rfc1327.txt

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   The following non-standard services (headers) may be present.  These
   are defined in more detail in Chapter 5 (5.3.4, 5.3.6, 5.3.7):





Hardcastle-Kille                                               [Page 13]

RFC 1327        Mapping between X.400(1988) and RFC 822         May 1992


   Autoforwarded:

   Content-Identifier:

   Conversion:

   Conversion-With-Loss:

   Delivery-Date:

   Discarded-X400-IPMS-Extensions:

   Discarded-X400-MTS-Extensions:

   DL-Expansion-History:

   Deferred-Delivery:

   Expiry-Date:

   Importance:

   Incomplete-Copy:

   Language:

   Latest-Delivery-Time:

   Message-Type:

   Obsoletes:

   Original-Encoded-Information-Types:

   Originator-Return-Address:

   Priority:

   Reply-By:

   Requested-Delivery-Method:

   Sensitivity:

   X400-Content-Type:

   X400-MTS-Identifier:




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   X400-Originator:

   X400-Received:

   X400-Recipients:

2.3.  X.400

2.3.1.  Origination in X.400

   When mapping services from X.400 to RFC 822 which are not supported
   by RFC 822, new RFC 822 headers are defined.  It is intended that
   these fields will be registered, and that co- operating RFC 822
   systems may use them.  Where these new fields are used, and no system
   action is implied, the service can be regarded as being partially
   supported.  Chapter 5 describes how to map X.400 services onto these
   new headers.  Other elements are provided, in part, by the gateway as
   they cannot be provided by RFC 822.

   Some service elements are marked N/A (not applicable).  There are
   five cases, which are marked with different comments:

   N/A (local)
        These elements are only applicable to User Agent / Message
        Transfer Agent interaction and so they cannot apply to RFC
        822 recipients.

   N/A (PDAU)
        These service elements are only applicable where the
        recipient is reached by use of a Physical Delivery Access
        Unit (PDAU), and so do not need to be mapped by the gateway.

   N/A (reception)
        These services  are only applicable for reception.

   N/A (prior)
        If requested, this service must be performed prior to the
        gateway.

   N/A (MS)
        These services are only applicable to Message Store (i.e., a
        local service).

   Finally, some service elements are not supported.  In particular, the
   new security services are not mapped onto RFC 822.  Unless otherwise
   indicated, the behaviour of service elements marked as not supported
   will depend on the criticality marking supplied by the user.  If the
   element is marked as critical for transfer or delivery, a non-



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   delivery notification will be generated.  Otherwise, the service
   request will be ignored.

2.3.1.1.  Basic Interpersonal Messaging Service

   These are the mandatory IPM services as listed in Section 19.8 of
   X.400 / ISO/IEC 10021-1, listed here in the order given. Section 19.8
   has cross references to short definitions of each service.

   Access management
        N/A (local).

   Content Type Indication
        Supported by a new RFC 822 header (Content-Type:).

   Converted Indication
        Supported by a new RFC 822 header (X400-Received:).

   Delivery Time Stamp Indication
        N/A (reception).

   IP Message Identification
        Supported.

   Message Identification
        Supported, by use of a new RFC 822 header
        (X400-MTS-Identifier).  This new header is required, as
        X.400 has two message-ids whereas RFC 822 has only one (see
        previous service).

   Non-delivery Notification
        Not supported, although in general an RFC 822 system will
        return error reports by use of IP messages.  In other
        service elements, this pragmatic result can be treated as
        effective support of this service element.

   Original Encoded Information Types Indication
        Supported as a new RFC 822 header
        (Original-Encoded-Information-Types:).

   Submission Time Stamp Indication
        Supported.

   Typed Body
        Some types supported.  IA5 is fully supported.
        ForwardedIPMessage is supported, with some loss of
        information.  Other types get some measure of support,
        dependent on X.400 facilities for conversion to IA5.  This



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RFC 1327        Mapping between X.400(1988) and RFC 822         May 1992


        will only be done where content conversion is not
        prohibited.

   User Capabilities Registration
        N/A (local).

2.3.1.2.  IPM Service Optional User Facilities

   This section describes support for the optional (user selectable) IPM
   services as listed in Section 19.9 of X.400 / ISO/IEC 10021- 1,
   listed here in the order given.  Section 19.9 has cross references to
   short definitions of each service.

   Additional Physical Rendition
        N/A (PDAU).

   Alternate Recipient Allowed
        Not supported.  There is no RFC 822 service equivalent to
        prohibition of alternate recipient assignment (e.g., an RFC
        822 system may freely send an undeliverable message to a
        local postmaster).  Thus, the gateway cannot prevent
        assignment of alternative recipients on the RFC 822 side.
        This service really means giving the user control as to
        whether or not an alternate recipient is allowed. This
        specification requires transfer of messages to RFC 822
        irrespective of this service request, and so this service is
        not supported.

   Authorising User's Indication
        Supported.

   Auto-forwarded Indication
        Supported as new RFC 822 header (Auto-Forwarded:).

   Basic Physical Rendition
        N/A (PDAU).

   Blind Copy Recipient Indication
        Supported.

   Body Part Encryption Indication
        Supported by use of a new RFC 822 header
        (Original-Encoded-Information-Types:), although in most
        cases it will not be possible to map the body part in
        question.

   Content Confidentiality
        Not supported.



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   Content Integrity
        Not supported.

   Conversion Prohibition
        Supported.  In this case, only messages with IA5 body parts,
        other body parts which contain only IA5, and Forwarded IP
        Messages (subject recursively to the same restrictions),
        will be mapped.

   Conversion Prohibition in Case of Loss of Information
        Supported.

   Counter Collection
        N/A (PDAU).

   Counter Collection with Advice
        N/A (PDAU).

   Cross Referencing Indication
        Supported.

   Deferred Delivery
        N/A (prior).  This service should always be provided by the
        MTS prior to the gateway.  A new RFC 822 header
        Deferred-Delivery:) is provided to transfer information on
        this service to the recipient.

Deferred Delivery Cancellation
      N/A (local).

Delivery Notification
      Supported.  This is performed at the gateway.  Thus, a
      notification is sent by the gateway to the originator.  If
      the 822-MTS protocol is JNT Mail, a notification may also be
      sent by the recipient UA.

Delivery via Bureaufax Service
      N/A (PDAU).

Designation of Recipient by Directory Name
      N/A (local).

Disclosure of Other Recipients
      Supported by use of a new RFC 822 header (X400-Recipients:).
      This is descriptive information for the RFC 822 recipient,
      and is not reverse mappable.





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RFC 1327        Mapping between X.400(1988) and RFC 822         May 1992


DL Expansion History Indication
      Supported by use of a new RFC 822 header
      DL-Expansion-History:).

DL Expansion Prohibited
      Distribution List means MTS supported distribution list, in
      the manner of X.400.  This service does not exist in the RFC
      822 world.  RFC 822 distribution lists should be regarded as
      an informal redistribution mechanism, beyond the scope of
      this control.  Messages will be sent to RFC 822,
      irrespective of whether this service is requested.
      Theoretically therefore, this service is supported, although
      in practice it may appear that it is not supported.

Express Mail Service
      N/A (PDAU).

Expiry Date Indication
      Supported as new RFC 822 header (Expiry-Date:).  In general,
      no automatic action can be expected.

Explicit Conversion
      N/A (prior).

Forwarded IP Message Indication
      Supported, with some loss of information.  The message is
      forwarded in an RFC 822 body, and so can only be interpreted
      visually.

Grade of Delivery Selection
      N/A (PDAU)

Importance Indication
      Supported as new RFC 822 header (Importance:).

Incomplete Copy Indication
      Supported as new RFC 822 header (Incomplete-Copy:).

Language Indication
      Supported as new RFC 822 header (Language:).

Latest Delivery Designation
      Not supported.  A new RFC 822 header (Latest-Delivery-Time:)
      is provided, which may be used by the recipient.

Message Flow Confidentiality
      Not supported.




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RFC 1327        Mapping between X.400(1988) and RFC 822         May 1992


Message Origin Authentication
      N/A (reception).

Message Security Labelling
      Not supported.

Message Sequence Integrity
      Not supported.

Multi-Destination Delivery
      Supported.

Multi-part Body