Mail Box Protocol: Version 2

Network Working Group                                          R. Watson
Request for Comments: 221                                        SRI-ARC
NIC: 7612                                                 25 August 1971


                     A Mail Box Protocol, Version-2

INTRODUCTION

   Initial reaction to RFC 196, "A Mail Box Protocol", NIC (7141,)
   indicates general agreement on the need for such a mechanism.  The
   conventions suggested in RFC 196 assumed only the use of the Data
   Transfer Protocol (in NIC 7104) in order to simplify an initial
   implementation.  The valid argument, we believe, has been made that
   sites will also implement the File Transfer Protocol and that as much
   as possible the Mail Box Protocol should be a subset of it.  This
   version is in answer to this suggestion.

   The purpose of a mail box protocol is to provide at each site a
   standard mechanism to receive sequential files for immediate or
   deferred printing or other uses.  The files for deferred printing
   would probably be stored in intermediate disk files, although details
   of how a file is handled, stored, manipulated, or printed at a site
   are not the concern of this protocol.

   A mail box, as we see it, is simply a write only (from the Network)
   sequential file to which messages and documents are appended,
   separated by an appropriate site dependent code.

   It is also assumed that there would be a program at the sending site
   which sends the file in the format given below with the optional
   control codes when appropriate.  This program could probably be
   accessed as a subcommand of the Telnet program.

   The motivation for developing this protocol is the Network
   Information Center's (NIC) need to be able to deliver messages and
   documents to remote sites, and to be able to receive documents for
   cataloging, redistribution, and other purposes from remote sites
   without having to know the details of path name conventions and file
   system commands at each site.  Multiple mail boxes (256) are allowed
   at each site and are identified as described below.  The default is
   mail box number 0 for use with the standard mail printer defined
   below.

   The only place where the Mail Box Protocol has a potential conflict
   with the File Transfer Protocol is in file naming conventions.  The
   File Transfer Protocol assumes that the using site will use a
   filename which follows the access and file path name conventions of
   the serving site and that this information would be supplied by the
   user.  In the Mail Box protocol we would like not to have to
   explicitly know the path name conventions at each site.

   In other words there is a need for a network virtual pathname
   convention.  We did not want to solve this problem in general at this
   time and in RFC 196, NIC 7141, proposed the use of a separate socket
   for mail type delivery and the use of an integer 0-127 to specify the
   address of a specific file (Mail Box) to be appended to as the
   simplest form of network-wide standard file name convention for an
   initial implementation.

   To follow more closely the spirit of the File Transfer Protocol, I
   would now recommend the Append Request be specifically used and that
   the standard socket agreed on for use with the File Transfer Protocol
   also be used.  Following the byte indicating an Append request, there
   would be a standard agreed-upon string of letters followed by a
   number, indicating that this is a mail box append request.  A
   suggested name string would be NETMAIL#, where # is a byte
   interpreted as a mail box number 0-255.  If the above suggested Mail
   Box file naming convention is unsuitable and some other network-wide
   standard mail box naming can be agreed on, then it can be used.
   Please let me know how you feel about this naming convention.

   Given agreement on a standard mail box pathname, then the Mail Box
   Protocol can utilize a subset of the File Transfer Protocol
   conventions to be given below.

   The other problem which was raised about the Mail Box Protocol was
   the possibility of someone accidentally or deliberately flooding the
   printer of a site with garbage, as there are no access or file size
   controls.  Some thinking and discussions of this problem have yielded
   no simple satisfactory solutions.  I would recommend initial
   implementations without standard special safeguards in this area.
   Safeguards would be a site-dependent option.  Standard safeguards for
   the above problem can be easily added later if they really prove
   necessary and satisfactory ones can be agreed on.

                       MAIL BOX PROTOCOL - VERSION 2

   The Mail Box Protocol will use established network conventions,
   specifically the Network Control Program, Initial Connection
   Protocol, Data Transfer Protocol, and File Transfer Protocol (as
   described in Current Network Protocols, NIC 7104).

   The normal transmission for Mail Box 0 is to be Network ASCII.  The
   standard receiving mail printer for mail box number 0 is assumed to
   have a print line 72 characters wide, and a page of 66 lines.  The
   new line convention will be carriage return (Hex '0D'), (Octal '015')
   followed by line feed (Hex '0A') (Octal '012') as per the Telnet
   Protocol, RFC 158, NIC 6768.  The standard printer will accept form
   feed (Hex '0C') (Octal '014') as meaning move paper to the top of a
   new page.

   It is the sender's responsibility to control the length of the print
   line and page.  If more than 72 characters per line are sent, or if
   more than 66 lines are sent without a form feed, then the receiving
   site can handle these situations as appropriate for them.  These
   conventions can be changed by control codes as described below.

   At the head of the message or document sent to mail box number 0
   there is to be an initial address string terminated by a form feed.
   This address string is to contain the sender's name and address, and
   the receiver's name and address formatted in some reasonable, easy-
   to-read form for a clerk to read and distribute.  Comments could also
   be included in the address string.

   The format of information in mail boxes other than mail box number 0
   is not explicitly defined by this protocol.

Initial Connection

   Initial Connection will be as per the Official Initial Connection
   Protocol, Document #2, NIC 7101, to the standard File Transfer socket
   not yet assigned.  A candidate socket number, socket #3, has been
   suggested.

File Transfer

   The mail item (file) to be transferred would be transferred according
   to the File Transfer Protocol.

   As per the File Transfer Protocol, a file (mail item) can be sent in
   more than one data transaction as defined in the Data Transfer
   Protocol.  End of file is indicated by the file separator (as defined
   in Data Transfer Protocol) or by closing the connection.

Order of Transactions

   The only basic operation required is an append.

                    Append Request

   (Mailer) User  -------------------->  server (Mail Box)

                     <File - data>

                   ------------------->

                   End of File indication

                   ------------------->

                       Acknowledge

                   <-------------------

   The data type default is network ASCII.  The standard line printer
   default is as defined above.  Other control transactions can be used.

CONTROL TRANSACTIONS TO BE USED

   OP CODE

   Hex     Octal
   00      000     Change data type identifier
   09      011     Error or unsuccessful terminate
   0A      012     Acknowledge or successful terminate
   0B      013     Append request (add to existing file)
   5A      132     Change printer control settings

DATA TYPE CODES

   All data types of the File Transfer Protocol can be used for special
   applications.  For Mail Box 0, default is 8 bit bytes of Network
   ASCII characters.

ERROR CODES

   All error codes defined in the File Transfer Protocol could be
   returned.

PRINTER CONTROL CODES

     Hex     Octal
     01      321     Meaning:  Set line width to 72 characters
     02      322     Meaning:  Use the full width of your printer
     03      323     Meaning:  Set page size to 66 lines
     04      324     Meaning:  Set page size to infinite

   Other virtual printer control codes can be added in the future.
   Other classes of control codes can be added as the need arises.

   <JOURNAL>7612.NLS;1, 27-AUG-71 10:41 RWW ; (Expedite) Title:
   Author(s): Richard W. Watson/RWW; Distribution: SDC2 TFL JWM JFH REL
   AOJO JEW AWH DLM PWF RAW HRVZ AAM RLS JMM JMW AKB PMK TNP ASL BMW JAM
   EAF RTB JMP BDW JTM JCL AJB CDS RFH EMA;/NWG; Sub-Collections: NWG
   ARC NIC; RFC# 221; Clerk: RWW;
   Origin: <WATSON>MAIL.NLS;4, 27-AUG-71 9:51 RWW ;


         [ This RFC was put into machine readable form for entry ]
            [ into the online RFC archives by Ryan Kato 6/01 ]