Standardizing Network Mail Headers
An interim proposal to give network mail one standard From, Date and Subject header.
Bhushan, A.K., Pogran, K.T., Tomlinson, R.S., and J.E. White, "Standardizing Network Mail Headers", RFC 561, DOI 10.17487/RFC0561, September 1973, <https://www.rfc-editor.org/info/rfc561>.
@misc{rfc561,
series = {Request for Comments},
number = 561,
howpublished = {RFC 561},
publisher = {RFC Editor},
doi = {10.17487/RFC0561},
url = {https://www.rfc-editor.org/info/rfc561},
author = {A.K. Bhushan and K.T. Pogran and R.S. Tomlinson and J.E. White},
title = {{Standardizing Network Mail Headers}},
pagetotal = 3,
year = 1973,
month = sep,
} RFC text
RFC # 561 Abhay Bhushan (AKB) MIT-DMCG
NIC # 18516 Ken Pogran (KP) MIT-MULTICS
Ray Tomlinson (RST) BBN-TENEX
Jim White (JEW) SRI-ARC
5 September 73
Standardizing Network Mail Headers
One of the deficiences of the current FTP mail protocol is that
it makes no provision for the explicit specification of such
header information as author, title, and date. Many systems
send that information, but each in a different format. One
fairly serious result of this lack of standardization is that
it's next to impossible for a system or user program to
intelligently process incoming mail.
Although the long-term solution to the problem is probably to
add commands for specifying such information to the mail
protocol command space (as suggested in RFC 524 -- 17140,), we
hereby propose a more quickly implemented solution for the
interim.
We suggest that the text of network mail, whether transmitted
over the FTP telnet connection (via the MAIL command) or over a
separate data connection (with the MLFL command), be governed by
the syntax below:
Example:
From: White at SRI-ARC
Date: 24 JUL 1973 1527-PDT
Subject: Multi-Site Journal Meeting Announcement
NIC: 17996
At 10 AM Wednesday 25-JULY there will be a meeting
to discuss a Multi-Site Journal in the context of
the Utility. Y'all be here.
Formal Syntax:
<mailtext> ::= <header> <CRLF> <message>
<header> ::= <headeritem> ! <headeritem> <header>
<headeritem> ::= <item> <CRLF>
<item> ::= <authoritem> ! <dateitem> !
<subjectitem> ! <miscitem>
NWG/RFC# 561 AKB KP RST JEW 5-SEP-73 11:19 18516
Standardizing Network Mail Headers RFC 561 / NIC 18516
<authoritem> ::= FROM: <SP> <user> <SP> AT <SP> <host>
<dateitem> ::= DATE: <SP> <date> <SP> <time> - <zone>
<subjectitem> ::= SUBJECT: <SP> <line>
<miscitem> ::= <keyword> : <SP> <line>
<date> ::= <vdate> ! <tdate>
<vdate> ::= <dayofmonth> <SP> <vmonth> <SP> <vyear>
<tdate> ::= <tmonth> / <dayofmonth> / <tyear>
<dayofmonth> ::= one or two decimal digits
<vmonth> ::= JAN ! FEB ! MAR ! APR ! MAY ! JUN !
JUL ! AUG ! SEP ! OCT ! NOV ! DEC
<tmonth> ::= one or two decimal digits
<vyear> ::= four decimal digits
<tyear> ::= two decimal digits
<zone> ::= EST ! EDT ! CST ! CDT ! MST ! MDT !
PST ! PDT ! GMT ! GDT
<time> ::= four decimal digits
<user> ::= <word>
<host> ::= a standard host name
<message> ::= <line> <CRLF> ! <line> <CRLF> <message>
<keyword> ::= <word>
<line> ::= a string containing any of the 128 ASCII
characters except CR and LF
<word> ::= a string containing any of the 128 ASCII
characters except CR, LF, and SP
<CRLF> ::= CR LF
<SP> ::= space
Please note the following:
(1) <authoritem>, <dateitem>, and <subjectitem> may each
appear at most once in <header>; <miscitem> may occur any
number of times. The order of <authoritem>, <dateitem>,
and <subjectitem> is insignificant, but they must proceed
all occurrences of <miscitem>.
(2) The case (upper or lower) of keywords -- specifically,
'FROM', 'DATE', 'SUBJECT' ,'AT', <host>, <zone>, <vmonth>
and <keyword> -- is insignificant. Although 'FROM', for
example, appears in upper-case in the formal syntax above,
in the header of an actual message it may appear as 'From'
(as in the example), or 'from', or 'FrOm', etc.
(3) No attempt has been made to legislate the format of
<user>, except to exclude spaces from it.
(4) The time has no internal punctuation.
(5) No provision is made for multiple authors.
We recommend that mail-sending subsystems which prefix header
information to the text of the user's message be modified
NWG/RFC# 561 AKB KP RST JEW 5-SEP-73 11:19 18516
Standardizing Network Mail Headers RFC 561 / NIC 18516
appropriately, and that other hosts recommend the above
conventions to their users.
ISO Plain Language
On this page
§1The Problem with Mail Headers
The FTP mail protocol makes no provision for explicitly specifying header information such as author, title and date. Many systems send that information, but each in a different format. The authors call the result fairly serious: it is next to impossible for a system or user program to intelligently process incoming mail.
The long-term solution is probably to add commands for such information to the mail protocol command space, as suggested in RFC 524. This RFC proposes a quicker interim answer instead.
Because everyone wrote the sender and date differently, programs could not understand them. One shared layout fixes that.
§2The Proposed Header Syntax
The proposal covers the text of network mail sent either over the FTP Telnet connection with the MAIL command or over a separate data connection with the MLFL command. The mail text is a header, a blank line, then the message.
The header holds a FROM: item, a DATE: item and a SUBJECT: item, each written as a keyword, a colon, a space and a value. Other keyword: items may follow any number of times, which the RFC calls a misc item. The example header begins with From: White at SRI-ARC, a date of 24 JUL 1973 1527-PDT, a subject and a NIC number.
At the top of every message come three lines: who it is from, the date and time, and what it is about. Then a blank line, then the message.
From: White at SRI-ARC
Date: 24 JUL 1973 1527-PDT
Subject: Multi-Site Journal Meeting Announcement
NIC: 17996
At 10 AM Wednesday 25-JULY there will be a meeting
to discuss a Multi-Site Journal in the context of
the Utility. Y'all be here.§3Rules and Recommendations
The author, date and subject items may each appear at most once, in any order, but all of them must come before any misc item. The case of keywords is insignificant, so From, from and FROM all mean the same thing.
The format of the user name is not legislated beyond excluding spaces, the time carries no internal punctuation, and no provision is made for multiple authors. The authors recommend that mail-sending subsystems which prefix header information to a message be modified accordingly, and that other hosts recommend these conventions to their users.
The three main lines can come in any order and capital letters do not matter. Each message has a single author.