Mapping between X.400(1988) / ISO 10021 and RFC 822
RFC 1148

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Network Working Group                                           S. Kille
Request for Comments 1148                      University College London
Updates: RFCs 822, 987, 1026, 1138                            March 1990

          Mapping between X.400(1988) / ISO 10021 and RFC 822

Status of this Memo

   This RFC suggests an electronic mail protocol mapping for the
   Internet community and UK Academic Community, and requests discussion
   and suggestions for improvements.  This memo does not specify an
   Internet standard.  This edition includes material lost in editing.
   Distribution of this memo is unlimited.

   This document describes a set of mappings which will enable
   interworking between systems operating the CCITT X.400 (1988)
   Recommendations on Message Handling Systems / ISO IEC 10021 Message
   Oriented Text Interchange Systems (MOTIS) [CCITT/ISO88a], and systems
   using the RFC 822 mail protocol [Crocker82a] or protocols derived
   from RFC 822.  The approach aims to maximise the services offered
   across the boundary, whilst not requiring unduly complex mappings.
   The mappings should not require any changes to end systems.

   This document is based on RFC 987 and RFC 1026 [Kille86a, Kille87a],
   which define a similar mapping for X.400 (1984).  This document does
   not obsolete the earlier ones, as its domain of application is
   different.

Specification

   This document specifies a mapping between two protocols.  This
   specification should be used when this mapping is performed on the
   Internet or in the UK Academic Community.  This specification may be
   modified in the light of implementation experience, but no
   substantial changes are expected.

                           Table of Contents

   1.  Overview ...............................................    2
   1.1  X.400 .................................................    2
   1.2  RFC 822 ...............................................    3
   1.3  The need for conversion ...............................    4
   1.4  General approach ......................................    4
   1.5  Gatewaying Model ......................................    5
   1.6  RFC 987 ...............................................    7
   1.7  Aspects not covered ...................................    8
   1.8  Subsetting ............................................    9

Kille                                                           [Page 1]
RFC 1148               Mapping X.400(88) and 822              March 1990

   1.9  Document Structure ....................................    9
   1.10  Acknowledgements .....................................   10
   2.  Service Elements .......................................   10
   2.1  The Notion of Service Across a Gateway ................   10
   2.2  RFC 822 ...............................................   11
   2.3  X.400 .................................................   15
   3.   Basic Mappings ........................................   24
   3.1  Notation ..............................................   24
   3.2  ASCII and IA5 .........................................   25
   3.3  Standard Types ........................................   25
   3.4  Encoding ASCII in Printable String ....................   28
   4.  Addressing .............................................   29
   4.1  A textual representation of MTS.ORAddress .............   30
   4.2  Basic Representation ..................................   30
   4.3  EBNF.822-address <-> MTS.ORAddress ....................   34
   4.4  Repeated Mappings .....................................   43
   4.5  Directory Names .......................................   45
   4.6  MTS Mappings ..........................................   45
   4.7  IPMS Mappings ....... .................................   48
   5.  Detailed Mappings ......................................   52
   5.1  RFC 822 -> X.400 ......................................   52
   5.2  Return of Contents ....................................   59
   5.3  X.400 -> RFC 822 ......................................   60
   Appendix A  Differences with RFC 987 .......................   79
   1.  Introduction ...........................................   79
   2.  Service Elements .......................................   80
   3.  Basic Mappings .........................................   80
   4.  Addressing .............................................   80
   5.  Detailed Mappings ......................................   80
   6.  Appendices .............................................   81
   Appendix B  Mappings specific to the JNT Mail ..............   81
   1.  Introduction ...........................................   81
   2.  Domain Ordering ........................................   81
   3.  Acknowledge-To: ........................................   81
   4.  Trace ..................................................   82
   5.  Timezone specification .................................   82