Multiple Language Content Type
RFC 8255

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Internet Engineering Task Force (IETF)                      N. Tomkinson
Request for Comments: 8255                                 N. Borenstein
Category: Standards Track                                 Mimecast, Ltd.
ISSN: 2070-1721                                             October 2017

                     Multiple Language Content Type

Abstract

   This document defines the 'multipart/multilingual' content type,
   which is an addition to the Multipurpose Internet Mail Extensions
   (MIME) standard.  This content type makes it possible to send one
   message that contains multiple language versions of the same
   information.  The translations would be identified by a language tag
   and selected by the email client based on a user's language settings.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8255.

Copyright Notice

   Copyright (c) 2017 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
   (https://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.

Tomkinson & Borenstein       Standards Track                    [Page 1]
RFC 8255             Multiple Language Content Type         October 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  The Content-Type Header Field . . . . . . . . . . . . . . . .   3
   3.  The Message Parts . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  The Multilingual Preface  . . . . . . . . . . . . . . . .   4
     3.2.  The Language Message Parts  . . . . . . . . . . . . . . .   5
     3.3.  The Language-Independent Message Part . . . . . . . . . .   5
   4.  Message Part Selection  . . . . . . . . . . . . . . . . . . .   6
   5.  The Content-Language Field  . . . . . . . . . . . . . . . . .   6
   6.  The Content-Translation-Type Field  . . . . . . . . . . . . .   7
   7.  The Subject Field in the Language Message Parts . . . . . . .   8
   8.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  An Example of a Simple Multiple-Language Email Message  .   8
     8.2.  An Example of a Multiple-Language Email Message with a
           Language-Independent Part . . . . . . . . . . . . . . . .   9
     8.3.  An Example of a Complex Multiple-Language Email Message
           with a Language-Independent Part  . . . . . . . . . . . .  11
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  The 'multipart/multilingual' Media Type . . . . . . . . .  13
     9.2.  The Content-Translation-Type Field  . . . . . . . . . . .  15
     9.3.  The Content-Translation-Type Header Field Values  . . . .  15
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  16
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  16
     11.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19

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 multicultural cities and have formed departments and teams
   that span continents, cultures, and languages.  Thus, the need to
   communicate efficiently with little margin for miscommunication has
   grown significantly.

   This document defines the 'multipart/multilingual' content type,
   which is an addition to the Multipurpose Internet Mail Extensions