Internationalized Email Headers
RFC 6532
Document | Type |
RFC - Proposed Standard
(February 2012; Errata)
Obsoletes RFC 5335
Updates RFC 2045
|
|
---|---|---|---|
Authors | Abel Yang , Shawn Steele , Ned Freed | ||
Last updated | 2020-01-21 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized with errata bibtex | ||
Reviews | |||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6532 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Pete Resnick | ||
Send notices to | alexey.melnikov@isode.com |
Internet Engineering Task Force (IETF) A. Yang Request for Comments: 6532 TWNIC Obsoletes: 5335 S. Steele Updates: 2045 Microsoft Category: Standards Track N. Freed ISSN: 2070-1721 Oracle February 2012 Internationalized Email Headers Abstract Internet mail was originally limited to 7-bit ASCII. MIME added support for the use of 8-bit character sets in body parts, and also defined an encoded-word construct so other character sets could be used in certain header field values. However, full internationalization of electronic mail requires additional enhancements to allow the use of Unicode, including characters outside the ASCII repertoire, in mail addresses as well as direct use of Unicode in header fields like "From:", "To:", and "Subject:", without requiring the use of complex encoded-word constructs. This document specifies an enhancement to the Internet Message Format and to MIME that allows use of Unicode in mail addresses and most header field content. This specification updates Section 6.4 of RFC 2045 to eliminate the restriction prohibiting the use of non-identity content-transfer- encodings on subtypes of "message/". 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 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6532. Yang, et al. Standards Track [Page 1] RFC 6532 Internationalized Email Headers February 2012 Copyright Notice Copyright (c) 2012 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology Used in This Specification . . . . . . . . . . . . 3 3. Changes to Message Header Fields . . . . . . . . . . . . . . . 4 3.1. UTF-8 Syntax and Normalization . . . . . . . . . . . . . . 4 3.2. Syntax Extensions to RFC 5322 . . . . . . . . . . . . . . 5 3.3. Use of 8-bit UTF-8 in Message-IDs . . . . . . . . . . . . 5 3.4. Effects on Line Length Limits . . . . . . . . . . . . . . 5 3.5. Changes to MIME Message Type Encoding Restrictions . . . . 6 3.6. Use of MIME Encoded-Words . . . . . . . . . . . . . . . . 6 3.7. The message/global Media Type . . . . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . . 10 Yang, et al. Standards Track [Page 2] RFC 6532 Internationalized Email Headers February 2012 1. Introduction Internet mail distinguishes a message from its transport and further divides a message between a header and a body [RFC5322]. Internet mail header field values contain a variety of strings that are intended to be user-visible. The range of supported characters for these strings was originally limited to [ASCII] in 7-bit form. MIME [RFC2045] [RFC2046] [RFC2047] provides the ability to use additional character sets, but this support is limited to body part data and to special encoded-word constructs that were only allowed in a limited number of places in header field values. Globalization of the Internet requires support of the much larger setShow full document text