Network Working Group J. Yao, Ed.
Internet-Draft W. Mao, Ed.
Expires: August 16, 2007 CNNIC
February 12, 2007
SMTP extension for internationalized email address
draft-ietf-eai-smtpext-03.txt
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
Internationalized email address includes two parts, the local part
and the domain part. The ways email addresses are used by protocols
are different from the ways domain names are used. The most critical
difference is that emails are delivered through a chain of peering
clients and servers while domain names are resolved by name servers
by looking up their own tables. In addition to this, email transport
protocols SMTP and ESMTP provide a negotiation mechanism through
which clients can make decisions for further processing. This
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document specifies the use of SMTP extension for internationalized
email address delivery. It also mentions the backward compatible
mechanism for downgrade procedure, as specified in an associated
specification.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Role of this specification . . . . . . . . . . . . . . . . 3
1.2. Proposal Context . . . . . . . . . . . . . . . . . . . . . 3
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Mail Transport-level Protocol . . . . . . . . . . . . . . . . 4
2.1. Framework for the Internationalization Extension . . . . . 4
2.2. The Address Internationalization Service Extension . . . . 5
2.3. Extended Mailbox Address Syntax . . . . . . . . . . . . . 5
2.4. The ALT-ADDRESS parameter . . . . . . . . . . . . . . . . 8
2.5. The Suggestion of the Value of the ALT-ADDRESS
parameter . . . . . . . . . . . . . . . . . . . . . . . . 9
2.6. Body Parts and SMTP Extensions . . . . . . . . . . . . . . 9
2.7. Additional ESMTP Changes and Clarifications . . . . . . . 10
2.7.1. The Initial SMTP Exchange . . . . . . . . . . . . . . 10
2.7.2. Message Retry . . . . . . . . . . . . . . . . . . . . 10
2.7.3. Trace Information . . . . . . . . . . . . . . . . . . 11
2.7.4. Mailing List Question . . . . . . . . . . . . . . . . 12
2.7.5. Message Header Label . . . . . . . . . . . . . . . . . 12
2.7.6. POP and IMAP . . . . . . . . . . . . . . . . . . . . . 12
2.7.7. SMTP Service Extension for DSNs . . . . . . . . . . . 13
3. Potential problems . . . . . . . . . . . . . . . . . . . . . . 13
3.1. Impact to IRI . . . . . . . . . . . . . . . . . . . . . . 13
3.2. Impact to RFC 2476 and many email related RFC . . . . . . 13
4. Implementation Advice . . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
6. Security considerations . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
8. Change History . . . . . . . . . . . . . . . . . . . . . . . . 14
8.1. draft-ietf-eai-smtpext: Version 00 . . . . . . . . . . . . 14
8.2. draft-ietf-eai-smtpext: Version 01 . . . . . . . . . . . . 14
8.3. draft-ietf-eai-smtpext: Version 02 . . . . . . . . . . . . 15
8.4. draft-ietf-eai-smtpext: Version 03 . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . . . 19
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1. Introduction
Internationalized email address is different from the
internationalized domain name (IDN). It can be solved by exploiting
the negotiation mechanism while IDN can not use the negotiation
mechanism. So internationalized email address SHOULD be solved in
the mail transport-level using the negotiation mechanism, which is an
architecturally desirable approach. This document specifies a
protocol to solve the problem of internationalized email address
based on ESMTP. The protocol proposed here is MTA-level solution
which is feasible, architecturally elegant, and not as difficult to
be deployed in relevant communities.
1.1. Role of this specification
An overview document [EAI-overview] specifies the requirements for,
and components of, full internationalization of electronic mail.
This document specifies an element of that work, specifically the
definition of an SMTP extension [RFC1869] for the internationalized
email address transport delivery.
1.2. Proposal Context
In order to use internationalized email addresses, we need to
internationalize both the domain part and the local part of the email
address. The domain part of the email address has been
internationalized through IDNA RFC 3490 [RFC3490]. But the local
part of the email address still remains as non-internationalized.
The syntax of Internet email addresses is restricted to a subset of
7-bit ASCII for the domain-part, with a less-restricted subset for
the local-part. These restrictions are specified in RFC 2821
[RFC2821]. To be able to deliver internationalized email through
SMTP servers, we need to upgrade SMTP server to be able to carry the
internationalized email address. Since the older SMTP servers, the
mail-reading clients and other systems that are downstream from them
might not be prepared to handle these extended addresses, an SMTP
extension is specified to identify and protect the addressing
mechanism.
This specification describes a change to the email transport
mechanism that permits non-ASCII address in both the envelope and
header fields of messages. The context for the change is described
in [EAI-overview] and the details of the header changes are described
in [EAI-utf8header].
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1.3. Terminology
The key words "MUST", "SHALL", "REQUIRED", "SHOULD", "RECOMMENDED",
and "MAY" in this document are to be interpreted as described in RFC
2119 [RFC2119].
All specialized terms used in this specification are defined in the
EAI overview [EAI-overview] or in [RFC2821] and [RFC2822]. The terms
"ASCII address", "internationalized email address", "non-ASCII
address", "i18mail address", "UTF8SMTP", "message" and "mailing list"
are used with the definitions from the EAI overview document.
This document defines only those syntax rules that are different from
those of the base email specifications [RFC2821][RFC2822] and, where
the earlier rules are upgraded or extended, gives them new names.
When the new rule is a small upgrade to the older one, it is
typically given a name starting with "u". Rules that are undefined
here may be found in the base email documents under the same names.
This document is being discussed on the EAI mailing list. See
https://www1.ietf.org/mailman/listinfo/ima for information about
subscribing. The list's archive is at
http://www1.ietf.org/mail-archive/web/ima/index.html.
2. Mail Transport-level Protocol
2.1. Framework for the Internationalization Extension
The following service extension is defined:
1. The name of the SMTP service extension is "Email Address
Internationalization";
2. The EHLO keyword value associated with this extension is
"UTF8SMTP";
3. No parameter values are defined for this EHLO keyword value. In
order to permit future (although unanticipated) extensions, the
EHLO response MUST NOT contain any parameters for that keyword.
If a parameter appears, the SMTP client that is conformant to
this version of this specification MUST treat the ESMTP response
as if the "UTF8SMTP" keyword did not appear.
4. An optional parameter is added to the SMTP MAIL and RCPT
commands. The parameter is named as ALT-ADDRESS. The "ALT-
ADDRESS" requires an all-ASCII address as a substitute for the
i18mail addresses that we call the primary address; you can learn
more in [EAI-overview] or [EAI-downgrading]. The value of "ALT-
ADDRESS" is set by the sender when MUA and the Submission server
have a communication.
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5. No additional SMTP verbs are defined by this extension.
6. Servers offering this extension MUST provide support for, and
announce, the 8BITMIME extension [RFC1652].
2.2. The Address Internationalization Service Extension
An SMTP Server that announces this extension MUST be prepared to
accept a UTF-8 string [RFC3629] in any position in which RFC 2821
specifies that a "mailbox" MAY appear. That string MUST be parsed
only as specified in RFC 2821, i.e., by separating the mailbox into
source route, local part and domain part, using only the characters
colon (U+003A), comma (U+002C), and at-sign (U+0040) as specified
there. Once isolated by this parsing process, the local part MUST be
treated as opaque unless the SMTP Server is the final delivery MTA.
Any domain names that are to be looked up in the DNS MUST first be
processed into the form as specified in IDNA [RFC3490] by means of
the ToASCII() operation unless they are already in that form. Any
domain names that are to be compared to local strings SHOULD be
checked for validity and then MUST be compared as specified in
section 3.4 of IDNA.
An SMTP Client that receives the UTF8SMTP extension keyword in
response to the "EHLO" command MAY transmit a mailbox name as an
internationalized string in UTF-8 form and MAY send an
internationalized mail header [EAI-utf8header]. It MAY transmit the
domain part of that string in either punycode (derived from the IDNA
process) or UTF-8 form. If it sends the domain in UTF-8 form, the
original SMTP client SHOULD first verify that the string is valid for
a domain name according to IDNA rules. As required by RFC 2821, it
MUST not attempt to parse, evaluate, or transform the local part in
any way if the UTF8SMTP SMTP extension is offered by the server. If
the UTF8SMTP SMTP extension is not offered by the Server, the SMTP
Client MUST NOT transmit an internationalized address and MUST NOT
transmit a mail body which contains internationalized mail headers
[EAI-utf8header]. Instead, it MUST either return the message to the
user as undeliverable or replace it with the alternate ASCII address.
If it is replaced, the replacement MUST be the ASCII-only address
specified with the ALT-ADDRESS parameter.[EAI-downgrading].
2.3. Extended Mailbox Address Syntax
RFC 2821, section 4.1.2, defines the syntax of a mailbox entirely in
terms of ASCII characters, using the production for "Mailbox" and
those on which it depends.
The key changes made by this specification are, informally, to
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o Change the definition of "sub-domain" to permit either the
definition above or a UTF-8 string representing a DNS label that
is conformant with IDNA [RFC3490]. That label MUST NOT contain
the characters "@" or ".", even though those characters can
normally be inserted into a DNS label.
o Change the definition of "Atom" to permit either the definition
above or a UTF-8 string. That string MUST NOT contain any of the
ASCII characters (either graphics or controls) that are not
permitted in "atext"; it is otherwise unrestricted.
According to the description above, define the syntax of an
internationalized email mailbox with ABNF [RFC4234] as
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uMailbox = uLocal-part "@" uDomain
; Replace Mailbox in RFC 2821, section 4.1.2
uLocal-part = uDot-string / uQuoted-string
; MAY be case-sensitive
; Replace Local-part in RFC 2821, section 4.1.2
uDot-string = uAtom *("." uAtom)
; Replace Dot-string in RFC 2821, section 4.1.2
uAtom = 1*ucharacter
; Replace Atom in RFC 2821, section 4.1.2
ucharacter = atext / Non-ASCII
; Replace character in RFC 2821, section 4.1.2
; atext is defined in RFC 2822
; UTF8-2, UTF8-3 and UTF8-4 are defined in RFC 3629
uQuoted-string = DQUOTE *uqcontent DQUOTE
; Replace Quoted-string in RFC 2821, section 4.1.2
; DQUOTE is Double Quote defined in RFC 4234
uqcontent = qcontent / Non-ASCII
; qcontent is defined in RFC 2822, section 3.2.5
uDomain = (sub-udomain 1*("." sub-udomain)) / address-literal
; Replace Domain in RFC 2821, section 4.1.2
; address-literal is defined in RFC2821 section 4.1.2
sub-udomain = uLet-dig [uLdh-str]
; Replace sub-domain in RFC 2821, section 4.1.2
uLet-dig = Let-dig / Non-ASCII
; Let-dig in the right of '=' is defined in RFC 2822
uLdh-str = *( ALPHA / DIGIT / "-" / Non-ASCII) uLet-dig
; Replace Ldh-str in RFC 2821, section 4.1.2
Non-ASCII = UTF8-2 / UTF8-3 / UTF8-4
The value of "udomain" SHOULD be verified with [RFC3490]; If failed,
the email address with that udomain can not be regarded as the valid
email address.
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2.4. The ALT-ADDRESS parameter
If the UTF8SMTP extension is offered, the syntax of the SMTP MAIL and
RCPT commands is extended to support the optional esmtp-keyword "ALT-
ADDRESS", to specify the conditions under which the SMTP server may
use ALT-ADDRESS for the possible downgrading. If the ALT-ADDRESS
esmtp-keyword is used, it MUST have an associated esmtp-value (ALT-
ADDRESS-esmtp-value which is defined below) which requires an all-
ASCII email address.
Based on the definition of mail-parameters in [RFC2821], the ALT-
ADDRESS parameter usage in the commands of "mail from" and "rcpt to"
is defined below.
"MAIL FROM:" SP <uReverse-path> [ SP <mail-parameters> ]<CRLF>
; Update mail command in RFC 2821, section 3.3
"RCPT TO:" SP <uForward-path> [ SP <rcpt-parameters> ]<CRLF>
; Update rcpt command in RFC 2821, section 3.3
uReverse-path = uPath
; Replace Reverse-path in RFC 2821, section 4.1.2
uForward-path = uPath
; Replace Forward-path in RFC 2821, section 4.1.2
uPath = "<" [ uA-d-l ":" ] uMailbox ">"
; Replace Path in RFC 2821, section 4.1.2
uA-d-l = uAt-domain *( "," uA-d-l )
; Replace A-d-l in RFC 2821, section 4.1.2
uAt-domain = "@" udomain
; Replace At-domain in RFC 2821, section 4.1.2
; udomain is defined in section 2.3 of this document
ALT-ADDRESS-esmtp-value=Mailbox
; Mailbox is defined in RFC 2821, section 4.1.2
The use of the ALT-ADDRESS is specified below: If some involved SMTP
servers can not support UTF8SMTP capability and if the sender has
already set the ALT-ADDRESS value, the client SMTP server will use
this address as the email address when the SMTP server does the
subsequent operations. If the ALT-ADDRESS value is not set by the
sender, the email must be bounced to the original sender. If the
email is bounced due to the incapability of supporting UTF8SMTP, the
relative server should issue the response error code "5.3.3" defined
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in [RFC3463] which means that System is not capable of selected
features, permanent failure.
2.5. The Suggestion of the Value of the ALT-ADDRESS parameter
The "ALT-ADDRESS" requires an all-ASCII address. There are two
alternative ways to set ALT-ADDRESS value: one is set by the sender
using the all-ASCII address, the other is set using the transformed
email address.
Some may prefer transforming the non-ASCII address to the ASCII
Compatible Encoding(ACE) address as the value of the ALT-ADDRESS. A
significant obstacle with applying an ACE to all local-parts is that
the sending or converting system doesn't know if there are some
specific data or instructions embedded in the address that the ACE
process would hide. Some SMTP servers may depend on these specific
data or instructions to do some operations while the local parts
applied with ACE will lose or hide these data or instructions. SMTP
[RFC2821] prohibits SMTP relays from converting local parts because
the level of SMTP relays' knowledge on the structure of local parts
is assumed to be zero. However, we can raise the knowledge level by
supplying additional information. Many human users' email addresses
do not have any embedded structure processed by the final delivery
MTA. In that case, the sender can specify that these email addresses
are safe to be converted in the predefined way. The final delivery
SMTP server can revert the addresses even though they are as in all
ASCII form. Unless the MUA or the submission server clearly knows
that the non-ASCII address can be safely transformed into the all-
ASCII address, the non-ASCII address should not be transformed
because transformed email address may cause some potential problems.
This document suggests that the ALT-ADDRESS is set directly by the
sender; In default, the all-ASCII address should not be gotten from
the transformation of the non-ASCII address.
2.6. Body Parts and SMTP Extensions
While this specification requires that servers support the 8BITMIME
extension [RFC1652] to ensure that servers have adequate handling
capability for 8-bit data and to avoid a number of complex encoding
problems, the use of internationalized addresses obviously does not
require non-ASCII body parts in the MIME message. The UTF8SMTP
extension MAY be used with the BODY=8BITMIME parameter if that is
appropriate given the body content or, if the server advertises it
and it is appropriate, with the BODY=BINARYMIME parameter specified
in [RFC3030].
Assuming that the server advertises UTF8SMTP and 8BITMIME, and at
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least one non-ASCII address, with or without ALT-ADDRESS, the precise
interpretation of these parameters on the MAIL command is:
1. Headers are in UTF-8, body parts are in ASCII.
2. Headers are in UTF-8, some or all body parts contain 8-bit line-
oriented data.
3. Headers are in UTF-8, some or all body parts contain binary data
without restriction as to line lengths or delimiters.
2.7. Additional ESMTP Changes and Clarifications
The mail transport process involves addresses ("mailboxes") and
domain names in contexts in addition to the MAIL and RCPT commands
and extended alternatives to them. In general, the rule is that,
when RFC 2821 specifies a mailbox, this document expects UTF-8 to be
used for the entire string; when RFC 2821 specifies a domain name,
the name SHOULD be in punycode form if its raw form is non-ASCII.
The following subsections list and discuss all of the relevant cases.
Support and use of this extension requires support for 8BITMIME. It
means that 8BITMIME MUST be advertised by the UTF8SMTP capability
SMTP server.
2.7.1. The Initial SMTP Exchange
When an SMTP or ESMTP connection is opened, the server sends a
"banner" response consisting of the 220 reply code and some
information. The client then sends the EHLO command. Since the
client cannot know whether the server supports UTF8SMTP until after
it receives the response from EHLO, any domain names that appear in
this dialogue, or in responses to EHLO, MUST be in hostname form,
i.e., internationalized ones MUST be in punycode form.
2.7.2. Message Retry
When an MSA or MTA encounters a server that doesn't support UTF8SMTP
while relaying a message that requires such support, it is
RECOMMENDED that an alternate MX be tried, and/or the message is
requeued for a later attempt, rather than immediately downgrading or
bouncing. If the message is requeued, the total elapsed time before
bouncing or downgrading SHOULD be smaller than the value used for
other SMTP error conditions such as host unreachable or persistent
4xx response codes.
This alternate-MX-or-retry-later technique SHOULD NOT be used when
the message's return path is a non-ASCII address and the specific
forward path being attempted is an ASCII address (because the
implication that the delivery path normally supports UTF8SMTP does
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not hold in this case).
The selection of submission servers is presumably under the control
of the sender's client, while the selection of potential intermediate
relays is under the control of the administration of the final
delivery server. Hence, there is a presumption, at least when the
recipient address is non-ASCII, that the delivery path servers
normally support UTF8SMTP (if the sender's client or MSA didn't
support UTF8SMTP, the message would not have been accepted for
delivery in the first place). Thus, a lack of UTF8SMTP support is
likely to be a temporary situation, such as a normal inbound server
being down and a cooperating site acting as a backup MX. If the lack
of UTF8SMTP in the delivery path of a message is a temporary
situation, and the message is sent successfully after retrying, then
it was a good thing to do. Of course, if there is always an ASCII-
only SMTP server in the path, then retrying only adds delay to the
failure (bounce or downgrade).
2.7.3. Trace Information
When an SMTP server receives a message for delivery or further
processing, it MUST insert trace ("time stamp" or "Received")
information at the beginning of the message content. The most
important use of Received: lines is for debugging mail faults. For
the trace information, we update the time stamp line and the return
path line [RFC2821] formally defined as follows:
uReturn-path-line = "Return-Path:" FWS uReverse-path <CRLF>
; Replaces Return-path-line in the section 4.4 of [RFC2821]
; uReverse-path is defined in Section 2.3
uTime-stamp-line = "Received:" FWS uStamp <CRLF>
; Replaces Time-stamp-line in the section 4.4 of [RFC2821]
uStamp = From-domain By-domain uOpt-info ";" FWS date-time
; Replaces Stamp in the section 4.4 of [RFC2821]
uOpt-info = [Via] [With] [ID] [uFor]
; Replaces Opt-info in the section 4.4 of [RFC2821]
; [With]'s protocl value will allow UTF8SMTP value
uFor = "FOR" FWS 1*( Path / uMailbox ) CFWS
; Replaces For in the section 4.4 of [RFC2821]
; uReverse-path is defined in Section 2.4
Except in the 'uFor' and 'uReverse-path' line where non-ASCII domain
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name may be used, internationalized domain names in Received fields
MUST be transmitted in the punycode form. The [With]'s protocl value
will have the value of 'UTF8SMTP' for UTF8SMTP extension. We will
give more informaiton about this in "IANA consideration" section of
this document. If a "for" clause containing non-ASCII is encountered
when downgrading a message, it is better to just drop the "for"
clause rather than figure out some creative way to encode it. When
only the domain portion of a "for" clause address contains non-ASCII,
this document suggests using the punycode form of the domain portion.
For more detailed information, you may see it in [EAI-utf8header].
2.7.4. Mailing List Question
How a mixture of traditional and internationalized addresses on a
mailing list will impact message flows, error reports, and delivery
notifications in all plausible combinations of UTF8SMTP capability
and un-capability servers is discussed and specified in the
[EAI-mailing list].
2.7.5. Message Header Label
Today it is routine that many MTAs scan every message for spam, virus
or other reasons. It seems that few MTAs depend on "Header-Type"
fields or marker to decide the message's type. The better choice is
to rely on scanning the message to decide the message's type:
UTF8SMTP or ASCII, instead of the header label "Header-Type" fields
or marker. The message header label "Header-Type" SHOULD NOT be used
to identify and distinguish the i18mail message from the normal
message when SMTP messages are transmitted on wire. This issue is
discussed and specified in [EAI-utf8header].
2.7.6. POP and IMAP
While SMTP mainly takes care of the transportation of messages and
the header fields on wire, POP essentially handles the retrieval of
mail objects from the server by a client. In order to use
internationalized user names based on i18mail for the retrieval of
messages from a mail server using the POP protocol, a new capability
SHOULD be introduced following the POP3 extension mechanism
[RFC2449]. This is discussed and specified in the [EAI-pop].
IMAP [RFC3501] uses the traditional user name which is based on
ASCII. IMAP SHOULD be updated to support the internationalized user
names based on i18mail for the retrieval of messages from a mail
server. This is discussed and specified in the [EAI-imap].
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2.7.7. SMTP Service Extension for DSNs
The existing draft standard Delivery status notifications
(DSNs)[RFC3461] is presently limited to US-ASCII text in the machine
readable portions of the protocol. "International Delivery and
Disposition Notifications" [EAI-dsn] adds a new address type for
international email addresses so an original recipient address with
non-US-ASCII characters can be correctly preserved even after
downgrading. If an SMTP server advertises both the UTF8SMTP and the
DSN extension, that server MUST implement EAI-dsn [EAI-dsn] including
support for the ORCPT parameter.
3. Potential problems
3.1. Impact to IRI
The mailto: schema in IRI [RFC3987] MAY need to be modified when EAI
is standardized.
3.2. Impact to RFC 2476 and many email related RFC
The EAI protocols will impact on many email related RFC documents
such as Message Submission [RFC2476]. These protocols SHOULD be
considered when implementing the EAI protocol.
4. Implementation Advice
In the absence of this extension, SMTP clients and servers are
constrained to using only those addresses permitted by RFC 2821. The
local parts of those addresses MAY be made up of any ASCII
characters, although some of them MUST be quoted as specified there.
It is notable in an internationalization context that there is a long
history on some systems of using overstruck ASCII characters (a
character, a backspace, and another character) within a quoted string
to approximate non-ASCII characters. This form of
internationalization SHOULD be phased out as this extension becomes
widely deployed but backward-compatibility considerations require
that it continue to be supported.
5. IANA Considerations
IANA is requested to add "UTF8SMTP" to the SMTP extensions registry
with the entry pointing to this specification for its definition.
The "Mail Transmission Types" registry is requested to be updated to
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include the following new entries:
WITH protocol types Description Reference
------------------- ---------------------------- ---------
UTF8SMTP UTF8SMTP with Service Extensions [RFCxxxx]
UTF8SMTPA UTF8SMTP with SMTP AUTH [RFCxxxx]
UTF8SMTPS UTF8SMTP with STARTTLS [RFCxxxx]
UTF8SMTPSA UTF8SMTP with both STARTTLS and [RFCxxxx]
SMTP AUTH
6. Security considerations
See the extended security considerations discussion in [EAI-overview]
7. Acknowledgements
Much of the text in the initial version of this document was derived
or copied from [Klensin-emailaddr] with the permission of the author.
Significant comments and suggestions were received from Xiaodong LEE,
Nai-Wen Hsu, Yangwoo KO, Yoshiro YONEYA, and other members of the JET
team and were incorporated into the document. Special thanks to
those contributors for this version of document, those includes (but
not limited to) John C Klensin, Charles Lindsey, Dave Crocker, Harald
Tveit Alvestrand, Marcos Sanz, Chris Newman, Martin Duerst, Edmon
Chung, Tony Finch, Kari Hurtta, Randall Gellens.
8. Change History
[[anchor21: REMOVE THIS: This section is used for tracking the update
of this document. It may be useful to retain parts of it to
facilitate establishing dates and documents for the history of this
work.]]
8.1. draft-ietf-eai-smtpext: Version 00
This version supercedes draft-yao-ima-smtpext-03.txt. It refines the
ABNF definiton of the internationalized email address. It represents
as the EAI working group document.
8.2. draft-ietf-eai-smtpext: Version 01
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Internet-Draft EAI February 2007
o Upgraded to reflect discussions during IETF 66.
o Remove the atomic parameter.
o Add the new section of "the Suggestion of the value of the ALT-
ADDRESS parameter".
8.3. draft-ietf-eai-smtpext: Version 02
o Upgraded to reflect the recent discussion of the ima@ietf.org
mailing list.
o Add the section of "Body Parts and SMTP Extensions".
o Add the new section of "Change History".
o Add the subsection about SMTP extensions for DSN.
8.4. draft-ietf-eai-smtpext: Version 03
o Update the syntax related to mailbox.
o Update the trace field section.
o Add the new section about message retry.
o Update the subsection about SMTP extensions for DSN.
9. References
9.1. Normative References
[ASCII] Cerf, V., "ASCII format for network interchange", RFC 20,
October 1969.
[EAI-downgrading]
YONEYA, Y., Ed. and K. Fujiwara, Ed., "Downgrading
mechanism for Internationalized eMail Address (IMA)",
draft-ietf-eai-downgrade-02 (work in progress),
August 2006.
[EAI-dsn] Newman, C., "SMTP extensions for DSNs",
draft-ietf-eai-dsn-00.txt (work in progress), 1 2007.
[EAI-imap]
Resnick, P. and C. Newman, "Considerations for IMAP in
Conjunction with Email Address Internationalization",
draft-ietf-eai-imap-utf8-00 (work in progress), May 2006.
[EAI-mailing list]
Gellens, R. and E. Chung, "Mailing Lists and
Internationalized Email Addresses",
draft-ietf-eai-mailinglist-01.txt (work in progress),
January 2007.
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Internet-Draft EAI February 2007
[EAI-overview]
Klensin, J. and Y. Ko, "Overview and Framework for
Internationalized Email", draft-ietf-eai-framework-04.txt
(work in progress), 12 2006.
[EAI-pop] Newman, C., "POP3 Support for UTF-8",
draft-ietf-eai-pop-01.txt (work in progress),
January 2007.
[]
Yeh, J., "Transmission of Email Headers in UTF-8
Encoding", draft-ietf-eai-utf8headers-01.txt (work in
progress), August 2006.
[RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extension for 8bit-MIMEtransport",
RFC 1652, July 1994.
[RFC1869] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extensions", STD 10, RFC 1869,
November 1995.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2449] Gellens, R., Newman, C., and L. Lundblade, "POP3 Extension
Mechanism", RFC 2449, November 1998.
[RFC2476] Gellens, R. and J. Klensin, "Message Submission",
RFC 2476, December 1998.
[RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
April 2001.
[RFC2822] Resnick, P., "Internet Message Format", RFC 2822,
April 2001.
[RFC3030] Vaudreuil, G., "SMTP Service Extensions for Transmission
of Large and Binary MIME Messages", RFC 3030,
December 2000.
[RFC3454] Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ("stringprep")", RFC 3454,
December 2002.
[RFC3461] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service
Extension for Delivery Status Notifications (DSNs)",
RFC 3461, January 2003.
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Internet-Draft EAI February 2007
[RFC3463] Vaudreuil, G., "Enhanced Mail System Status Codes",
RFC 3463, January 2003.
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003.
[RFC3492] Costello, A., "Punycode: A Bootstring encoding of Unicode
for Internationalized Domain Names in Applications
(IDNA)", RFC 3492, March 2003.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", RFC 3629, November 2003.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, January 2005.
[RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.
9.2. Informative References
[Klensin-emailaddr]
Klensin, J., "Internationalization of Email Addresses",
draft-klensin-emailaddr-i18n-03 (work in progress),
July 2005.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
Authors' Addresses
Jiankang YAO (editor)
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing
Phone: +86 10 58813007
Email: yaojk@cnnic.cn
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Internet-Draft EAI February 2007
Wei MAO (editor)
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing
Phone: +86 10 58813055
Email: mao@cnnic.cn
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