Network Working Group
Request for Comments: 785
S. Sluizer
J. Postel
July 1981




This document defines the ISI TOPS20s interface between the Mail Transfer Protocol (MTP) and a mail creation system (e.g., MM, HERMES, etc.) in terms of the files which implement it. The internal structure and name of each file is described below.

For a complete understanding of the MTP protocol as well as the terms used within this document, see RFC 780, "Mail Transfer Protocol".


For each piece of mail, the TOPS20 interface between a mail creation system and MTP is comprised of two files. The first file must be named "^V[--UNSENT-MAIL-CONTROL--^V].MTP.-1", where "^V" represents the character "control V" (ASCII code 026) and the generation number "-1" indicates the next higher generation number (at the time of the file's creation). It is strongly suggested that the second file be named "^V[--UNSENT-MAIL-FILE--^V].MTP.-1", where "^V" and "-1" are as defined before. (However, the actual file name may be chosen by the mail creation system.) Both these files reside in the directory of the user who created the mail (as is currently the case with the MAILER-based system).

"^V[--UNSENT-MAIL-CONTROL--^V].MTP.-1" is the control file. It is an ASCIZ file and contains all information necessary to relay the mail through MTP. It consists of a pointer to the mail text, the source-path, and all destination-paths.

First is "FILE:" followed by the FULL mail text file name (which must include directory name and generation number) followed by <CRLF> (ASCII code 15 followed by ASCII code 12). Note that a structure name is allowed; if not given "PS:" will be assumed. Also note that for each character that must be quoted in a file name the quote character (^V) must be present in the string following "FILE:". Next is "FROM:" followed by the <FROM-path> followed by <CRLF>. Finally, each destination is given in the form "TO:" followed by the <TO-path> followed by <CRLF>. The FROM- and TO-paths include surrounding angle brackets (i.e., <...>) and are identical respectively to the source- and destination-paths described in RFC 780.

July 1981 RFC 785

ISI TOPS20 File Definitions

                       |FILE: <File name> <CRLF>|
                       |FROM: <FROM-path> <CRLF>|
                       |  TO: <TO-path> <CRLF>  |
                       |           ...          |
                       |  TO: <TO-path> <CRLF>  |
        File structure for ^V[--UNSENT-MAIL-CONTROL--^V].MTP.-1
                                Figure 1

"^V[--UNSENT-MAIL-FILE--^V].MTP.-1" is the mail text file. (Note that this is the file to which <File name> in the control file refers.) It is mail which conforms to the standard described in RFC 733, "Standard for the Format of ARPA Network Text Messages".


The older mail creation systems create N copies of a mail text file, one for each of the N addresses in the TO, CC, and BCC fields. Each file is named "^V[--UNSENT-MAIL--^V].<mailbox>^V@<host>.-1", where <mailbox> and <host> are as defined in MTP, and "^V" and "-1" are as defined above.

The interface between the mail creation system and MTP requires only the creation of two files, regardless of the number of addresses in the TO, CC, and BCC fields. The control file contains the source-path and destination-paths information as well as a pointer to the mail text file. The mail text file contains the the RFC 733 header and body.

RFC 785 July 1981

Mail Transfer Protocol


In this example, there were no previously existing versions of either the control file or the mail text file in directory <LINDA> where the message was created. Figure 2 shows the mail text file and figure 3 shows the control file.

      DATE: April 6, 1981
      Sender: Linda at ISIF
      From: Jon Postel <postel@isif>
      To: DCrocker at UDel, Cerf at ISIA
      Cc: postel@ISIF
      Bcc: sluizer@isif
      Subject: MTP discussion

Your comments on the MTP document were most helpful. A revised version will be forthcoming shortly.

Thanks again,

        File contents of <LINDA>^V[--UNSENT-MAIL-FILE--^V].MTP.1
                                Figure 2
          |FROM:<Linda@ISIF><CRLF>                           |
          |TO:<DCrocker@UDel><CRLF>                          |
          |TO:<Cerf@ISIA><CRLF>                              |
          |TO:<postel@ISIF><CRLF>                            |
          |TO:<sluizer@isif><CRLF>                           |
          File contents of ^V[--UNSENT-MAIL-CONTROL--^V].MTP.1
                                Figure 3