





Network Working Group                                          E. Thomas
Request for Comments: 1429                    Swedish University Network
                                                           February 1993


                      Listserv Distribute Protocol

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Abstract

   This memo specifies a subset of the distribution protocol used by the
   BITNET LISTSERV to deliver mail messages to large amounts of
   recipients.  This protocol, known as DISTRIBUTE, optimizes the
   distribution by sending a single copy of the message over heavily
   loaded links, insofar as topological information is available to
   guide such decisions, and reduces the average turnaround time for
   large mailing lists to 5-15 minutes on the average. This memo
   describes a simple interface allowing non-BITNET mailing list
   exploders (or other bulk-delivery scripts) to take advantage of this
   service by letting the BITNET distribution network take care of the
   delivery.

Introduction

   Running a mailing list of 1,000 subscribers or more with plain
   "sendmail" while keeping turnaround time to a reasonable level is no
   easy task. Due mostly to its limited bandwidth in the mid-80's,
   BITNET has developed an efficient bulk delivery protocol for its
   mailing lists. Originally introduced in 1986, this protocol was
   refined little by little and now carries 2-6 million mail messages a
   day. In fact, this distribution mechanism implements a general-
   purpose delivery service which can be used by any user of BITNET or
   the Internet. Thus, a simple solution to the "sendmail" turnaround
   problem is to wrap the message and recipient list in a DISTRIBUTE
   envelope and pass it to a BITNET server for delivery.  This may not
   be the best possible solution, but it has the advantage of being easy
   to implement.

   In this document we will use the term "production" to refer to the
   normal operation of the mailing list (or bulk delivery application)
   you want to pipe through the DISTRIBUTE service. That is, the
   "production" options are those you should specify once everything is
   tested and you are confident that the setup is working to your



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   satisfaction. In contrast, "test" and "debug" options can be used to
   experiment with the protocol but should not be used for normal
   operation because of the additional bandwidth and CPU time required
   to generate the various informational reports.

   Finally, it should be noted that the DISTRIBUTE protocol was
   developed to address a number of issues, some of them relevant only
   to BITNET, and has evolved since 1986 while keeping a compatible
   syntax. For the sake of brevity, this RFC describes only a small
   subset of the available options and syntax. This is why the syntax
   may appear unnecessarily complicated or even illogical.

1. Selecting an entry point into the DISTRIBUTE backbone

   The first thing you have to do is to find a suitable site to submit
   your distributions to. For testing, and for testing ONLY, you can
   use:

                         LISTSERV@SEARN.SUNET.SE

   For production use, however, you should select a DISTRIBUTE site in
   your topological vicinity: it would make no sense to pass your
   distributions from California to a server in Sweden if most of your
   recipients are in the US. If your organization is connected to BITNET
   and your BITNET system is part of the DISTRIBUTE backbone, this ought
   to be your best bet. Otherwise you will want to contact someone
   knowledgeable about BITNET (or the author of this RFC if you have no
   BITNET users). Make sure to run through the following checklist
   before sending any production traffic to the site in question:


   a. Do you have good connectivity to the host in question? Does the
      host, in general, have decent BITNET connectivity? There are still
      a few sites that insist on using 9.6k leased lines for BITNET in
      spite of having T1 IP access. You will want to avoid them.

   b. Send mail to the server with "show version" in the message body
      (not in the subject field, which is ignored). Is the server running
      version 1.7f or higher? If so, it should not have given you the
      following warning,

        >>> This server is configured to use PUNCH format for mail <<<

      which means that messages with lines longer than 80 characters
      cannot be handled properly. If the software version is less than
      1.7f, the warning will not be present; instead, check the first
      (bottom) "Received:" field. If it does not say "LMail", do not use
      this server as it probably cannot handle messages with long lines.



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      Finally, make sure that the "Master nodes file" is not older
      than 2 months: there are a handful of sites which never update
      their tables due to staffing problems. They cannot be prevented
      from running LISTSERV, but you will certainly want to avoid them.

   c. How big is your workload? If you are planning to use the service
      for more than 10,000 daily recipients, you should get permission
      from the LISTSERV administrator, both as a matter of courtesy and
      to hear about any restrictions or regularly scheduled downtime they
      might have. For instance, some universities might not allow large
      distributions during prime time, or they may have several
      DISTRIBUTE machines and will want to make sure you use the "right"
      one.  Send mail to "owner-listserv" at the host in question and
      give an estimate of the amount of daily messages and recipients you
      would like to submit. If your message bounces back with "No such
      local user" or the like, it means the server did not pass the above
      test (b) and you don't want to use it anyway.

   An index of sites/hosts which have the required configuration, good
   connectivity, keep their tables up to date and have generally agreed
   to provide this service to anyone in their topological area will be
   published separately in the future.

2. Physical delivery of the DISTRIBUTE request

   The distribution request is delivered via SMTP to the e-mail address
   obtained in step 1 (for instance, LISTSERV@SEARN.SUNET.SE). In fact,
   as long as you can somehow get mail to the server's host, you can use
   the service; SMTP is just the most convenient way of doing so.

2.1. Contents of MAIL FROM: field

   You should set the MAIL FROM: field to the address of the person who
   maintains your mailing list or, generally speaking, to the address of
   a human being who can take action in case the message fails to reach
   the DISTRIBUTE server's host. This is a very rare occurrence.

2.2. Contents of RCPT TO: field

   The RCPT TO: field points to the server's address (for instance,
   LISTSERV@SEARN.SUNET.SE).

2.3. Contents of the RFC822 header

   After the DATA instruction, you must supply a valid RFC822 header
   with a "From:" field pointing to the mailbox that should receive
   notification of delivery problems, bounced mail, and so on. This can
   be the same as the MAIL FROM: field, an address of the type "owner-



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   xxxx@yourhost", etc.  DO NOT PUT THE LIST SUBMISSION ADDRESS THERE,
   or you will get mailing loops.

   For testing, the "From:" field should point to your own mailbox, so
   that you get the responses from the server.

   As long as RFC822 syntax is respected, the only field that matters is
   the "From:" field (or "Sender:", "Resent-From:", etc.). In practice
   this means you can just pipe the distribution request into "mail
   listserv@whatever" and let your mail program build all the headers.

3. Format of the DISTRIBUTE request

   The body of the message delivered to LISTSERV defines the recipients
   of the distribution and the text (header + body) of the RFC822
   message you want to have delivered. The request starts with a "job
   card", followed by a DISTRIBUTE command, a list of recipients, and
   finally the message header and body.

3.1. Syntax of the JOB card

   The purpose of the JOB card is to make sure that any spurious text
   inserted by mail gateways or the like is flushed and not erroneously
   interpreted as a command. It can optionally be used to associate a
   "job name" with the request, in case you want to use tools to assist
   you in processing the notifications you get from the DISTRIBUTE
   servers when running in test mode. The syntax is as follows:

   //jobname JOB ECHO=NO

   "jobname" can be anything as long as it does not contain blanks, and
   can be omitted. LISTSERV generally ignores case when parsing
   commands, so you can use "job" or "Job" if you prefer. The ECHO=NO
   keyword is required for production use, to suppress the "resource
   usage summary" you would otherwise get upon completion of your
   delivery. You may want to omit it when testing.

3.2. Syntax of the DISTRIBUTE command

   Below the JOB card, you must supply the following line:

   DISTRIBUTE MAIL

   For production mode, do not specify anything else on that line. When
   testing, you should add ACK=MAIL in order to get an acknowledgement
   confirming the delivery. There are two other useful options:
   DEBUG=YES, which instructs the server to produce a report showing how
   the various recipients will be routed, but without actually



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   delivering the message; and TRACE=YES, which does the same but does
   deliver the message. Before making a "live" test with your actual
   recipients list, you should tack the DEBUG=YES option once to make
   sure you got all the parameters and syntax right, and get a rough
   idea of the efficiency of the distribution (see the section on
   performance).

3.3. Giving the list of recipients

   The list of recipients follows the DISTRIBUTE line and is specified
   as follows:

   //To DD *
   user1@host1 BSMTP
   user2@host2 BSMTP
   /*

   The two lines starting with a "/" have to be copied as-is. Each of
   the lines in between contains the address of one of the recipients,
   followed by a blank and by the word "BSMTP", which indicates that you
   do not want the header rewritten. There are four restrictions:

   a. The address must be a plain "local-part@hostname" - no name string,
      no angle bracket, no source route, etc. Bear in mind that the
      DISTRIBUTE server is not in the same domain as you: all the
      addresses should be fully qualified.

   b. If the local-part is quoted, it must be quoted from the first word
      on.  Technically, RFC822 allows: Joe."Now@Home".Smith@xyz.edu, but
      for performance reasons this form is not supported. Just quote the
      first word to tell LISTSERV to run the address through the full
      parser: you would write "Joe"."Now@Home".Smith@xyz.edu instead.

   c. The local-part of the address may not start with an (unquoted)
      asterisk.  You can bypass this restriction by quoting the local
      part and using a %-hack through the server's host:
      "***JACK***%jack-ws.xyz.edu"@server-host.

   d. Blanks are not allowed anywhere in the address.

   You can use the pseudo-domain ".BITNET" for BITNET recipients: it is
   always supported within DISTRIBUTE requests.

3.4. Specifying the message text

   After the last recipient and the closing "/*", add the following
   line,




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   //Data DD *,EOF

   followed by the RFC822 message (header + body) that you want
   delivered.  The EOF option indicates that the message header and body
   will extend until the end of the message you are sending to the
   DISTRIBUTE server.  If you are worried about extraneous data being
   appended by a gateway, remove the EOF option, add a closing "/*" line
   after the end of the message, followed by a "// EOJ" card to flush
   any remaining text. This, however, will fail if the message itself
   contains a "/*" line; you would have to insert a space before any
   such line.

4. Examples

   Here is an (intentionally short) example to clarify the syntax:

   ----- cut here -----
   //Test JOB
   Distribute mail Ack=mail Debug=yes
   //To DD *
   joe@ws-4.xyz.edu BSMTP
   jack@abc.com BSMTP
   jim@tamvm1.bitnet BSMTP
   jill@alpha.cc.buffalo.edu BSMTP
   james@library.rice.edu BSMTP
   /*
   //Data DD *,EOF
   Date:         Tue, 19 Jan 1993 10:57:29 -0500
   From:         Robert H. Smith <RHS@eta.abc.com>
   Subject:      Re: Problem with V5.41
   To:           somelist@some.host.edu

   I agree with Jack, V5.41 is not a stable release. I had to fall back
   to V5.40 within 5 minutes of installation...

                                           Bob Smith
   ----- cut here -----

   Note: some of the hostnames are genuine, but the usernames are all
   fictitious.

   You would get the following reply:

   --------------------------------------------------------------------
   Job "Test" started on 20 Feb 1993 01:09:40

   > Distribute mail ack=mail debug=yes
   Debug trace information:



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   ABC.COM                   goes to SEARN    (213) - single recipient
   ALPHA.CC.BUFFALO.EDU      goes to UBVM     (027) - single recipient
   LIBRARY.RICE.EDU          goes to RICEVM1  (022) - single recipient
   TAMVM1                    goes to TAIVM1   (247) - single recipient
   WS-4.XYZ.EDU              goes to SEARN    (213) - single recipient

   Path information:

    TAIVM1  : UGA      RICEVM1  TAIVM1
    UBVM    : UGA      UBVM
    RICEVM1 : UGA      RICEVM1

   (Debug) Mail forwarded to LISTSERV@UGA      for   3 recipients.
   (Debug) Mail posted via BSMTP to jack@ABC.COM.
   (Debug) Mail posted via BSMTP to joe@WS-4.XYZ.EDU.

   Job "Test" ended   on 20 Feb 1993 01:09:40

   Summary of resource utilization
   -------------------------------
    CPU time:        0.086 sec                Device I/O:     6
    Overhead CPU:    0.045 sec                Paging I/O:     5
    CPU model:        9221                    DASD model:  3380
   --------------------------------------------------------------------

   To actually perform the distribution and get an acknowledgement, you
   would change the first two lines as follows:

   ----- cut here -----
   //Test JOB Echo=NO
   Distribute mail Ack=mail
   --------------------

   And you would get the following reply:

   --------------------------------------------------------------------
   Mail forwarded to LISTSERV@UGA      for   3 recipients.
   Mail posted via BSMTP to jack@ABC.COM.
   Mail posted via BSMTP to joe@WS-4.XYZ.EDU.
   --------------------------------------------------------------------

   Finally, by removing the "Ack=mail" keyword you would perform a
   "silent" distribution without any acknowledgement, suitable for
   production mode.







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RFC 1429              Listserv Distribute Protocol         February 1993


5. Performance

   The efficiency of the distribution depends mostly on the quality and
   accuracy of the topological information available to the DISTRIBUTE
   server (and, in some extreme cases, on system load). For BITNET
   recipients, the typical turnaround time for reasonably well connected
   systems is 5-15 minutes. Internet recipients fall in two categories:
   those which can be routed to a machine within or close to the
   recipient's organization (average turnaround time 5-20 minutes), and
   those for which no topological information is available at all. In
   that case the delivery can take much longer, but usually remains
   faster than with a vanilla sendmail setup. At the time being,
   topological information is available for most top-level domains
   outside the US and for many sub-domains of EDU and GOV.

   You can measure the efficiency of the distribution using the
   DEBUG=YES option as explained above. Recipients which get forwarded
   to another server usually get delivered within 5-20 minutes (except
   to poorly connected sites or countries, for which not much can be
   done). Recipients which are handled locally are passed to a local
   SMTP agent whose efficiency depends very much on the amount of
   "burst" queries the local name server can handle in quick succession.

   A number of projects are currently underway to investigate the
   feasibility of improving the quality of the topological information
   available to the DISTRIBUTE servers for the Internet.

Security Considerations

   Security issues are not discussed in this memo.

Author's Address

   Eric Thomas
   Swedish University Network
   Dr.Kristinas vaeg 37B
   100 44 Stockholm, Sweden

   E-mail: ERIC@SEARN.SUNET.SE












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