RFC 785

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

Here's the title block, bestie: this is RFC 785, "MAIL TRANSFER PROTOCOL: ISI TOPS20 FILE DEFINITIONS" 🎀. It was written by S. Sluizer and J. Postel from ISI in July 1981. It's an informational-style file definitions doc, and it doesn't obsolete or update anything. Let's go! 💖

INTRODUCTION ✨

okay so this doc defines the ISI TOPS20 interface between the Mail Transfer Protocol (MTP) and a mail creation system (think MM, HERMES, etc.) 💅 It does this by spelling out the files that make the interface work. The internal structure and name of each file is described below. 🦋

for the full scoop on MTP and all its terms, you need RFC 780, "Mail Transfer Protocol" 📚

DESCRIPTION 🌸

so for each piece of mail, the TOPS20 interface between a mail creation system and MTP is made of two files 🫶 The first file MUST be named ^V[--UNSENT-MAIL-CONTROL--^V].MTP.-1, where ^V means the character "control V" (ASCII code 026), and the generation number -1 means the next higher generation number (at the time the file is created). It is strongly suggested that the second file be named ^V[--UNSENT-MAIL-FILE--^V].MTP.-1, where ^V and -1 mean the same thing as before. (However, the actual file name may be chosen by the mail creation system.) Both of these files live in the directory of the user who created the mail, which is how it already works with the MAILER-based system. 🏠

^V[--UNSENT-MAIL-CONTROL--^V].MTP.-1 is the control file. It's an ASCIZ file and has all the info needed to relay the mail through MTP. It holds a pointer to the mail text, the source-path, and all the destination-paths. 🗺️

first up is FILE: followed by the FULL mail text file name (which MUST include the directory name and generation number), then <CRLF> (ASCII code 15 followed by ASCII code 12). Note that a structure name is allowed; if one isn't given, PS: will be assumed. Also, 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> and then <CRLF>. Finally, each destination is given as TO: followed by the <TO-path> and then <CRLF>. The FROM- and TO-paths include surrounding angle brackets (<...>), and they're identical to the source-path and destination-paths described in RFC 780, respectively. 💜

+------------------------+
|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. (This is the file that <File name> in the control file points to.) It's mail that conforms to the standard described in RFC 733, "Standard for the Format of ARPA Network Text Messages" 📮

DISCUSSION 💭

the older mail creation systems make 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 mean what they meant above.

the interface between the mail creation system and MTP only needs the creation of two files, no matter how many addresses are in the TO, CC, and BCC fields 🙌 The control file holds the source-path and destination-paths info, plus a pointer to the mail text file. The mail text file contains the the RFC 733 header and body. 🎀

EXAMPLE 🧁

okay so in this example, there were no existing versions of either the control file or the mail text file in directory <LINDA> where the message got 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,
   --jon

File contents of <LINDA>^V[--UNSENT-MAIL-FILE--^V].MTP.1 (Figure 2) 🦋

+--------------------------------------------------+
|FILE:<LINDA>^V[--UNSENT-MAIL-FILE--^V].MTP.1<CRLF>|
+--------------------------------------------------+
|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) 🫧