





Network Working Group                                       C. Allocchio
Request for Comments: 1405                              I.N.F.N. - Italy
                                                            January 1993


       Mapping between X.400(1984/1988) and Mail-11 (DECnet mail)

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  Discussion and suggestions for improvement are requested.
   Please refer to the current edition of the "IAB Official Protocol
   Standards" for the standardization state and status of this protocol.
   Distribution of this memo is unlimited.

Abstract

   This document describes a set of mappings which will enable inter
   working between systems operating the CCITT X.400 ( 1984 / 1988 )
   Recommendations on Message Handling Systems, and systems running the
   Mail-11 (also known as DECnet mail) protocol. The specifications are
   valid within DECnet Phase IV addressing and routing scheme.

   The complete scenario of X.400 / RFC822 / Mail-11 is also considered,
   in order to cover the possible complex cases arising in multiple
   gateway translations.

   This document covers mainly the O/R address to DECnet from/to address
   mapping (and vice versa); other mappings are based on RFC 1327 and
   its eventual future updates.

   This is a combined effort of COSINE S2.2, the RARE MSG Working Group,
   and the IETF X.400 Ops Working Group.

Chapter 1 - Introduction

1.1. X.400

   The standard referred shortly into this document as "X.400" relates
   to the CCITT 1984 and 1988 X.400 Series Recommendations covering the
   Message Oriented Text Interchange Service (MOTIS). This document
   covers the Inter Personal Messaging System (IPMS) only.

1.2. Mail-11

   Mail-11, also known as DECnet mail and often improperly referred as
   VMSmail, is the proprietary protocol implemented by Digital Equipment
   Corporation (DEC) to establish a real-time text messaging system



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   among systems implementing the DECnet Phase IV networking protocols.

1.3. RFC822

   RFC822 was defined as a standard for personal messaging systems
   within the DARPA Internet and is now diffused on top of many
   different message transfer protocols, like SMTP, UUCP, BITNET, JNT
   Grey Book, CSnet. Its mapping with X.400 is fully described in
   RFC1327. In this document we will try to consider its relations with
   Mail-11, too.

1.4. The user community

   The community using X.400 messaging system is currently growing in
   the whole world, but there is still a number of very large
   communities using Mail-11 based messaging systems willing to
   communicate easily with X.400 based Message Handling Systems. Among
   these large DECnet based networks we can include the High Energy
   Physics network (HEPnet) and the Space Physics Analysis Network
   (SPAN).

   These DECnet communities will in the future possibly migrate to
   DECnet Phase V (DECnet-OSI) protocols, converting thus their
   messaging systems to OSI specifications, i.e., merging into the X.400
   MHS; however the transition period could be long, and there could
   always be some DECnet Phase IV communities around.

   For these reasons a set of mapping rules covering conversion between
   Mail-11 and X.400 is described in this document.

   This document also covers the case of Mail-11 systems implementing
   the "foreign mail protocol" allowing Mail-11 to interface other mail
   systems, including RFC822 based system.

Chapter 2 - Message Elements

2.1. Service Elements

   Mail-11 protocol offers a very restricted set of elements composing a
   Inter Personal Message (IPM), whereas X.400 specifications support a
   complex and large amount of service elements. Considering the case
   where a message is relayed between two X.400 MHS via a DECnet network
   this could result in a nearly complete loss of information. To
   minimise this inconvenience most of X.400 service elements will be
   mapped into Mail-11 text body parts. To consider also the case when a
   message originates from a network implementing RFC822 protocols and
   is relayed via Mail-11 to and X.400 MHS, the applied mapping from
   X.400 service elements into Mail-11 text body part the rules



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   specified in RFC1327 and their updates will be used, producing an
   RFC822-like header.

2.2. Mail-11 service elements

   All envelope (P1) and header (P2) Mail-11 service elements are
   supported in the conversion to X.400. Note that Mail-11 P1 is solely
   composed by P1.From and P1.To, and any other Mail-11 element belongs
   to Mail-11 P2:

        - P1.From
                maps to P1.Originator

        - P1.To
                maps to P1.Primary Recipient

        - P2.From
                maps to P2.Originator

        - P2.To
                maps to P2.Primary Recipient

        - Cc
                maps to P2.Copy Recipient

        - Date
                maps to Submission Time Stamp

        - Subj
                maps to Subject

   Any eventual RFC822-like text header in Mail-11 body part will be
   interpreted as specified into RFC1327 and its updates.

2.3. X.400 service elements

   The following X.400 service elements are supported directly into
   Mail-11 conversion:

        - P1.Originator
                maps to P1.'From'

        - P1.Primary Recipients
                maps to P1.'To'

        - P2.Originator
                maps to P2.'From'




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        - P2.Primary Recipients
                maps to P2.'To'

        - Copy Recipients
                maps to 'Cc'

        - Submission Time Stamp
                maps to 'date'

        - Subject
                maps to 'Subj'

   The following X.400 service element is partially supported into
   Mail-11 conversion:

        - Blind Copy Recipient
                to ensure the required privacy, when a message contains
                a BCC address, the following actions occurs:
                - a new message is created, containing the body parts;
                - a new envelope is added to the new message, containing
                  the originator and the BCC recipient addresses only;
                - a note is added to the message informing the BCC
                  recipient about the fact that the message was a BCC;
                - the new message is delivered separately;
                - a note is added to the message delivered to TO and CC
                  recipients informing them about the fact that there
                  were some BCC recipients, too.

   Any other X.400 service element support is done accordingly to
   RFC1327 including the mapped element into the RFC822-like header into
   Mail-11 body part.

Chapter 3 - Basic Mappings

   The basic mappings indicated in RFC1327 and its updates should be
   fully used.

Chapter 4 - Addressing

4.1. Mail-11 addressing

   Mail-11 addressing can vary from a very simple case up to complex
   ones, if there are other Mail-11 to "something-else" gateways
   involved. In any case a Mail-11 address is an ASCII string composed
   of different elements.






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4.2. X.400 addressing

   On the other hand, An X.400 O/R address is a collection of
   attributes, which can anyway be presented as an IA5 textual
   representation as defined in chapter 4 of RFC1327.

4.3. Mail-11 address components

   Let us start defining the different parts composing a Mail-11
   address. We can consider any Mail-11 address as composed by 3 parts:

        [[route]::] [[node]::] local-part

   where 'route' and 'node' are optional and only 'local-part' is
   compulsory.

   Here comes a strict definition of these elements

     node = *(ALPHA/DIGIT) / *DIGIT / *DIGIT "." *DIGIT

     route = *(node "::")

     local-part = username / nickname / for-protocol

     username = *(ALPHA/DIGIT)

     nickname = <printablestring - <" " and HTAB>>

     for-protocol = (f-pref f-sep <">f-address<">)

     f-pref = *(ALPHA/DIGIT)

     f-sep = "%" / "::"

     f-address = printablestring / RFC822-address / X400-text-address

     X400-text-address = <textual representation of an X.400 O/R addr>

   Please note that in x-text-address both the ";" notation and the "/"
   notation are equivalent and allowed (see examples in different sect.)











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   Some examples:

      route           node    local-part
      -----------------------------------------------------------
                              USER47
                      MYNODE::BETTY
      BOSTON::CLUS02::GOOFY1::MARY34
                              IN%"M.P.Tracy@Dicdum.cc.edu"
              UCLA13::MVAX93::MRGATE::"MBOX1::MBX34::MYC3::BOB"
                      MIAMI2::George.Rosenthal
              CCUBVX::VS3100::Jnet%"IAB3425@IBAX23L"
                              MRGATE::"C=xx::A=bbb::P=ppp::S=Joe"
                      MAINVX::IN%"path1!path2!user%dom"
                      GWX400::gw%"C=xx;ADMD=aaa;PRMD=ppp;S=Lee;"
                      GX409A::x400%"/C=xx/A=aaa/P=ppp/S=Lee"
                              smtp%"postmast@nodeb.bitnet"
              MICKEY::PRFGAT::profs%"NANCY@IBMB"
                              edu%"HU427BD%CSUNIB@abc.acme.edu"

Chapter 5 - Mapping

5.1. Mapping scheme

   DECnet address field is somehow a 'flat land' with some obliged
   routes to reach some hidden areas. Thus a truly hierarchical mapping
   scheme using mapping tables as suitable for RFC822 is not the
   appropriate solution. A fixed set of rules using DDAs support is
   defined in order to define the mapping.

   Another important aspect of the problem is the coexistence of many
   disjoint DECnet networks, using the same DECnet address space, i.e.,
   common X.400 and/or RFC822 mailing system acting as glue to connect
   different isolated Mail-11 islands. Thus, to identify uniquely each
   DECnet network we must also introduce the concept of 'DECnet network
   name', which we will refer shortly as 'net' from now onwards. We
   define as 'net' a unique ASCII string identifying the DECnet network
   we are connected to. To be more specific, the 'net' element will
   identify the DECnet community being served, i.e., it could also
   differ from the actual official network name. Aliases are allowed for
   the

       net = 'HEPnet'       the High Energy Physics DECnet network
       net = 'SPAN'         the Space Physics Analysis Network
       net = 'Enet'         the Digital Equipment Corporate Network

   The need of labelling each DECnet network with its name comes also
   from the requirement to implement the 'intelligent' gateway, i.e.,
   the gateway which is able to understand its ability to connect



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   directly to the specified DECnet network, even if the O/R address
   specify a path to a different gateway. A more detailed discussion of
   the problem is in 5.3 and 5.5.

   A registry of 'net' attributes and their correspondent gateways must
   also be implemented to insure uniqueness of names. A simple table
   coupling 'net' and the gateway address is used, in a syntax similar
   to the 'gate' table used in RFC1327. An example:

        HEPnet#OU$Cosine-gw.O$@.PRMD$infn.ADMD$garr.C$IT#
        SPAN#OU$Cosine-gw.O$@.PRMD$infn.ADMD$garr.C$IT#
        SPAN#O$ESRIN1.PRMD$esa.ADMD$Master400.C$it#

   Ambiguous left entries are allowed. Gateway implementations could
   simply choose among one of them, or try them all in cyclic order to
   obtain better performances.

   In order to keep the mapping rules very simple, avoiding the need to
   analyse Mail-11 addresses to distinguish the 'route', 'node' and
   needed to cover the mapping problem.

5.2. Mail-11 --> X.400

    We define the following Domain Defined Attributes to map a Mail-11
   address:

        DD.Dnet
        DD.Mail-11

   We thus define the mapping rule

        route::node::localpart

   maps into

        C=xx; ADMD=yyy; PRMD=zzz; O=ooo; OU=uuu; DD.Dnet=net;
        DD.Mail-11=route::node::localpart;

   with

        xx  = country code of the gateway performing the conversion
        yyy = Admd of the gateway performing the conversion
        zzz = Prmd of the gateway performing the conversion
        ooo = Organisation of the gateway performing the conversion
        uuu = Org. Unit(s) of the gateway performing the conversion
        net = name of the DECnet network (e.g., HEPnet, SPAN,...)

   ('zzz','ooo','uuu' being used or dropped appropriately in order to



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   identify uniquely within the X.400 MHS the gateway performing the
   conversion).

   The following defaults also apply:

   if 'node' is missing and we are mapping the Mail-11 originator (From)
   then 'node' defaults to the DECnet node name of the gateway (gwnode);

   if 'node' is missing and we are mapping the Mail-11 recipient (To,
   Cc) then 'node' defaults to the DECnet node name of the 'From'
   address.

   if 'DD.Dnet=net' is missing, then it defaults to a value defined
   locally by the gateway: if the gateway is connected to one DECnet
   network only, then 'net' will be the name of this unique network; if
   the gateway is connected to more than one DECnet network, then the
   gateway will establish a 'first choice' DECnet network, and 'net'
   will default to this value.

   In case 'local-part' contains 'x400-text-address' see also section
   6.4.3;

   In case 'local-part' contains 'RFC822-address' see also section
   6.4.4.

5.2.1. Examples

   Let us suppose that:

     the DECnet network name (net) is 'HEP';
     the DECnet node name of the gateway (gwnode) is 'X4TDEC';
     the Country Code of the gateway is 'IT' and its ADMD is 'garr'
     (and these two fields are enough to identify uniquely the gateway
     within the X.400 MHS).

    USER47
     C=it; ADMD=garr; DD.Dnet=HEP; DD.Mail-11=X4TDEC::USER47;

    MYNODE::BETTY
     C=it; ADMD=garr; DD.Dnet=HEP; DD.Mail-11=MYNODE::BETTY;

    BOSTON::CLUS02::GOOFY1::MARY34
     C=it; ADMD=garr; DD.Dnet=HEP; DD.Mail-11=BOSTON::GOOFY1::MARY34;

    UCLA13::MVAX93::MRGATE::"MBOX1::MBX34:MYC3::BOB"
     C=it; ADMD=garr; DD.Dnet=HEP;
     DD.Mail-11=UCLA13::MVAX93::MRGATE::(q)MBOX1::MBX34::MYC3::BOB(q)




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    MIAMI2::George.Rosenthal
     C=it; ADMD=garr; DD.Dnet=HEP; DD.Mail-11=MIAMI2::George.Rosenthal;

    MRGATE::"C=xx::A=bbb::P=ppp::S=Joe"
     C=it; ADMD=garr; DD.Dnet=HEP;
     DD.Mail-11=X4TDEC::MRGATE::(q)C=xx::A=bbb::P=ppp::S=Joe(q)

    MAINVX::In%"path1!path2!user%dom"
     C=it; ADMD=garr; DD.Dnet=HEP;
     DD.Mail-11=MAINVX::In(p)(q)path1(b)path2(b)user(p)dom(q)

5.3. X.400 encoding of Mail-11 --> Mail-11

   In order to assure path reversibility in case of multiple Mail-
   11/X.400 gateway crossing we must distinguish two cases:

   - DD.Dnet=net is known to the gateway as one of the DECnet networks
     it is connected to. In this case the mapping is trivial:

        C=xx; ADMD=yyy; PRMD=zzz; O=ooo; OU=uuu; DD.Dnet=net;
        DD.Mail-11=route::node::localpart;

   (see sect. 5.2 for explication of 'xx','yyy','zzz','ooo','uuu','net')

   maps into

        route::node::localpart

   - DD.Dnet=net is NOT known to the gateway as one of the DECnet
     networks it is connected to. In this case the mapping rule
     described into section 5.4 apply:

        C=xx; ADMD=yyy; PRMD=www; DD.Dnet=net;
        DD.Mail-11=route::node::localpart;

   maps into

        gwnode::gw%"C=xx;ADMD=yyy;PRMD=www;DD.Dnet=net;
        DD.Mail-11=route::node::localpart;"

5.3.1. Examples

   Let us suppose that:

     the DECnet network name (net) is 'HEP';
     the DECnet node name of the gateway (gwnode) is 'X4TDEC';
     the Country Code of the gateway is 'IT' and its ADMD is 'garr';
     (and these two fields are enough to identify uniquely the gateway



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     within the X.400 MHS).

     C=it; ADMD=garr; DD.Dnet=HEP;
     DD.Mail-11=X4TDEC::MRGATE::(q)C=ab::A=dsa::P=qwty::OU=mie::S=Cly(q)
       MRGATE::"C=ab::A=dsa::P=qwty::OU=mie::S=Cly"

     C=it; ADMD=garr; DD.Dnet=EASYNET; DD.Mail-11=ROM01::CARLO;
       X4TDEC::gw%"C=it;ADMD=garr;DD.Dnet=EASYNET;
       DD.Mail-11=ROM01::CARLO;"

   (in the above example 'EASYNET' is supposed to be not connected to
   our gateway located on X4TDEC DECnet node).

5.4. X.400 --> Mail-11

   The mapping of an X.400 O/R address into Mail-11 is done encoding the
   various attributes into the X400-text-address as defined in chapter 4
   of RFC1327, and including this as 'f-address'. A 'f-pref' and a the
   DECnet node name of the gateway.

   Thus

      x400-text-address

   will be encoded like

      gwnode::gw%"x400-text-address"

   having spaces dividing attributes as optional.

5.4.1. Example

   Let us suppose that:

     the DECnet node name of the gateway (gwnode) is 'X4TDEC';

   Thus

      C=gb; ADMD=Gold 400; PRMD=AC.UK; O=ucl; OU=cs; G=Jim; S=Clay;

   will be encoded like

    X4TDEC::gw%"/C=gb/A=Gold 400/P=AC.UK/O=ucl/OU=cs/G=Jim/S=Clay"

   or its equivalent with the ";" notation

    X4TDEC::gw%"C=gb;ADMD=Gold 400;PRMD=AC.UK;O=ucl;OU=cs;G=Jim;S=Clay;"




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5.5. Mail-11 encoding of X.400 --> X.400

   It can happened that Mail-11 is used to relay messages between X.400
   systems; this will mean multiple X.400/Mail-11 gateway crossing and
   we will encounter Mail-11 addresses containing embedded X.400
   informations. In order to assure path reversibility we must then
   distinguish two cases:

   - the embedded X.400 address belongs to a domain whose naming and
     routing rules are known to the global X.400 MHS.  In this case the
     mapping is trivial:

       route::gwnode::gw%"x400-text-address"

   maps into

       x400-text-address

      'route' and 'gwnode' are mapped into X.400 Trace service elements.

   - the encoded X.400 domain does not belong to the global X.400 name
     space. In this case the mapping rule described into section 5.2
     apply:

       route::gwnode::gw%"x400-text-address"

   maps into

       C=xx; ADMD=yyy; DD.Dnet=net;
       DD.Mail-11=route::gwnode::gw(p)(q)x400-text-address(q);

   The latter case  is deprecated and must be regarded as a possible
   temporary solution only, while waiting to include into the global
   X.400 MHS also this domain.

5.5.1. Examples

   Let us suppose that:

     the DECnet network name (net) is 'HEP';
     the DECnet node name of the gateway (gwnode) is 'X4TDEC';
     the Country Code of the gateway is 'IT' and its ADMD is 'garr';
     (and these two fields are enough to identify uniquely the gateway
     within the X.400 MHS).

     X4TDEC::gw%"C=fr;ADMD=atlas;PRMD=ifip;O=poly;S=Moreau;"
       C=fr; ADMD=atlas; PRMD=ifip; O=poly; S=Moreau;




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     X4TDEC::gw%"C=zz;ADMD= ;PRMD=Botwa;O=Miner;S=Chiuaw;"
       C=it; ADMD=garr; DD.Dnet=HEP;
       DD.Mail-11=X4TDEC::gw(p)(q)C=zz;ADMD= ;
       PRMD=Botwa;O=Miner;S=Chiuaw;(q)

   (in the above example  C=zz is unknown to the global X.400 MHS)

Chapter 6 - Complex mapping

6.1. The protocol triangle

   The bilateral mappings described in chapter 5 must be extended in
   order to cover also the case in which also RFC822 addressing is
   involved, and the following triangular situation occurs:

                                   x.400
                                   /  \
                                  /    \
                                 /      \
                             Mail-11----RFC822

   The X.400 - RFC822 side is fully covered by RFC1327, and the previous
   chapters in this document cover the Mail-11 - X.400 side.

   Currently a number of implementations also perform the mapping along
   the Mail-11 - RFC822 side. The most important among these de facto
   standards are discussed in Appendix A, jointly with a Mail-11 -
   RFC822 mapping scheme which covers this side of the triangle.

6.2. RFC822 mapped in Mail-11

   The 'RFC822-address' is usually included in 'local-part' as

        route::gwnode::gw%"rfc822-address"

   an example

        NVXA23::SMTPGW::in%"M.T.Rose@CS.UCLA.edu"

6.3. Mail-11 mapped in RFC822

   There are different styles in mapping a Mail-11 address in RFC822;
   let's have a short summary.

   - Mail-11 address encoded in "Left Hand Side" (LHS) of RFC822
     address, using "%" syntax or "::" syntax;

        route::node::localpart



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   maps to

        localpart%node%route@gw-domains

   or

        "route::node::localpart"@gw-domains

   where 'gw-domains' identify uniquely the Mail-11 / RFC822 gateway.

   - Mail-11 address maps partly to LHS and partly to 'domain' part of
     RFC822 address:

        node::localpart

   maps to

        localpart@node.gw-domains

   - Mail-11 address is completely hidden by a mapping table / directory
     and the resultant RFC822 address contains no trace at all of the
     original address.

   As you could notice, in any of the quoted cases the resultant RFC822
   address is not distinguishable from a genuine RFC822 address.

6.4. Multiple conversions

   Let us now examine briefly the possible situations which involve
   multiple conversions, having one protocol as a relay between the
   other two. This summary suggest some possible enhanced solutions to
   avoid heavy and unduly mappings, but the 'step by step' approach,
   considering blindly one conversion as disjointed to the other, as
   described in the previous sections, can always be used.

6.4.1. X.400 --> RFC822 --> Mail-11

   We apply the RFC1327 rules to the first step, obtaining an RFC822
   address which can be mapped in Mail-11 using the 'f-address' field,
   as described in section 6.2.

   an example:

      C=gb; ADMD=Gold 400; PRMD=AC.UK; O=UCL; OU=cs; G=Jim; S=Clay;

   maps accordingly to RFC1327 to

      Jim.Clay@cs.UCL.AC.UK



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   and finally becomes

      SMTPGW::In%"Jim.Clay@cs.UCL.AC.UK"

   where 'SMTPGW' is the DECnet node name of the machine running the
   RFC822 to Mail-11 gateway.

6.4.2. Mail-11 --> RFC822 --> X.400

   Some of the possible mapping described in section 6.3 apply to the
   Mail-11 address, hiding completely its origin. The RFC1327 apply on
   the last step.

   an example:

      RELAY::MYNODE::BETTY

   could map into RFC822 as

      BETTY%MYNODE@RELAY.dnet.gw1.it

   and accordingly to RFC1327

      C=it; A=garr; P=dom1; O=gw1; OU=RELAY; S=BETTY(p)MYNODE;

   where 'dnet.gw1.it' is the domain of the machine running the Mail-11
   to RFC822 gateway.

6.4.3. X.400 --> Mail-11 --> RFC822

   The X.400 address is stored into Mail-11 'f-address' element as
   described in sections 5.3 and 5.4; then if the Mail-11 to RFC822
   gateway is able to understand the presence of a 'x400-text-address'
   into the Mail-11 address, then it applies RFC1327 to it, and encodes
   header. Otherwise it applies the rules described in 6.3

   an example:

     C=gb; ADMD=Gold 400; PRMD=AC.UK; O=UCL; OU=cs; G=Jim; S=Clay;

   will be encoded like

     X4TDEC::gw%"/C=gb/A=Gold 400/P=AC.UK/O=UCL/OU=cs/G=Jim/S=Clay"

   If the Mail-11 to RFC822 gateway recognise the x400-text-address,
   then the address becomes, accordingly to RFC1327

     Jim.Clay@cs.UCL.AC.UK



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   and the following RFC822 header line is added

     Received: from X4TDEC with DECnet (Mail-11) on xx-xxx-xxxx.

   Otherwise one of the dumb rules could produce

    gw%"/C=gb/A=Gold 400/P=AC.UK/O=UCL/OU=cs/G=Jim/S=Clay"@X4TDEC.doms

6.4.4. RFC822 --> Mail-11 --> X.400

   The RFC822 address is encoded in Mail-11 f-address element as
   described in sect. 6.2; then if the Mail-11 to X.400 gateway is able
   to understand the presence of an 'RFC822-address' into the Mail-11
   address, then it applies RFC1327 to it, and encodes 'route' and
   applies the rules described in 5.2 and 5.5.

   an example:

      Jim.Clay@cs.UCL.AC.UK

   will be encoded like

      SMTPGW::In%"Jim.Clay@cs.UCL.AC.UK"

   If the Mail-11 to X.400 gateway recognise the RFC822-address, then
   the address becomes, accordingly to RFC1327

      C=gb; ADMD=Gold 400; PRMD=AC.UK; O=UCL; OU=cs; G=Jim; S=Clay;

   and a 'trace' record is added into the X.400 P1 data, stating that a
   node named SMTPGW was crossed.

   Otherwise dumb rule produces

      C=it; ADMD=garr; DD.Dnet=HEP;
      DD.Mail-11=SMTPGW::In(p)(q)Jim.Clay(a)cs.UCL.AC.UK(q)

6.4.5. RFC822 --> X.400 --> Mail-11

   We apply RFC1327 to the first conversion, obtaining an X.400 address.
   Then the rules described in sections 5.3 and 5.4 are used to store
   the X.400 address as 'x400-text-address' into the Mail-11

   an example:

      Jim.Clay@cs.UCL.AC.UK

   maps accordingly to RFC1327 to



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      C=gb; ADMD=Gold 400; PRMD=AC.UK; O=UCL; OU=cs; G=Jim; S=Clay;

   and finally becomes

      SMTPGW::gw%"/C=gb/A=Gold 400/P=AC.UK/O=UCL/OU=cs/G=Jim/S=Clay"

   where 'SMTPGW' is the DECnet node name of the machine running the
   X.400 to Mail-11 gateway.

6.4.6. Mail-11 --> X.400 --> RFC822

   The Mail-11 address is encoded as specified in sections 5.2 and 5.5;
   then RFC1327 is used to convert the address in RFC822.

   an example:

      RELAY::MYNODE::BETTY

   maps into X.400 as

      C=it; ADMD=garr; DD.Dnet=HEP; DD.Mail-11=RELAY::MYNODE::BETTY;

   and accordingly to RFC1327

      "/C=it/A=garr/DD.Dnet=HEP/DD.Mail-11=RELAY::MYNODE::BETTY"@gw2.it

   where 'gw2.it' is the domain of the machine running the RFC1327
   gateway.

Appendix A Mail-11 - RFC822 mapping

A.1 Introduction

   The implementation of a Mail-11 - RFC822 gateway was faced by many
   software developers independently, and was included in many mail
   products which were running on both VAX/VMS and UNIX systems. As
   there was not a unique standard mapping way, the implementations
   resulted into a number of possible variant methods to map a Mail-11
   address into an RFC822 one. Some of these products became then
   largely widespread, starting to create a number of de facto mapping
   methods.

   In this small appendix some sort of standardisation of the mapping
   problem is considered, trying to be compatible with the existing
   installed software. We must also remind that, in some cases, only
   simple Mail-11 addresses could be mapped into RFC822, having complex
   ones producing all sort of quite strange results.




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   On the other hand, the mapping of an RFC822 address in Mail-11 was
   quite straightforward, resulting in a common definition which uses
   "Mail-11 foreign mail protocol" to design an RFC822 address:

      [[node::][node::]...]prot%"rfc-822-address"

   or

      [node::][node::]...]::"rfc-822-address"

A.2 De facto implementations

   A considerable number of de-facto implementations of Mail-11/RFC822
   gateways is existing. As said in the introduction, the mapping of
   RFC822 addresses in Mail-11 is accomplished using the foreign mail
   protocol syntax and is thus unique.

   On the other hand, Mail-11 addresses are encoded in RFC822 syntax in
   various ways. Here are the most common ones:

        a) "node::user"@gateway-address
        b) user%node@gateway-address
        c) user@node.decnet.domains
        d) user%node.dnet@gateway-address

   Let's have a quick look to these different choices.

   a - This form simply encloses as quoted Left Hand Side string the
       original Mail-11 address into the RFC822 address of the
       Mail-11/RFC822 gateway. This method is fully conformant with
       RFC822 syntax, and the Mail-11 address is left untouched; thus
       no encoding rules need to applied to it.

   b - As one will immediately notice, this form has nothing in it
       indicating the address is a Mail-11 one; this makes the encoding
       indistinguishable from a similar encoding of RSCS (BITnet)
       addresses used by some IBM VM Mailer systems. It should thus be
       deprecated.

   c - In this case a sort of 'reserved word' (decnet)  embedded into
       the address itself identifies the presence of a Mail-11 original
       address preceding it. The decoding is possible, dropping
       'domains' and extracting 'user' and 'node' parts. However complex
       Mail-11 addresses cannot be mapped properly in this syntax, and
       there is no specific rule for adding the 'domains' part of the
       address.





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   d - In this case again there is a 'reserved word' (dnet)  which make
       possible the identification of the original Mail-11 address;
       'gateway-address' points to the Mail-11/RFC822 gateway and 'node'
       and 'user' information can be easily drawn from the address.
       However complex Mail-11 addresses cannot be embedded easily into
       this syntax.

A.3 Recommended mappings

   From the examples seen in the previous paragraphs we can derive a
   canonical form for representing the mapping between Mail-11 and
   RFC822.

A3.1 RFC822 mapped in Mail-11

   The mapping of an RFC822 address in Mail-11 is straightforward, using
   the "Mail-11 foreign mail protocol" syntax. The two possible variants
   are:

      [[node::][node::]...]prot%"rfc-822-address"

   or

      [node::][node::]...]::"rfc-822-address"

A3.2 Mail-11 mapped in RFC822

   RFC822 foresee a canonical form for representing non-RFC822
   addresses: put the foreign address in local part (Left Hand Side,
   LHS) is a form as similar as possible to its original syntax. Thus
   the suggested mapping is:

      "Mail-11-address"@gateway-address

   This format assures also the return path via the appropriate gateway.

A.4 Conclusions

   A standard way of mapping Mail-11 addresses into RFC822 and vice
   versa is feasible. A suggestion is thus made to unify all existing
   and future implementations. It should be noted, however, that there
   is no way to specify in these mappings the name of the decnet
   community owning the encoded address, as it was done for X.400, thus
   the implementation of the 'intelligent' gateway in this case is
   impossible.






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Acknowledgements

   I wish to thank all those people who read the first draft and
   contributed a lot with their useful suggestions to the revision of
   this document, in particular RARE WG1 and IETF X.400 ops group
   members and S. Hardcastle-Kille.

References

   [1]  CCITT, "CCITT Recommendations X.400-X.430", Message Handling
        Systems: Red Book, October 1984.

   [2]  CCITT, "CCITT Recommendations X.400-X.420", Message Handling
        Systems: Blue Book, November 1988.

   [3]  Crocker, D., "Standard of the Format of ARPA Internet Text
        Messages", STD 11, RFC 822, UDel, August 1982.

   [4]  Kille, S., "Mapping Between X.400 and RFC 822", UK Academic
        Community Report (MG.19) / RFC 987, June 1986.

   [5]  Kille, S., "Mapping Between X.400(1988) / ISO 10021 and RFC
        822", RFC 1327, March 1992.

   [6]  Digital Equipment Corp.;, "VAX/VMS Mail Utility".

   [7]  Joiner Associates Inc., "Jnet User's Manual".

   [8]  PMDF User's Guide.

Security Considerations

   Security issues are not discussed in this memo.

Author's Address

   Claudio Allocchio
   Cosine S2.2
   Sincrotrone Trieste
   Area di Ricerca
   Padriciano 99
   I 34012 Trieste
   Italy

   Phone:   +39 40 3758523
   Fax:     +39 40 226338
   EMail:  Claudio.Allocchio@elettra.Trieste.it
           C=it; A=garr; P=Trieste; O=Elettra; S=Allocchio; G=Claudio;



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