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Versions: 00 01                                                         
IETF                                                        N. Tomkinson
Internet-Draft                                             N. Borenstein
Intended status: Standards Track                            Mimecast Ltd
Expires: October 18, 2014                                   Apr 16, 2014


                     Multiple Language Content Type
                  draft-tomkinson-multilangcontent-01

Abstract

   This document defines an addition to the Multipurpose Internet Mail
   Extensions (MIME) standard to make it possible to send one message
   that contains multiple language versions of the same information.
   The translations would be identified by a language code and selected
   by the email client based on a user's language settings or locale.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 18, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



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1.  Introduction

   Since the invention of email and the rapid spread of the internet,
   more and more people have been able to communicate in more and more
   countries and in more and more languages.  But during this time of
   technological evolution, email has remained a single language
   communication tool, whether it is English to English, Spanish to
   Spanish or Japanese to Japanese.

   Also during this time, many corporations have established their
   offices in multi-cultural cities and formed departments and teams
   that span continents, cultures and languages so the need to
   communicate efficiently with little margin for miscommunication has
   grown exponentially.

   The objective of this document is to define an addition to the widely
   used Multipurpose Internet Mail Extensions (MIME) standard, to make
   it possible to send a single message to a group of people in such a
   way that all of the recipients can read the email in their own first
   language.  The methods of translation of the message content are
   beyond the scope of this document, but the structure of the email
   itself is presented herein.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].


2.  The Content-Type Header

   When there is a requirement to send a message in a number of
   different languages and the translations are to be embedded in the
   same message, the multipart subtype "multipart/multilingual" SHOULD
   be used to help the receiving email client make sense of the message
   structure.

   The suggested multipart subtype "multipart/multilingual" has the same
   semantics as "multipart/alternative" (as discussed in RFC 2046
   [RFC2046]) in that each of the body parts is an alternative version
   of the same information.  The primary difference between "multipart/
   multilingual" and "multipart/alternative" is that when using
   "multipart/multilingual", the message part to select for rendering is
   chosen based on the value of the Content-Language header instead of
   the ordering of the parts and the Content-Types.

   The syntax for this multipart subtype conforms to the common syntax



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   for subtypes of multipart given in section 5.1.1. of RFC 2046
   [RFC2046], therefore, an example "multipart/multilingual" Content-
   Type header field would look like this:

   Content-type: multipart/multilingual; boundary=01189998819991197253


3.  The Multilingual Preface -- the first message part

   In order for the message to be received and displayed in non-
   conforming email clients, the message MUST contain an explanatory
   message part which MUST-NOT be marked with a Content-Language header
   but MUST be the first of the message parts.  Because non-conforming
   email clients are expected to treat the message as multipart/mixed
   (in accordance with sections 5.1.3 and 5.1.7 of RFC 2046 [RFC2046])
   they may show all of the message parts sequentially or as
   attachments.  Including and showing this explanatory part will help
   the message recipient understand the message structure.

   This initial message part SHOULD explain briefly to the message
   recipient that the message contains multiple languages and the parts
   may be rendered sequentially or as attachments.  This SHOULD be
   presented in the same languages that are provided in the subsequent
   message parts.

   Whilst this section of the message is useful for backward
   compatibility, it SHOULD only be shown when rendered by a non-
   conforming email client because conforming email client SHOULD only
   show the single message part identified by the user's preferred
   language (or locale) and the message part's Content-Language.


4.  The Subsequent Message Parts

   The subsequent message parts are translations of the same message
   content.  These body parts MAY be ordered so that the first part
   after the multilingual preface is in the language believed to be the
   most likely to be recognised by recipients using software that does
   not implement multipart/multilingual.

   The Content-Type for each individual language part MAY be any MIME
   type (including multipart subtypes such as multipart/alternative).
   However, it is recommended that the Content-Type of the language
   parts is kept as simple as possible for interoperability with
   existing email clients.  The language parts are not required to have
   matching Content-Types or multipart structures.  For example, there
   might be an English part of type "text/html" followed by a Spanish
   part of type "application/pdf" followed by a Chinese part of type



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   "image/jpeg".  Whatever the content-type, the contents SHOULD be
   composed for optimal viewing in the specified language.


5.  The Content-Language Header

   The Content-Language header in the individual multipart message parts
   is used to identify the language in which the message part is
   written.  Based on the value of this header, a conforming email
   client can determine which message part to display (given the user's
   language settings or locale).

   The Content-Language MUST comply with RFC 3282 [RFC3282] (which
   defines the Content-Language header) and BCP 47/RFC 5646 [RFC5646]
   (which defines the structure and semantics for the language code
   values).  Examples of this header for English, English as used in the
   United States and Latin American Spanish, could look like the
   following:

   Content-Language: en

   Content-Language: en-US

   Content-Language: es-419


6.  The Subject-Translation Header

   On receipt of the message, conforming email clients will need to
   select the correct multipart message content and replace the subject
   that is shown to the message recipient with the translated subject.
   To enable this the Subject-Translation header SHOULD be provided in
   each message part that contains a Content-Language header.

   The value for this header should be a simple translated version of
   the original email subject.  An example of this header may look like
   this:

   Subject-Translation: Mensaje de ejemplo para varios idiomas


7.  Examples

7.1.  An Example of a Simple Multiple language email message

   Below is an example of a simple multiple language email message
   formatted using the method detailed in this document.




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   From: Nik
   To: Nathaniel
   Subject:  Simple example multiple language message
   Content-type: multipart/multilingual; boundary=01189998819991197253

   --01189998819991197253

   This is a message in two languages: English and Spanish.  It says the
   same thing in each language.  If you read it in the first language,
   you can ignore the other translations. The other translations may be
   presented as attachments or grouped together.

   Este es un mensaje en dos idiomas: Ingles y Espanol. Dice lo mismo en
   cada idioma. Si lo necesita en el primer idioma, puede ignorar el
   otras traducciones. Las otras traducciones se pueden presentar como
   archivos adjuntos o agrupados.

   --01189998819991197253
   Content-Language: en
   Content-Type: text/plain
   Subject-Translation: Simple example multiple language message

   Hello, this message content is provided in your language.

   --01189998819991197253
   Content-Language: es
   Content-Type: text/plain
   Subject-Translation: Ejemplo simple mensaje en varios idiomas

   Hola, el contenido de este mensaje esta disponible en su idioma.

   --01189998819991197253--

7.2.  An Example of a Complex Multiple language email message

   Below is an example of a more complex multiple language email message
   formatted using the method detailed in this document.  Note that the
   language parts have multipart contents and would therefore require
   further processing to determine the content to display.


   From: Nik
   To: Nathaniel
   Subject:  Complex example multiple language message
   Content-type: multipart/multilingual; boundary=01189998819991197253

   --01189998819991197253




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   This is a message in two languages: English and Spanish.  It says the
   same thing in each language.  If you read it in the first language,
   you can ignore the other translations. The other translations may be
   presented as attachments or grouped together.

   Este es un mensaje en dos idiomas: Ingles y Espanol. Dice lo mismo en
   cada idioma. Si lo necesita en el primer idioma, puede ignorar el
   otras traducciones. Las otras traducciones se pueden presentar como
   archivos adjuntos o agrupados.

   --01189998819991197253
   Content-Language: en
   Content-Type: multipart/alternative; boundary=multipartaltboundary
   Subject-Translation: Complex example multiple language message

   --multipartaltboundary
   Content-Type: text/plain

   Hello, this message content is provided in your language.

   --multipartaltboundary
   Content-Type: text/html

   <html><body><p>Hello, this message content is provided in your
   language.<p></body></html>

   --multipartaltboundary--

   --01189998819991197253
   Content-Language: es
   Content-Type: multipart/mixed; boundary=multipartmixboundary
   Subject-Translation: Ejemplo complejo mensaje en varios idiomas

   --multipartmixboundary
   Content-Type:application/pdf

   ..PDF file in Spanish here..

   --multipartmixboundary
   Content-Type:image/jpeg

   ..JPEG image showing Spanish content here..

   --multipartmixboundary--

   --01189998819991197253--





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8.  Acknowledgements

   The authors are grateful for the helpful input received from many
   people but would especially like to acknowledge the help of Harald
   Alvestrand, Mark Davis, Doug Ewell, Fiona Tomkinson and Simon Tyler.


9.  IANA Considerations

   The multipart/multilingual MIME type will be registered with IANA.


10.  Security Considerations

   This document has no additional security considerations beyond those
   that apply to the standards and procedures on which it is built.


11.  Normative References

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3282]  Alvestrand, H., "Content Language Headers", RFC 3282,
              May 2002.

   [RFC5646]  Phillips, A. and M. Davis, "Tags for Identifying
              Languages", BCP 47, RFC 5646, September 2009.


Authors' Addresses

   Nik Tomkinson
   Mimecast Ltd
   CityPoint, One Ropemaker Street
   London,   EC2Y 9AW
   United Kingdom

   Email: rfc.nik.tomkinson@gmail.com








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   Nathaniel Borenstein
   Mimecast Ltd
   480 Pleasant Street
   Watertown,   MA 02472
   North America

   Email: nsb@mimecast.com












































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