman A mail system written in APL used on Syracuse Universi- ty's Sharp APL timesharing system. It can send and receive mail through SUVM's BITMAIL. It is not recom- mended as it will be phased out soon. Syracuse University Electronic-Mail Consultant's Guide 29 MFENET A network which attaches physics departments of various universities that are doing magnetic fusion research to a supercomputer at Lawrence Livermore National Labora- tories. It uses DECnet. MMDF A mail transfer agent used by many Unix systems. It was originally designed for use on CSNET, but is also otherwise used on the Internet. It has roughly the same function as Sendmail. MX Abbreviation for Mail Exchanger. NETNORTH A Canadian network of academic institutions. See BITNET. NOTE The standard VM/CMS command for sending electronic mail. On BITNET, it has been largely replaced by com- mands capable of sending mail off BITNET and to BIT- NET's mail-only computers. See RiceMAIL and EMAIL. NSFnet A collection of internets funded by the NSF to facili- tate research funded by the NSF. All its component networks are part of the Internet. They include BARRN- et, CICnet, JVNCNET, Merit, MIDNET, MRNET, NCSANET, NorthwestNet, NYSERNet, PSCNET, SDSCNET, SESQUINET, SURANET, USAN, and WESTNET. NYSERNet The New York Education and Research Network. A compo- nent network of NSFnet and the Internet. Syracuse Uni- versity's attachment to the rest of the Internet is through NYSERNet. PEEK The VM/CMS command to read incoming electronic-mail. PMDF A mail transfer agent which can be run on VAX/VMS sys- tems. It has roughly the same capabilities as MMDF and Sendmail, but also allows VAX/VMS systems to act as gateways between BITNET or similar networks, internets and DECnets. POP Post Office Protocol. A protocol designed to allow single-user computers to access mail stored on another computer (presumably a multi-user computer) without a "terminal session". The aim is to let the user of the small computer exchange electronic mail without having to learn to use the computer that actually stores the mail. Syracuse University has experimented with POP, but does not provide it as a "supported" service. PROFS An automated office system marketed by IBM which has its own peculiar type of electronic mail. PROFS users of computers on BITNET can exchange electronic mail with other PROFS users of computers on BITNET. PROFS also has some limited capabilities for sending to other sites and importing mail from other sites. Glossary 30 qualifier A part of a name of a computer following a period (.) in the name. For example, the name "ICARUS.CNS.SYR.EDU" has three qualifiers. Qualifiers are used to designate domains of names. RandMH A set of mail commands for Unix systems. RDRLIST A VM/CMS command to aid in the reading of mail. It displays one line about each message waiting to be read. RFC822 A mail protocol that defines the "headers" of mail sent on the Internet. It is also used for many other electronic-mail networks. RiceMAIL A set of mail commands for VM/CMS systems including MAIL and MAILBOOK. RSCS A VM/CMS program which, with the use of synchronous communications hardware and lines, can tie together VM/CMS systems, giving them the ability to transfer files from one to the other. It is the basis for BITNET. Sendmail The standard mail transfer agent provided with Berke- ley's version of Unix. SMTP A mail protocol that defines the "envelope" of mail sent on the Internet. This is usually completely hid- den from the users. SMTP is also the name of a mail transfer agent provided with the IBM's VM TCP/IP soft- ware, which can be used as an electronic-mail gateway between a BITNET-style network and an internet. SPAN The Space Physics Analysis Network. A national network which connects NASA to many research institutions which aid NASA in the analysis of data from space probes. It is built around DECnet. Telnet The internet protocol for managing a users interactive session with a computer on an internet. Also, the usu- al name of the command that provides this service. So to the user, using the "telnet" command on a computer on an internet is much like a terminal emulator and modem on a personal computer. THEnet The Texas Higher Education Network. It uses DECnet. TN3270 A command which uses a variant of the TELNET protocol that, gives the user the full-screen capabilities of an IBM mainframe. USENET A distributed electronic bulletin board offering many of the advantages of electronic mailing lists. Syracuse University Electronic-Mail Consultant's Guide 31 UUCP A Unix program which allows the creation of networks of computers that transfer mail to each other through dial-up modems. A cooperative network of Unix systems has grown through the use of UUCP to tie Unix systems to others. VM Spooling System The mechanism by which files (including electronic-mail messages) are send from one user to another on a com- puter running VM/CMS. Electronic mail to, from, or routed through a VM/CMS system are typically stored in its spooling system. VM TCP/IP A software package which allows a VM/CMS system to be placed on an internet. See also SMTP. VMSMAIL The standard VAX/VMS program for sending and receiving mail. Also known as "MAIL" which is the name of the command that invokes it. WIN/TCP for VMS A software package which allows a VAX/VMS system to be placed on an internet. X.400 The International Standards Organization's official standard protocol for the exchange of electronic mail. It is new and not used much yet, but is expected to replace RFC822 and SMPT eventually. YAMP An experimental mail command on SUVM. Not generally available or supported. Glossary 32 BIBLIOGRAPHY 1. User's Directory of Computer Networks. Austin: University of Texas System, 1988. 2. Crocker, David H. Standard for the Format of ARPA Internet Text Messages. Internet RFC822. 3. Quarterman, John S., and Josia C. Hoskins. "Notable Comput- er Networks." In Communications of the ACM 29:932-971. 4. Webster, Sally. Using Electronic Mail and BITNET Through Academic Computing Services' VM/CMS System. Academic Com- puting Services, Syracuse University, 1988. 5. Wobus, John M. Electronic Mail Network Help Sheet. Comput- ing & Network Services, Syracuse University, 1989. [1] is compiled from data provided by several world-wide net- works about the computers they serve. It includes a "site index", listing the names of the computers by site (i.e., insti- tution). Unfortunately, its data on computers on the Internet is not extensive enough to be very useful. It is supposed to be updated periodically. [3] is an excellent, though slightly dated reference on various electronic-mail networks around the world. [5] is a short companion to this guide, which includes specific methods for sending information from various computers at Syra- cuse University to computers on various national and internation- al networks. Syracuse University Electronic-Mail Consultant's Guide 33 Appendix A ELECTRONIC MAILING LISTS One interesting service provided through electronic mail is electronic mailing lists. Such mailing lists are useful for announcements, and are also useful for maintaining "discussions" through the mail between more than two people, and for allowing a group of people to cooperatively answer questions. A mailing list consists of a list of electronic-mail address- es. Associated with it is an electronic-mail address for the list itself. When you send a message to the list's address, the message is re-sent to all the addresses in the list (This is sometimes known as "exploding" the message and mailing lists have been known as "mail exploders"). This can be done by a person, but it is often done automatically with special software for the purpose. Mailing lists are generally formed to facilitate communica- tions between a particular group of people. Often it is a group of people simply interested in a particular topic. Sites often maintain their own mailing lists for their own purposes, includ- ing only their own people on the list. "National" (or interna- tional) lists may be open to subscription to anyone or may be "private". SUBSCRIBING AND CANCELLING SUBSCRIPTIONS There is no universal way to subscribe to an "open" mailing list. The wrong way is to send a message to the list's address. This results in the message being sent to all members of the list: if it is a large list, then this practice forces lots of people to weed out many such subscription-requests from their incoming mail. The ideal solution is that whoever tells you about the list should also tell you how to subscribe to it. Usu- ally, all you need to know is a second electronic-mail address to which you direct requests to subscribe to the list in question. To cancel your subscription, you send the cancel-request to the same address. On the Internet, there is a convention which allows you to derive the "subscription" address from the "list" address: the computer-name is the same, and the username for subscriptions is the same as the username for the list except that it has the string "-request" appended to the end. For example: Electronic Mailing Lists 34 +---------------------------------------------------------------+ | big-lan@suvm.acs.syr.edu -address of a mailing list. | | big-lan-request@suvm.acs.syr.edu -address to receive requests| | to subscribe to the | | "big-lan" list. | | | | Figure 11: Example of addresses associated with a mailing | | list. | +---------------------------------------------------------------+ A list maintained on BITNET may support the same convention, but it will only be useful for BITNET computers using Columbia MAILERs or the like because of the 8-character limit on normal BITNET usernames. Many BITNET lists are supported by a program called LISTSERV which manages subscriptions for mailing lists automatically. The LISTSERV program itself has a BITNET (electronic-mail) address to which you send requests to subscribe in a very strict format. LISTSERV will take such requests either in an electronic-mail message or as a BITNET "interactive mes- sage". You direct the request to the LISTSERV program on the computer on which the mailing list in question resides. Follow- ing are the commands to subscribe to a list maintained by a LISTSERV and to cancel such a subscription. +---------------------------------------------------------------+ | SUBSCRIBE BIG-LAN Mary Roe | | SIGNOFF BIG-LAN | | | | Figure 12: LISTSERV commands to get on/off a mailing list. | +---------------------------------------------------------------+ To do this through electronic mail, direct the message to the name LISTSERV on the same computer as the mailing list. Follow- ing is the LISTSERV address used to subscribe to BIG-LAN@SUVM: +---------------------------------------------------------------+ | LISTSERV@SUVM | | | | Figure 13: Address of the LISTSERV on SUVM. | +---------------------------------------------------------------+ To do this through "interactive" BITNET commands, use the VM/CMS command "TELL" or the VAX/VMS JNET command "SEND" to send the command. Examples: Syracuse University Electronic-Mail Consultant's Guide 35 +---------------------------------------------------------------+ | CMS: TELL LISTSERV AT SUVM SUBSCRIBE BIG-LAN Mary Roe | | VMS: send listserv@suvm subscribe big-lan Mary Roe | | | | Figure 14: Interactive commands to subscribe to the | | BIG-LAN list. | +---------------------------------------------------------------+ Note that LISTSERV requires that you give it your name. FINDING OUT ABOUT LISTS There is no universal way to find out about lists. Anyone on any electronic-mail network can start one. SRI, the institution which administers the Internet maintains a list of mailing lists along with a brief description of each one and instructions for subscribing. It is available via anonymous FTP from SRI-NIC.ARPA as well as from various BITNET fileservers such as NETSERV. The LISTSERV on BITNIC keeps several mailing lists of broad interest. Also many lists of broad interest are available on numerous LIST- SERVs. To tell what lists a LISTSERV supports send it the com- mand "LIST" (in the same manner as the "SUBSCRIBE" or "SIGNOFF" command except that "LIST" takes no argument). Electronic Mailing Lists 36