RFC 759 (rfc759) - Page 1 of 71
Internet Message Protocol
Alternative Format: Original Text Document
IEN: 113
RFC: 759
INTERNET MESSAGE PROTOCOL
Jonathan B. Postel
August 1980
Information Sciences Institute
University of Southern California
4676 Admiralty Way
Marina del Rey, California 90291
(213) 822-1511
August 1980
Internet Message Protocol
TABLE OF CONTENTS
PREFACE ........................................................ iii
1. INTRODUCTION ..................................................... 1
1.1. Motivation ................................................... 1
1.2. Scope ........................................................ 1
1.3. The Internetwork Environment ................................. 2
1.4. Model of Operation ........................................... 2
1.5. Interfaces ................................................... 4
2. FUNCTIONAL DESCRIPTION ........................................... 5
2.1. Terminology .................................................. 5
2.2. Assumptions ................................................. 5
2.3. General Specification ........................................ 6
2.4. Mechanisms ................................................... 7
2.5. Relation to Other Protocols ................................. 10
3. DETAILED SPECIFICATION .......................................... 13
3.1. Overview of Message Structure ............................... 13
3.2. Message Structure ........................................... 14
3.3. Identification .............................................. 15
3.4. Command ..................................................... 15
3.5. Document .................................................... 19
3.6. Message Objects ............................................. 20
3.7. Data Elements ............................................... 27
4. OTHER ISSUES .................................................... 35
4.1. Accounting and Billing ...................................... 35
4.2. Addressing and Routing ...................................... 36
4.3. Encryption .................................................. 37
5. The MPM: A Possible Architecture ............................... 39
5.1. Interfaces .................................................. 39
5.2. MPM Organization ............................................ 40
6. EXAMPLES & SCENARIOS ............................................ 45
Example 1: Message Format ........................................ 45
Example 2: Delivery and Acknowledgment ........................... 47
Postel [Page i]
August 1980
Internet Message Protocol
Table Of Contents
7. SPECIFICATION SUMMARY ........................................... 55
7.1. Message Fields .............................................. 55
7.2. Deliver Message ............................................. 58
7.3. Acknowledge Message ......................................... 59
7.4. Probe Message ............................................... 61
7.5. Response Message ............................................ 62
7.6. Cancel Message .............................................. 64
7.7. Canceled Message ............................................ 66
7.8. Data Element Summary ........................................ 68
REFERENCES .......................................................... 69
[Page ii] Postel
August 1980
Internet Message Protocol
PREFACE
This is the second edition of this specification and should be treated
as a request for comments, advice, and suggestions. A great deal of
prior work has been done on computer aided message systems and some of
this is listed in the reference section. This specification was shaped
by many discussions with members of the ARPA research community, and
others interested in the development of computer aided message systems.
This document was prepared as part of the ARPA sponsored Internetwork
Concepts Research Project at ISI, with the assistance of Greg Finn,
Suzanne Sluizer, Alan Katz, Paul Mockapetris, and Linda Sato.
Jon Postel
Postel [Page iii]
IEN: 113 J. Postel
RFC: 759 USC-ISI
August 1980
INTERNET MESSAGE PROTOCOL
1. INTRODUCTION
This document describes an internetwork message system. The system is
designed to transmit messages between message processing modules
according to formats and procedures specified in this document. The
message processing modules are processes in host computers. Message
processing modules are located in different networks and together
constitute an internetwork message delivery system.
This document is intended to provide all the information necessary to
implement a compatible cooperating module of this internetwork message
delivery system.
1.1. Motivation
As computer supported message processing activities grow on individual
host computers and in networks of computers, there is a natural desire
to provide for the interconnection and interworking of such systems.
This specification describes the formats and procedures of a general
purpose internetwork message system, which can be used as a standard
for the interconnection of individual message systems, or as a message
delivery system in its own right.
This system also provides for the communication of data items beyond
the scope of contemporary message systems. Messages can include data
objects which could represent drawings, or facsimile images, or
digitized speech. One can imagine message stations equipped with
speakers and microphones (or telephone hand sets) where the body of a
message or a portion of it is recorded digitized speech. The output
terminal could include a graphics display, and the message might
present a drawing on the display, and verbally (via the speaker)
describe certain features of the drawing. This specification provides
for the composition of complex data objects and their encoding in
machine independent basic data elements.
1.2. Scope
The Internet Message Protocol is intended to be used for the
transmission of messages between networks. It may also be used for
the local message system of a network or host. This specification was
Postel
