RFC 780 (rfc780) - Page 1 of 43
Mail Transfer Protocol
Alternative Format: Original Text Document
MAIL TRANSFER PROTOCOL
Suzanne Sluizer
and
Jonathan B. Postel
RFC 780
May 1981
Information Sciences Institute
University of Southern California
4676 Admiralty Way
Marina del Rey, California 90291
(213) 822-1511
May 1981 RFC 780
Mail Transfer Protocol
TABLE OF CONTENTS
1. INTRODUCTION .................................................. 1
2. THE MTP MODEL ................................................. 2
3. BASIC MAIL .................................................... 4
3.1. Forwarding ............................................... 5
3.2. Source Routing ........................................... 6
4. MULTI-RECIPIENT MAIL .......................................... 8
4.1. Scheme Selection: MRSQ ................................... 8
4.2. Message Text Specification: MAIL ......................... 9
4.3. Recipient Specification: MRCP ........................... 10
4.4. Scheme Mechanics: Recipients First ...................... 10
4.5. Scheme Mechanics: Text First ............................ 12
4.6. Discussion .............................................. 12
5. SPECIFICATIONS ............................................... 16
5.1. MTP Commands ............................................ 16
5.1.1. Command Semantics ..................................... 16
5.1.2. Command Syntax ........................................ 18
5.2. MTP Replies ............................................. 22
5.2.1. Reply Codes by Function Group ......................... 23
5.2.2. Reply Codes in Numeric Order .......................... 24
5.3. Sequencing of Commands and Replies ...................... 25
5.4. State Diagrams .......................................... 28
5.5. Details ................................................. 30
5.5.1. Minimum Implementation ................................ 30
5.5.2. Transparency .......................................... 30
5.5.3. Sizes ................................................. 30
APPENDIX A: TCP ................................................. 32
APPENDIX B: NCP ................................................. 33
APPENDIX C: NITS ................................................ 34
APPENDIX D: X.25 ................................................ 35
APPENDIX E: Theory of Reply Codes ............................... 36
GLOSSARY ......................................................... 39
REFERENCES ....................................................... 42
Network Working Group S. Sluizer
Request for Comments: 780 J. Postel
ISI
Replaces: RFC 772 May 1981
MAIL TRANSFER PROTOCOL
1. INTRODUCTION
The objective of Mail Transfer Protocol (MTP) is to transfer mail
reliably and efficiently.
MTP is designed to be independent of the particular transmission
subsystem and requires only a reliable ordered data stream channel.
Appendices describe the use of MTP with various transport services.
A Glossary provides the definitions of terms as used in this
document.
An important feature of MTP is its capability to relay mail from one
transport environment to another. A transport service provides an
interprocess communication environment (IPCE). An IPCE may cover one
network, several networks, or a subset of a network. A process can
communicate directly with another process anywhere in its own IPCE.
Mail is a special case of interprocess communication. Mail can be
communicated between proceses in different IPCEs by relaying through
a process connected to two (or more) IPCEs. More specifically, mail
can be relayed between hosts on different transport systems by a host
on both transport systems. It is important to realize that transport
systems (or IPCEs) are not one-to-one with networks.
Sluizer & Postel
