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RFC 458 UNKNOWN MAIL · FTP

Mail retrieval via FTP

Reading mail through the file transfer protocol without logging in.

On rfc-editor.org ↗
PUBLISHED
February 1973
AUTHORS
R.D. Bressler, R. Thomas
STREAM
Legacy
NEW COMMANDS
RDMF, RDML
SUCCESS CODE FOR NO MAIL
200, text NO MAIL NOW
MAIL TRANSMISSION PATH RDMF
Data connection
MAIL TRANSMISSION PATH RDML
Control connection
DOI
10.17487/RFC0458

RFC text

Original text · RFC Editor View on rfc-editor.org ↗ 
Network Working Group                                        B. Bressler
Request for Comments: 458                                        BBN-NET
NIC: 14378                                                     B. Thomas
                                                               BBN-TENEX
                                                        20 February 1973


                         Mail Retrieval via FTP

   We propose two new FTP commands called ReaDMailFile and ReaDMail.
   These commands are intended to be symmetric with respect to the
   current MLFL and MAIL commands.  They would allow a user to read his
   mail at one or more sites without incurring the overhead of logging
   in and without having to use several different retrieval methods.
   The user might go further and create a program to go around to all
   the server sites and retrieve his mail for him.  The current FTP
   mechanisms provide for password protection, should security be
   required.

   This proposal brings into focus, once again, the problems of
   different users with the same ID, and to a lesser extent, one user
   with multiple IDs.  This RFC does not attempt to address these issues
   at this time, as much effort is currently being devoted to them.
   However, we believe that a satisfactory system for network mail
   should include a mechanism to enable each user to have mail for him
   sent to a single repository (ideally, the site of his choice).  We
   further believe that the two commands proposed here would be useful
   in such an environment as well as within the current network
   environment.

   The format of the commands is

   COMMAND    REPLY
              success        fail

   RDMF       200,250,330    433,450,451,454,455,457,500,507
              secondary replies:
              252            452

   RDML       152,330        433,450,451,455,500,507

   The success reply 200 would take the text "NO MAIL NOW".  For the
   RDMF command the mail itself is transferred over the data connection,
   and the FTP replies come over the TELNET connection.

   For the RDML command both the mail and the FTP replies come over the
   TELNET connection.  The reply 152 is a new code meaning "mail text
   follows" the text that follows may be "NO MAIL NOW".


          [This RFC was put into machine readable form for entry]
     [into the online RFC archives by Helene Morin, Via Genie 12/1999]

AI ELI5

On this page
PROBLEMUsers stored mail at multiple network sites but had to log in to each one to read it.
MECHANISMRFC 458 proposes two new FTP commands, RDMF and RDML, that let users retrieve mail from a remote server without logging in, mirroring the existing MLFL and MAIL commands used for sending.
A PARTIAL SOLUTIONThe proposal enables remote mail access but leaves open the problem of users with multiple network identities.

§1The Mail Reading Problem

Early network users stored mail at one or more remote sites but had no simple way to retrieve it. The File Transfer Protocol (FTP) already had commands to send mail: MLFL (mail file) and MAIL (mail). RFC 458 proposes adding symmetric read commands so users could fetch their mail without logging into the remote system.

The RFC identifies a deeper problem: users with multiple network identities and the same identity claimed by different users. The authors note these issues are not yet solved but believe a solution should include a mechanism for all a user's mail to go to a single repository.

You can send mail to a faraway computer using FTP, but you have to log in to read it. This note says: add commands to read it without logging in.

§2The RDMF and RDML Commands

The proposal defines two commands. RDMF (read mail file) retrieves mail and sends it over the data connection, returning status codes over the control connection. RDML (read mail) returns both mail and replies over the control connection, using a new code 152 to signal that mail text follows.

Both commands handle the case where no mail is waiting by returning the text NO MAIL NOW. Success replies include codes such as 200 or 250. Failures are reported with codes like 433, 450, 451, 454, 455, 457, 500, and 507, with some commands also generating secondary replies.

The two new commands work like the existing mail-sending commands but in reverse: one sends mail on a separate connection, the other sends it mixed with the status messages.

§3Why This Matters

Network mail was distributed across sites. Without read commands, users either had to log in to multiple hosts (requiring credentials at each) or use different mail protocols at different sites. Symmetric read and write commands in FTP would unify the experience. The RFC notes that a user might even write a program to automatically retrieve mail from all their sites.

FTP's existing password protection mechanism would apply to these new commands, providing security where needed.

If you can mail a letter to a faraway place, you should be able to check your mailbox there using the same tool, not have to learn a different method.