draft-ietf-eai-rfc5335bis-02.txt   draft-ietf-eai-rfc5335bis-03.txt 
Email Address Internationalization A. Yang Email Address Internationalization A. Yang
(EAI) TWNIC (EAI) TWNIC
Internet-Draft S. Steele Internet-Draft S. Steele
Obsoletes: 5335 (if approved) Microsoft Obsoletes: 5335 (if approved) Microsoft
Updates: 2045, 5322 August 19, 2010 Updates: 2045,5321,5322 October 22, 2010
(if approved) (if approved)
Intended status: Standards Track Intended status: Standards Track
Expires: February 20, 2011 Expires: April 25, 2011
Internationalized Email Headers Internationalized Email Headers
draft-ietf-eai-rfc5335bis-02 draft-ietf-eai-rfc5335bis-03
Abstract Abstract
Full internationalization of electronic mail requires not only the Full internationalization of electronic mail requires not only the
capabilities to transmit non-ASCII content, to encode selected capabilities to transmit non-ASCII content, to encode selected
information in specific header fields, and to use non-ASCII information in specific header fields, and to use non-ASCII
characters in envelope addresses. It also requires being able to characters in envelope addresses. It also requires being able to
express those addresses and the information based on them in mail express those addresses and the information based on them in mail
header fields. This document specifies an variant of Internet mail header fields. This document specifies a variant of Internet mail
that permits the use of Unicode encoded in UTF-8, rather than ASCII, that permits the use of Unicode encoded in UTF-8, rather than ASCII,
as the base form for Internet email header field. This form is as the base form for Internet email header field. This form is
permitted in transmission only if authorized by an SMTP extension, as permitted in transmission only if authorized by an SMTP extension, as
specified in an associated specification. This specification Updates specified in an associated specification. This specification updates
section 6.4 of [RFC2045] to conform with the requirements. Section 6.4 of [RFC2045] to conform with the requirements.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 20, 2011. This Internet-Draft will expire on April 25, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 27 skipping to change at page 2, line 27
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Role of This Specification . . . . . . . . . . . . . . . . 3 1.1. Role of This Specification . . . . . . . . . . . . . . . . 3
1.2. Relation to Other Standards . . . . . . . . . . . . . . . 3 1.2. Relation to Other Standards . . . . . . . . . . . . . . . 3
2. Background and History . . . . . . . . . . . . . . . . . . . . 3 2. Background and History . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Changes on Message Header Fields . . . . . . . . . . . . . . . 5 4. Changes on Message Header Fields . . . . . . . . . . . . . . . 5
4.1. UTF-8 Syntax and Normalization . . . . . . . . . . . . . . 5 4.1. UTF-8 Syntax and Normalization . . . . . . . . . . . . . . 5
4.2. Changes on MIME Headers . . . . . . . . . . . . . . . . . 6 4.2. Changes on MIME Headers . . . . . . . . . . . . . . . . . 6
4.3. Syntax Extensions to RFC 5322 . . . . . . . . . . . . . . 6 4.3. Syntax Extensions to RFC 5322 . . . . . . . . . . . . . . 6
4.4. Change on addr-spec Syntax . . . . . . . . . . . . . . . . 8 4.4. Change on addr-spec Syntax . . . . . . . . . . . . . . . . 8
4.5. Trace Field Syntax . . . . . . . . . . . . . . . . . . . . 8 4.5. Trace Field Syntax . . . . . . . . . . . . . . . . . . . . 9
4.6. message/global . . . . . . . . . . . . . . . . . . . . . . 9 4.6. message/global . . . . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
8. Edit history . . . . . . . . . . . . . . . . . . . . . . . . . 12 8. Edit history . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. draft-ietf-eai-rfc5335bis-00 . . . . . . . . . . . . . . . 12 8.1. draft-ietf-eai-rfc5335bis-00 . . . . . . . . . . . . . . . 12
8.2. draft-ietf-eai-rfc5335bis-01 . . . . . . . . . . . . . . . 12 8.2. draft-ietf-eai-rfc5335bis-01 . . . . . . . . . . . . . . . 12
8.3. draft-ietf-eai-rfc5335bis-02 . . . . . . . . . . . . . . . 12 8.3. draft-ietf-eai-rfc5335bis-02 . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.4. draft-ietf-eai-rfc5335bis-03 . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
1.1. Role of This Specification 1.1. Role of This Specification
Full internationalization of electronic mail requires several Full internationalization of electronic mail requires several
capabilities: capabilities:
o The capability to transmit non-ASCII content, provided for as part o The capability to transmit non-ASCII content, provided for as part
of the basic MIME specification [RFC2045], [RFC2046]. of the basic MIME specification [RFC2045], [RFC2046].
o The capability to use international characters in envelope o The capability to use international characters in envelope
addresses, discussed in [I-D.ietf-eai-frmwrk-4952bis] and addresses, discussed in [I-D.ietf-eai-frmwrk-4952bis] and
specified in [I-D.yao-eai-rfc5336bis]. specified in [I-D.ietf-eai-rfc5336bis].
o The capability to express those addresses, and information related o The capability to express those addresses, and information related
to them and based on them, in mail header fields, defined in this to them and based on them, in mail header fields, defined in this
document. document.
This document specifies an variant of Internet mail that permits the This document specifies a variant of Internet mail that permits the
use of Unicode encoded in UTF-8 [RFC3629], rather than ASCII, as the use of Unicode encoded in UTF-8 [RFC3629], rather than ASCII, as the
base form for Internet email header fields. This form is permitted base form for Internet email header fields. This form is permitted
in transmission, if authorized by the SMTP extension specified in in transmission, if authorized by the SMTP extension specified in
[I-D.yao-eai-rfc5336bis] or by other transport mechanisms capable of [I-D.ietf-eai-rfc5336bis] or by other transport mechanisms capable of
processing it. processing it.
1.2. Relation to Other Standards 1.2. Relation to Other Standards
This document updates Section 6.4 of [RFC2045]. It removes the This document updates Section 6.4 of [RFC2045]. It removes the
blanket ban on applying a content-transfer-encoding to all subtypes blanket ban on applying a content-transfer-encoding to all subtypes
of message/, and instead specifies that a composite subtype MAY of message/, and instead specifies that a composite subtype MAY
specify whether or not a content-transfer-encoding can be used for specify whether or not a content-transfer-encoding can be used for
that subtype, with "cannot be used" as the default. that subtype, with "cannot be used" as the default.
This document also updates [RFC5322] and MIME ([RFC2045]), and people This document also updates [RFC5322] and MIME ([RFC2045]).
who participate in the experiment have to swich to this document.
Allowing use of a content-transfer-encoding on subtypes of messages Allowing use of a content-transfer-encoding on subtypes of messages
is not limited to transmissions that are authorized by the SMTP is not limited to transmissions that are authorized by the SMTP
extension specified in [I-D.yao-eai-rfc5336bis]. Message/global (see extension specified in [I-D.ietf-eai-rfc5336bis]. message/global (see
Section 4.6) permits use of a content-transfer-encoding. Section 4.6) permits use of a content-transfer-encoding.
2. Background and History 2. Background and History
Mailbox names often represent the names of human users. Many of Mailbox names often represent the names of human users. Many of
these users throughout the world have names that are not normally these users throughout the world have names that are not normally
expressed with just the ASCII repertoire of characters, and would expressed with just the ASCII repertoire of characters, and would
like to use more or less their real names in their mailbox names. like to use more or less their real names in their mailbox names.
These users are also likely to use non-ASCII text in their common These users are also likely to use non-ASCII text in their common
names and subjects of email messages, both received and sent. This names and subjects of email messages, both received and sent. This
protocol specifies UTF-8 as the encoding to represent email header protocol specifies UTF-8 as the encoding to represent email header
field bodies. field bodies.
The traditional format of email messages [RFC5322] allows only ASCII The traditional format of email messages [RFC5322] allows only ASCII
characters in the header fields of messages. This prevents users characters in the header fields of messages. This prevents users
from having email addresses that contain non-ASCII characters. It from having email addresses that contain non-ASCII characters. It
further forces non-ASCII text in common names, comments, and in free further forces non-ASCII text in common names, comments, and in free
text (such as in the Subject: field) to be encoded (as required by text (such as in the "Subject:" field) to be encoded (as required by
MIME format [RFC2047]). This specification describes a change to the MIME format [RFC2047]). This specification describes a change to the
email message format that is related to the SMTP message transport email message format that is related to the SMTP message transport
change described in the associated document change described in the associated documents
[I-D.ietf-eai-frmwrk-4952bis] and [I-D.yao-eai-rfc5336bis], and that [I-D.ietf-eai-frmwrk-4952bis] and [I-D.ietf-eai-rfc5336bis], and that
allows non-ASCII characters in most email header fields. These allows non-ASCII characters in most email header fields. These
changes affect SMTP clients, SMTP servers, mail user agents (MUAs), changes affect SMTP clients, SMTP servers, mail user agents (MUAs),
list expanders, gateways to other media, and all other processes that list expanders, gateways to other media, and all other processes that
parse or handle email messages. parse or handle email messages.
As specified in [I-D.yao-eai-rfc5336bis], an SMTP protocol extension As specified in [I-D.ietf-eai-rfc5336bis], an SMTP protocol extension
"UTF8SMTPbis" is used to prevent the transmission of messages with "UTF8SMTPbis" is used to prevent the transmission of messages with
UTF-8 header fields to systems that cannot handle such messages. UTF-8 header fields to systems that cannot handle such messages.
[[Note in Draft: Keyword related to UTF8SMTP will be decided by WG [[Note in Draft: Keyword related to UTF8SMTP will be decided by WG
before publication.]] before publication.]]
Use of this SMTP extension helps prevent the introduction of such Use of this SMTP extension helps prevent the introduction of such
messages into message stores that might misinterpret, improperly messages into message stores that might misinterpret, improperly
display, or mangle such messages. It should be noted that using an display, or mangle such messages. It should be noted that using an
ESMTP extension does not prevent transferring email messages with ESMTP extension does not prevent transferring email messages with
UTF-8 header fields to other systems that use the email format for UTF-8 header fields to other systems that use the email format for
messages and that may not be upgraded, such as unextended POP and messages and that may not be upgraded, such as unextended POP and
IMAP servers. Changes to these protocols to handle UTF-8 header IMAP servers. Changes to these protocols to handle UTF-8 header
fields are addressed in [RFC5721]-bis and [RFC5738]-bis. fields are addressed in [RFC5721bis] and [RFC5738bis]. [[Note in
Draft: RFC5721bis and RFC5738bis did not yet posted.]]
The objective for this protocol is to allow UTF-8 in email header The objective for this protocol is to allow UTF-8 in email header
fields. fields.
3. Terminology 3. Terminology
A plain ASCII string is also a valid UTF-8 string; see [RFC3629]. In A plain ASCII string is also a valid UTF-8 string; see [RFC3629]. In
this document, ordinary ASCII characters are UTF-8 characters if they this document, ordinary ASCII characters are UTF-8 characters if they
are in headers which contain <utf8-xtra-char>s. are in headers which contain <utf8-xtra-char>s.
Unless otherwise noted, all terms used here are defined in [RFC5321], Unless otherwise noted, all terms used here are defined in [RFC5321],
[RFC5322], [I-D.ietf-eai-frmwrk-4952bis],or [I-D.yao-eai-rfc5336bis]. [RFC5322], [I-D.ietf-eai-frmwrk-4952bis], or
[I-D.ietf-eai-rfc5336bis].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
4. Changes on Message Header Fields 4. Changes on Message Header Fields
SMTP clients can send header fields in UTF-8 format, if the SMTP clients can send header fields in UTF-8 format, if the
UTF8SMTPbis extension is advertised by the SMTP server or is UTF8SMTPbis extension is advertised by the SMTP server or is
permitted by other transport mechanisms. permitted by other transport mechanisms.
This protocol does NOT change the [RFC5322] rules for defining header This protocol does NOT change the [RFC5322] rules for defining header
field names. The bodies of header fields are allowed to contain field names. The bodies of header fields are allowed to contain
UTF-8 characters, but the header field names themselves must contain UTF-8 characters, but the header field names themselves must contain
only ASCII characters. only ASCII characters.
To permit UTF-8 characters in field values, the header definition in To permit UTF-8 characters in field values, the header definition in
[RFC5322] must be extended to support the new format. The following [RFC5322] is extended to support the new format. The following ABNF
ABNF is defined to substitute those definitions in [RFC5322]. is defined to substitute those definitions in [RFC5322].
The syntax rules not covered in this section remain as defined in The syntax rules not covered in this section remain as defined in
[RFC5322]. [RFC5322].
4.1. UTF-8 Syntax and Normalization 4.1. UTF-8 Syntax and Normalization
UTF-8 characters can be defined in terms of octets using the UTF-8 characters can be defined in terms of octets using the
following ABNF [RFC5234], taken from [RFC3629]: following ABNF [RFC5234], taken from [RFC3629]:
UTF8-xtra-char = UTF8-2 / UTF8-3 / UTF8-4 UTF8-xtra-char= UTF8-2 / UTF8-3 / UTF8-4
UTF8-2 = %xC2-DF UTF8-tail UTF8-2 = %xC2-DF UTF8-tail
UTF8-3 = %xE0 %xA0-BF UTF8-tail / UTF8-3 = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2(UTF8-tail) /
%xE1-EC 2(UTF8-tail) / %xED %x80-9F UTF8-tail / %xEE-EF 2(UTF8-tail)
%xED %x80-9F UTF8-tail /
%xEE-EF 2(UTF8-tail)
UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
%xF1-F3 3( UTF8-tail ) / %xF4 %x80-8F 2( UTF8-tail )
%xF4 %x80-8F 2( UTF8-tail )
UTF8-tail = %x80-BF UTF8-tail = %x80-BF
These are normatively defined in [RFC3629], but kept in this document These are normatively defined in [RFC3629], but kept in this document
for reasons of convenience. for reasons of convenience.
See [RFC5198] for a discussion of normalization; the use of See [RFC5198] for a discussion of normalization; the use of
normalization form NFC is RECOMMENDED. Actually, if one is going to normalization form NFC is RECOMMENDED. Actually, if one is going to
do internationalization properly, one of the most often-cited goals do internationalization properly, one of the most often-cited goals
is to permit people to spell their names correctly. Since many is to permit people to spell their names correctly. Since many
mailbox local parts reflect personal names, that principle applies as mailbox local parts reflect personal names, that principle applies as
well. And NFKC is not recommended because it may lose information well. And NFKC is not recommended because it may lose information
skipping to change at page 6, line 31 skipping to change at page 6, line 30
occur. This is expected to be rarely seen in practice, and the occur. This is expected to be rarely seen in practice, and the
potential complexity of other ways of dealing with the issue are potential complexity of other ways of dealing with the issue are
thought to be larger than the complexity of allowing nested encodings thought to be larger than the complexity of allowing nested encodings
where necessary. where necessary.
4.3. Syntax Extensions to RFC 5322 4.3. Syntax Extensions to RFC 5322
The following rules are intended to extend the corresponding rules in The following rules are intended to extend the corresponding rules in
[RFC5322] in order to allow UTF-8 characters. [RFC5322] in order to allow UTF-8 characters.
FWS = <see [RFC5322], folding white space> FWS = <see [RFC5322] Section 3.2.2, folding white space>
CFWS = <see [RFC5322], folding white space> CFWS = <see [RFC5322] Section 3.2.2>
ctext =/ UTF8-xtra-char ctext =/ UTF8-xtra-char
utext =/ UTF8-xtra-char utext =/ UTF8-xtra-char
comment = "(" *([FWS] uCcontent) [FWS] ")" comment = "(" *([FWS] uCcontent) [FWS] ")"
word = uAtom / uQuoted-String word = uAtom / uQuoted-String
This means that all the [RFC5322] constructs that build upon these This means that all the [RFC5322] constructs that build upon these
will permit UTF-8 characters, including comments and quoted strings. will permit UTF-8 characters, including comments and quoted strings.
We do not change the syntax of <atext> in order to allow UTF-8 We do not change the syntax of <atext> in order to allow UTF-8
characters in <addr-spec>. This would also allow UTF-8 characters in characters in <addr-spec>. This would also allow UTF-8 characters in
<message-id>, which is not allowed due to the limitation described in <message-id>, which is not allowed due to the limitation described in
Section 4.5. Instead, <uAtext> is added to meet this requirement. Section 4.5. Instead, <uAtext> is added to meet this requirement.
uText = %d1-9 / ; all UTF-8 characters except uText = %d1-9 / ; all UTF-8 characters except
%d11-12 / ; US-ASCII NUL, CR, and LF %d11-12 / ; US-ASCII NUL, CR, and LF
%d14-127 / %d14-127 /
UTF8-xtra-char UTF8-xtra-char
uQuoted-Pair = ("\" uText) / obs-qp uQuoted-Pair = ("\" uText) / obs-qp
uQcontent = uQtext / uQuoted-Pair uQcontent = uQtext / uQuoted-Pair
uQuoted-String = [CFWS] uQuoted-String = [CFWS] DQUOTE *([FWS] uQcontent) [FWS] DQUOTE [CFWS]
DQUOTE *([FWS] uQcontent) [FWS] DQUOTE
[CFWS]
uCcontent = ctext / uQuoted-Pair / comment DQUOTE = <See appendix B.1 of RFC 5234>
uQtext = qtext / UTF8-xtra-char
uAtext = ALPHA / DIGIT / uCcontent = ctext / uQuoted-Pair / comment
"!" / "#" / ; Any character except
"$" / "%" / ; controls, SP, and specials.
"&" / "'" / ; Used for atoms.
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~" /
UTF8-xtra-char
uAtom = [CFWS] 1*uAtext [CFWS] uQtext = qtext / UTF8-xtra-char
uDot-Atom = [CFWS] uDot-Atom-text [CFWS] uAtext = ALPHA / DIGIT /
"!" / "#" / ; Any character except
"$" / "%" / ; controls, SP, and specials.
"&" / "'" / ; Used for atoms.
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~" /
UTF8-xtra-char
uAtom = FWS] 1*uAtext [CFWS]
uDot-Atom = CFWS] uDot-Atom-text [CFWS]
uDot-Atom-text = 1*uAtext *("." 1*uAtext) uDot-Atom-text = 1*uAtext *("." 1*uAtext)
qcontent = uQcontent qcontent = uQcontent
To allow the use of UTF-8 in a Content-Description header field To allow the use of UTF-8 in a Content-Description header field
[RFC2045], the following syntax is used: [RFC2045], the following syntax is used:
description = "Content-Description:" unstructured CRLF description = "Content-Description:" unstructured CRLF
The <utext> syntax is extended above to allow UTF-8 in all The <utext> syntax is extended above to allow UTF-8 in all
<unstructured> header fields. <unstructured> header fields.
Note, however, this does not remove any constraint on the character Note, however, this does not remove any constraint on the character
set of protocol elements; for instance, all the allowed values for set of protocol elements; for instance, all the allowed values for
timezone in the Date: headers are still expressed in ASCII. And timezone in the "Date:" headers are still expressed in ASCII. And
also, none of this revised syntax changes what is allowed in a also, none of this revised syntax changes what is allowed in a
<message-id>, which will still remain in pure ASCII. <message-id>, which will still remain in pure ASCII.
4.4. Change on addr-spec Syntax 4.4. Change on addr-spec Syntax
Internationalized email addresses are represented in UTF-8. Thus, Internationalized email addresses are represented in UTF-8. Thus,
all header fields containing <mailbox>es are updated to permit UTF-8 all header fields containing <mailbox>es are updated from [RFC5321]
addresses. Section 4.1.2 to permit UTF-8 addresses.
mailbox = name-addr / addr-spec / uAddr-Spec mailbox = name-addr / addr-spec / uAddr-Spec
; Replace mailbox in Section 3.4.1 of RFC 5322
angle-addr =/ [CFWS] "<" uAddr-Spec">" [CFWS] / obs-angle-addr
; Replace angle-addr in Section 3.4 of RFC 5322
angle-addr =/ [CFWS] "<" uAddr-Spec">" [CFWS] / uAddr-Spec = uLocal-Part "@" uDomain
obs-angle-addr
uAddr-Spec = uLocal-Part "@" uDomain uLocal-Part = uDot-String / uQuoted-String
; Replace Local-Part in Section 3.4.1 of RFC 5322
uLocal-Part = uDot-String / uQuoted-String uDot-string = uAtom *("." uAtom)
uQuoted-String = DQUOTE *uQcontent DQUOTE uDomain uDomain = (sub-udomain 1*("." sub-uDomain)) /
= (sub-uDomain 1*("." sub-uDomain)) / address-literal dot-atom / domain-literal / obs-domain
; Replace Domain in Section 4.1.2 of RFC 5321
sub-udomain = uLet-dig [uLdh-str]
; Replace sub-domain in Section 4.1.2 of RFC 5321
uLet-dig = Let-dig / UTF8-xtra-char
; Replace uLet-dig in Section 4.1.2 of RFC 5321
Let-dig = <See Section 4.1.3 of RFC 5321>
uLdh-str = *( ALPHA / DIGIT / "-" / UTF8-xtra-char) uLet-dig
; Replace Ldh-str Section 4.1.2 of RFC 5321
Below are a few examples of possible <mailbox> representations. Below are a few examples of possible <mailbox> representations.
"DISPLAY_NAME" <ASCII@ASCII> "DISPLAY_NAME" <ASCII@ASCII>
; traditional mailbox format ; traditional mailbox format
"DISPLAY_NAME" <non-ASCII@non-ASCII> "DISPLAY_NAME" <non-ASCII@non-ASCII>
; message will bounce if UTF8SMTPbis extension is not supported ; message will bounce if UTF8SMTPbis extension is not supported
<non-ASCII@non-ASCII> <non-ASCII@non-ASCII>
; without DISPLAY_NAME and quoted string ; without DISPLAY_NAME and quoted string
; message will bounce if UTF8SMTPbis extension is not supported ; message will bounce if UTF8SMTPbis extension is not supported
4.5. Trace Field Syntax 4.5. Trace Field Syntax
"For" fields containing internationalized addresses are allowed, by The uFor ( described in [I-D.ietf-eai-rfc5336bis] Section 3.6.3 ))
use of the new uFor syntax. UTF-8 information may be needed in has been added to allow the use of internationalized addresses in
Received fields. Such information is therefore allowed to preserve "For" fields. by use of the new uFor syntax. UTF-8 information may
the integrity of those fields. The uFor syntax retains the original be needed in "Received:" fields. Such information is therefore
UTF-8 email address between email address internationalization EAI- allowed to preserve the integrity of those fields. The uFor syntax
aware MTAs. retains the original UTF-8 email address between email address
internationalization EAI-aware MTAs.
The "Return-Path" header field provides the email return address in The "Return-path" designates the address to which messages indicating
the mail delivery. Thus, the header is augmented to carry UTF-8 non-delivery or other mail system failures are to be sent. Thus, the
addresses (see the revised syntax of <angle-addr> in Section 4.4 of header is augmented to carry UTF-8 addresses (see the revised syntax
this document). This will not break the rule of trace field of <angle-addr> in Section 4.4 of this document). This will not
integrity, because the header field is added at the last MTA and break the rule of trace field integrity, because the header field is
described in [RFC5321]. added at the last MTA and described in [RFC5321].
The <item-value> on "Received:" syntax is augmented to allow UTF-8 The <item-value> on "Received:" field syntax is augmented to allow
email address in the "For" field. <angle-addr> is augmented to UTF-8 email address in the "For" field. <angle-addr> is augmented to
include UTF-8 email address. In order to allow UTF-8 email addresses include UTF-8 email address. In order to allow UTF-8 email addresses
in an <addr-spec>, <uAddr-Spec> is added to <item-value>. in an <addr-spec>, <uAddr-Spec> is added to <item-value>.
item-value =/ uAddr-Spec item-value =/ uAddr-Spec
4.6. message/global 4.6. message/global
Internationalized messages must only be transmitted as authorized by Internationalized messages MUST only be transmitted as authorized by
[I-D.yao-eai-rfc5336bis] or within a non-SMTP environment which [I-D.ietf-eai-rfc5336bis] or within a non-SMTP environment which
supports these messages. A message is a "message/global message", if supports these messages. A message is a "message/global message", if
o it contains UTF-8 header values as specified in this document, or o it contains UTF-8 header values as specified in this document, or
o it contains UTF-8 values in the headers fields of body parts. o it contains UTF-8 values in the headers fields of body parts.
The type message/global is similar to message/rfc822, except that it The type message/global is similar to message/rfc822, except that it
contains a message that can contain UTF-8 characters in the headers specifies that a message can contain UTF-8 characters in the headers
of the message or body parts. If this type is sent to a 7-bit-only of the message or body parts. If this type is sent to a 7-bit-only
system, it has to be encoded in MIME [RFC2045]. (Note that a system system, it has to be encoded in MIME [RFC2045]. (Note that a system
compliant with MIME that doesn't recognize message/global would treat compliant with MIME that doesn't recognize message/global MUST treat
it as "application/octet-stream" as described in Section 5.2.4 of it as "application/octet-stream" as described in Section 5.2.4 of
[RFC2046].) [RFC2046].)
Type name: message Type name: message
Subtype name: global Subtype name: global
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
skipping to change at page 10, line 12 skipping to change at page 10, line 30
Security considerations: See Section 5. Security considerations: See Section 5.
Interoperability considerations: The media type provides Interoperability considerations: The media type provides
functionality similar to the message/rfc822 content type for email functionality similar to the message/rfc822 content type for email
messages with international email headers. When there is a need messages with international email headers. When there is a need
to embed or return such content in another message, there is to embed or return such content in another message, there is
generally an option to use this media type and leave the content generally an option to use this media type and leave the content
unchanged or down-convert the content to message/rfc822. Both of unchanged or down-convert the content to message/rfc822. Both of
these choices will interoperate with the installed base, but with these choices will interoperate with the installed base, but with
different properties. Systems unaware of international headers different properties. Systems unaware of internationalized
will typically treat a message/global body part as an unknown headers will typically treat a message/global body part as an
attachment, while they will understand the structure of a message/ unknown attachment, while they will understand the structure of a
rfc822. However, systems that understand message/global will message/rfc822. However, systems that understand message/global
provide functionality superior to the result of a down-conversion will provide functionality superior to the result of a down-
to message/rfc822. The most interoperable choice depends on the conversion to message/rfc822. The most interoperable choice
deployed software. depends on the deployed software.
Published specification: RFC XXXX Published specification: RFC XXXX
Applications that use this media type: SMTP servers and email Applications that use this media type: SMTP servers and email
clients that support multipart/report generation or parsing. clients that support multipart/report generation or parsing.
Email clients which forward messages with international headers as Email clients which forward messages with international headers as
attachments. attachments.
Additional information: Additional information:
skipping to change at page 12, line 37 skipping to change at page 13, line 9
5. Upgrade some references from I-Ds to RFC. 5. Upgrade some references from I-Ds to RFC.
8.2. draft-ietf-eai-rfc5335bis-01 8.2. draft-ietf-eai-rfc5335bis-01
1. Author name revised. 1. Author name revised.
8.3. draft-ietf-eai-rfc5335bis-02 8.3. draft-ietf-eai-rfc5335bis-02
1. ABNF revised. 1. ABNF revised.
8.4. draft-ietf-eai-rfc5335bis-03
1. Fix typos
2. ABNF revised
3. Improve sentence
9. References 9. References
9.1. Normative References 9.1. Normative References
[I-D.ietf-eai-frmwrk-4952bis] Klensin, J. and Y. Ko, "Overview and [I-D.ietf-eai-frmwrk-4952bis] Klensin, J. and Y. Ko, "Overview and
Framework for Internationalized Framework for Internationalized
Email", Email",
draft-ietf-eai-frmwrk-4952bis-02 (work draft-ietf-eai-frmwrk-4952bis-10 (work
in progress), July 2010. in progress), September 2010.
[I-D.yao-eai-rfc5336bis] Yao, J. and W. MAO, "SMTP Extension [I-D.ietf-eai-rfc5336bis] Yao, J. and W. MAO, "SMTP Extension
for Internationalized Email Address", for Internationalized Email Address",
draft-yao-eai-rfc5336bis-01 (work in draft-ietf-eai-rfc5336bis-04 (work in
progress), July 2009. progress), October 2010.
[RFC1652] Klensin, J., Freed, N., Rose, M., [RFC1652] Klensin, J., Freed, N., Rose, M.,
Stefferud, E., and D. Crocker, "SMTP Stefferud, E., and D. Crocker, "SMTP
Service Extension for 8bit- Service Extension for 8bit-
MIMEtransport", RFC 1652, July 1994. MIMEtransport", RFC 1652, July 1994.
[RFC2119] Bradner, S., "Key words for use in [RFC2119] Bradner, S., "Key words for use in
RFCs to Indicate Requirement Levels", RFCs to Indicate Requirement Levels",
BCP 14, RFC 2119, March 1997. BCP 14, RFC 2119, March 1997.
skipping to change at page 13, line 48 skipping to change at page 14, line 29
[RFC2046] Freed, N. and N. Borenstein, [RFC2046] Freed, N. and N. Borenstein,
"Multipurpose Internet Mail Extensions "Multipurpose Internet Mail Extensions
(MIME) Part Two: Media Types", (MIME) Part Two: Media Types",
RFC 2046, November 1996. RFC 2046, November 1996.
[RFC2047] Moore, K., "MIME (Multipurpose [RFC2047] Moore, K., "MIME (Multipurpose
Internet Mail Extensions) Part Three: Internet Mail Extensions) Part Three:
Message Header Extensions for Non- Message Header Extensions for Non-
ASCII Text", RFC 2047, November 1996. ASCII Text", RFC 2047, November 1996.
[RFC5504] Fujiwara, K. and Y. Yoneya,
"Downgrading Mechanism for Email
Address Internationalization",
RFC 5504, March 2009.
[RFC5721] Gellens, R. and C. Newman, "POP3
Support for UTF-8", RFC 5721,
February 2010.
[RFC5738] Resnick, P. and C. Newman, "IMAP
Support for UTF-8", RFC 5738,
March 2010.
Authors' Addresses Authors' Addresses
Abel YANG Abel Yang
TWNIC TWNIC
4F-2, No. 9, Sec 2, Roosvelt Rd. 4F-2, No. 9, Sec 2, Roosevelt Rd.
Taipei, 100 Taipei, 100
Taiwan Taiwan
Phone: +886 2 23411313 ext 505 Phone: +886 2 23411313 ext 505
EMail: abelyang@twnic.net.tw EMail: abelyang@twnic.net.tw
Shawn Steele Shawn Steele
Microsoft Microsoft
EMail: Shawn.Steele@microsoft.com EMail: Shawn.Steele@microsoft.com
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