Network Working Group J. Yao
Internet-Draft W. Mao
Obsoletes: RFC5336 CNNIC
(if approved) December 2, 2010
Updates: RFC5321 and 5322
(if approved)
Intended status: Standards Track
Expires: June 5, 2011
SMTP Extension for Internationalized Email Address
draft-ietf-eai-rfc5336bis-05.txt
Abstract
This document specifies an SMTP extension for transport and delivery
of email messages with internationalized email addresses or header
information. This document updates some syntax rules defined in RFC
5321 and RFC 5322.
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
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This Internet-Draft will expire on June 5, 2011.
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include Simplified BSD License text as described in Section 4.e of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Role of This Specification . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview of Operation . . . . . . . . . . . . . . . . . . . . 5
3. Mail Transport-Level Protocol . . . . . . . . . . . . . . . . 5
3.1. Framework for the Internationalization Extension . . . . . 5
3.2. The UTF8SMTPbis Extension . . . . . . . . . . . . . . . . 5
3.3. Extended Mailbox Address Syntax . . . . . . . . . . . . . 7
3.4. UTF8 addresses and Response Codes . . . . . . . . . . . . 9
3.5. Body Parts and SMTP Extensions . . . . . . . . . . . . . . 9
3.6. Additional ESMTP Changes and Clarifications . . . . . . . 10
3.6.1. The Initial SMTP Exchange . . . . . . . . . . . . . . 10
3.6.2. Mail eXchangers . . . . . . . . . . . . . . . . . . . 10
3.6.3. Trace Information . . . . . . . . . . . . . . . . . . 11
3.6.4. UTF-8 Strings in Replies . . . . . . . . . . . . . . . 12
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
7. Change History . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. draft-yao-eai-rfc5336bis: Version 00 . . . . . . . . . . . 16
7.2. draft-ietf-eai-rfc5336bis: Version 00 . . . . . . . . . . 16
7.3. draft-ietf-eai-rfc5336bis: Version 01 . . . . . . . . . . 16
7.4. draft-ietf-eai-rfc5336bis: Version 02 . . . . . . . . . . 16
7.5. draft-ietf-eai-rfc5336bis: Version 03 . . . . . . . . . . 16
7.6. draft-ietf-eai-rfc5336bis: Version 04 . . . . . . . . . . 16
7.7. draft-ietf-eai-rfc5336bis: Version 05 . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative References . . . . . . . . . . . . . . . . . . . 17
8.2. Informative References . . . . . . . . . . . . . . . . . . 18
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
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1. Introduction
The Simple Mail Transfer Protocol [RFC5321] provides a negotiation
mechanism about service extension with which clients can discover
server capabilities and make decisions for further processing. This
document use this mechanism to support an internationalized email
address. An extended overview of the extension model for
internationalized addresses and headers appears in [RFC4952bis],
referred to as "the framework document" or just as "framework"
elsewhere in this specification. This document specifies an SMTP
extension to permit internationalized email addresses in envelopes,
and UNICODE characters (encoded in UTF-8) [RFC3629] in headers.
1.1. Role of This Specification
The framework document specifies the requirements for, and describes
components of, full internationalization of the electronic mail. A
thorough understanding of the information in that document and in the
base Internet email specifications [RFC5321] [RFC5322] is necessary
to understand and implement this specification.
This document specifies an element of the email internationalization
work, specifically the definition of an SMTP extension for
internationalized email address transport delivery.
1.2. Terminology
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].
The terms "UTF-8 string" or "UTF-8 character" are used informally to
refer to Unicode characters encoded in UTF-8. All other specialized
terms used in this specification are defined in the framework
document or in the base Internet email specifications. In
particular, the terms "ASCII address", "internationalized email
address", "non-ASCII address", "i18mail address",
"UTF8SMTPbis","conventional message", "internationalized message",
"message", and "mailing list" are used in this document according to
the definitions in the framework document.
This specification defines only those Augmented BNF (ABNF) [RFC5234]
syntax rules that are different from those of the base email
specifications and, where the earlier rules are upgraded or extended,
gives them new names. When the new rule is a small modification 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 specifications
under the same names.
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2. Overview of Operation
This specification describes an optional extension to the email
transport mechanism that permits non-ASCII [ASCII] characters in both
the envelope and header fields of messages, which are encoded with
UTF-8 characters. The extension is identified with the token
"UTF8SMTPbis".
The EAI UTF-8 header specification [RFC5335bis] provides the details
of how and where non-ASCII characters are permitted in the header
fields of messages. The context for this specification is described
in the framework document.
3. Mail Transport-Level Protocol
3.1. 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
"UTF8SMTPbis".
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.
Clients MUST reject any parameters; that is, clients MUST behave
as if the parameters do not appear. If a server includes
UTF8SMTPbis in its EHLO response, it MUST be fully compliant with
this version of this specification.
4. One optional parameter "UTF8REPLY" is added to the VRFY and EXPN
commands. The parameter UTF8REPLY has no value. The parameter
indicates that the SMTP client can accept Unicode characters in
UTF-8 encoding in replies from the VRFY and EXPN commands.
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].
7. The reverse-path and forward-path of the SMTP MAIL and RCPT
commands are extended to allow Unicode characters encoded in
UTF-8 in mailbox names (addresses).
8. The mail message body is extended as specified in [RFC5335bis].
9. The UTF8SMTPbis extension is valid on the submission port
[RFC4409], and can be used with LMTP [RFC2033].
3.2. The UTF8SMTPbis Extension
An SMTP server that announces this extension MUST be prepared to
accept a UTF-8 string [RFC3629] in any position in which RFC 5321
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specifies that a mailbox can appear. That string MUST be parsed only
as specified in [RFC5321], 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 Mail
Transfer Agent (MTA). Any domain names to be looked up in the DNS
MUST allow for [RFC5890] behavior. When doing lookups, the server
MUST either use a Unicode aware DNS library, or transform it to
A-label defined in [RFC5890]. 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 of [RFC5891].
An SMTP client that receives the UTF8SMTPbis extension keyword in
response to the EHLO command MAY transmit mailbox names within SMTP
commands as internationalized strings in UTF-8 form. It MAY send a
UTF-8 header [RFC5335bis] (which may also include mailbox names in
UTF-8). It MAY transmit the domain parts of mailbox names within
SMTP commands or the message header as A-labels or U-labels
[RFC5890]. All labels in domain parts of mailbox names which are IDN
forms of A-labels or U-labels MUST be valid. When a Mail User
Agent(MUA) submits a message to a Message Submission Server
("MSA")[RFC4409], it is the responsibility of the MSA to ensure that
all domain labels are valid. The presence of the UTF8SMTPbis
extension does not change the requirement of RFC 5321 that servers
relaying mail MUST NOT attempt to parse, evaluate, or transform the
local part in any way.
If the UTF8SMTPbis SMTP extension is not offered by the server, the
SMTP client MUST NOT transmit an internationalized address and MUST
NOT transmit a mail message containing internationalized mail headers
as described in [RFC5335bis] at any level within its MIME structure
[RFC2045] and [RFC2047]. (For this paragraph, the internationalized
domain name in the form of A-labels as specified in IDNA definitions
[RFC5890] is not considered to be "internationalized".) Instead, if
an SMTP client (SMTP sender) attempts to transfer an
internationalized message and encounters a server that does not
support the extension, it MUST make one of the following three
choices:
1. If and only if the SMTP client (sender) is a Message Submission
Server ("MSA") [RFC4409], it MAY, consistent with the general
provisions for changes by such servers, rewrite the envelope,
headers, or message material to make them entirely ASCII and
consistent with the provisions of RFC 5321 [RFC5321] and RFC 5322
[RFC5322].
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2. It may either reject the message during the SMTP transaction or
accept the message and then generate and transmit a notification
of non-deliverability. Such notification MUST be done as
specified in RFC 5321 [RFC5321], RFC 3464 [RFC3464], and the EAI
delivery status notification (DSN) specification [RFC5337bis].
3. It may find an alternate route to the destination that permits
UTF8SMTPbis. That route may be discovered by trying alternate
Mail eXchanger (MX) hosts (using preference rules as specified in
RFC 5321) or using other means available to the SMTP-sender.
This document applies only when an UTF8SMTPbis-aware client is trying
to send an internationalized message to an UTF8SMTPbis-aware server.
For all other cases, and for addresses and messages that do not
require an UTF8SMTPbis extension, SMTP clients and servers are
expected to behave exactly as specified in [RFC5321].
A UTF8SMTPbis aware MUA/MSA sending to a legacy SMTP server [RFC5321]
and [RFC5322] MAY convert an ASCII@non-ASCII address into the format
of ASCII@A-label [RFC5890] if the email address is in the format of
ASCII@non-ASCII.
3.3. Extended Mailbox Address Syntax
RFC 5321, Section 4.1.2, defines the syntax of a mailbox entirely in
terms of ASCII characters, using the production for a mailbox and
those productions on which it depends.
The key changes made by this specification are, informally, to
o Change the definition of "Domain" to permit either the definition
above or a UTF-8 string representing a DNS label that is
conformant with IDNA definitions [RFC5890].
o Change the definition of "Local-part" 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, the syntax of an
internationalized email mailbox name (address) is defined in ABNF
[RFC5234] as follows.
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uMailbox = uLocal-part "@" ( uDomain / address-literal )
; Replace Mailbox in RFC 5321, Section 4.1.2
address-literal = <See Section 4.1.2 of RFC 5321>
uLocal-part = uDot-string / uQuoted-string
; MAY be case-sensitive
; Replace Local-part in RFC 5321, Section 4.1.2
uDot-string = uAtom *("." uAtom)
; Replace Dot-string in RFC 5321, Section 4.1.2
uAtom = 1*ucharacter
; Replace Atom in RFC 5321, Section 4.1.2
ucharacter = atext / UTF8-non-ascii
atext = <See Section 3.2.3 of RFC 5322>
uQuoted-string = DQUOTE *uqcontent DQUOTE
; Replace Quoted-string in RFC 5321, Section 4.1.2
DQUOTE = <See appendix B.1 of RFC 5234>
uqcontent = qcontent / UTF8-non-ascii
qcontent = <See Section 3.2.4 of RFC 5322>
uDomain = sub-udomain *("." sub-udomain)
; Replace Domain in RFC 5321, Section 4.1.2
sub-udomain = uLet-dig [uLdh-str]
; Replace sub-domain in RFC 5321, Section 4.1.2
uLet-dig = Let-dig / UTF8-non-ascii
Let-dig = <See Section 4.1.2 of RFC 5321>
uLdh-str = *( ALPHA / DIGIT / "-" / UTF8-non-ascii) uLet-dig
; Replace Ldh-str in RFC 5321, Section 4.1.2
UTF8-non-ascii = UTF8-2 / UTF8-3 / UTF8-4
UTF8-2 = <See Section 4 of RFC 3629>
UTF8-3 = <See Section 4 of RFC 3629>
UTF8-4 = <See Section 4 of RFC 3629>
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The value of "uDomain" SHOULD be verified by IDNA definitions
[RFC5890]. If that verification fails, the email address with that
uDomain MUST NOT be regarded as a valid email address.
3.4. UTF8 addresses and Response Codes
An internationalized message MUST NOT be sent to an SMTP server that
does not support UTF8SMTPbis. Such a message should be rejected by a
server if it lacks the support of UTF8SMTPbis.
The three-digit reply codes used in this section are consistent with
their meanings as defined in RFC 5321.
When messages are rejected because the RCPT command requires an ASCII
address, the response code 553 is used with the meaning "mailbox name
not allowed". When messages are rejected for other reasons, such as
the MAIL command requiring an ASCII address, the response code 550 is
used with the meaning "mailbox unavailable". When the server
supports enhanced mail system status codes [RFC3463], response code
"X.6.7" [RFC5248] is used, meaning that "UTF-8 addresses not
permitted for that sender/recipient".
If the response code is issued after the final "." of the DATA
command, the response code "554" is used with the meaning
"Transaction failed". When the server supports enhanced mail system
status codes [RFC3463], response code "X.6.9" [RFC5248] is used,
meaning that "UTF-8 header message can not be transferred to one or
more recipient so the message must be rejected".
3.5. Body Parts and SMTP Extensions
There is no ESMTP parameter to assert that a message is an
internationalized message. An SMTP server that requires accurate
knowledge of whether a message is internationalized is required to
parse all message header fields and MIME header fields [RFC2045] and
[RFC2047] in the message body.
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 [RFC2045] and
[RFC2047]. The UTF8SMTPbis extension MAY be used with the
BODY=8BITMIME parameter if that is appropriate given the body content
or, with the BODY=BINARYMIME parameter, if the server advertises
BINARYMIME [RFC3030] and that is appropriate.
Assuming that the server advertises UTF8SMTPbis and 8BITMIME, and
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receives at least one non-ASCII address, the precise interpretation
of "BODY=8BITMIME", and "BODY=BINARYMIME" in the MAIL command is:
1. If a BODY=8BITMIME parameter is present, the header contains
UTF-8 characters, and some or all of the body parts contain 8-bit
line-oriented data.
2. If a BODY=BINARYMIME parameter is present, the header contains
UTF-8 characters, and some or all body parts contain binary data
without restriction as to line lengths or delimiters.
3.6. Additional ESMTP Changes and Clarifications
The information carried in the mail transport process involves
addresses ("mailboxes") and domain names in various contexts in
addition to the MAIL and RCPT commands and extended alternatives to
them. In general, the rule is that, when RFC 5321 specifies a
mailbox, this specification expects UTF-8 to be used for the entire
string; when RFC 5321 specifies a domain name, the name SHOULD be in
the form of A-label if its raw form is non-ASCII.
The following subsections list and discuss all of the relevant cases.
3.6.1. The Initial SMTP Exchange
When an SMTP connection is opened, the server normally sends a
"greeting" response consisting of the 220 response code and some
information. The client then sends the EHLO command. Since the
client cannot know whether the server supports UTF8SMTPbis until
after it receives the response from EHLO, the client must send only
ASCII (LDH label [RFC5890] or A-label) domains in the EHLO command
and that, if the server provides domain names in the EHLO response,
they must be in the form of LDH labels or A-labels.
3.6.2. Mail eXchangers
Organizations often authorize multiple servers to accept mail
addressed to them. For example, the organization may itself operate
more than one server, and may also or instead have an agreement with
other organizations to accept mail as a backup. Authorized servers
are generally listed in MX records as described in RFC 5321. When
more than one server accepts mail for the domain-part of a mailbox,
it is strongly advised that either all or none of them support the
UTF8SMTPbis extension. Otherwise, surprising rejections can happen
during temporary failures, which users might perceive as a serious
reliability issue. In order to avoid the possible surprising
rejections, you may also implement the advice in EAI addresses advice
document [EAI addresses] and EAI deployment advice document [EAI
Deployment].
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3.6.3. Trace Information
When an SMTP server receives a message for delivery or further
processing, RFC 5321 requires that it MUST insert trace ("time stamp"
or "Received") information at the beginning of the message content.
For the trace information, this memo updates the time stamp line and
the return path line [RFC5321] formally defined as follows:
uReturn-path-line = "Return-Path:" FWS uReverse-path <CRLF>
; Replaces Return-path-line in Section 4.4 of RFC 5321
uReverse-path = uPath / "<>"
; Replace Reverse-path in RFC 5321, section 4.1.2
uPath = "<" [ A-d-l ":" ] uMailbox ">"
; Replace Path in RFC 5321, section 4.1.2
; uMailbox is defined in section 3.3 of this document
A-d-l = <See section 4.1.2 of RFC 5321>
uTime-stamp-line = "Received:" FWS uStamp <CRLF>
; Replaces Time-stamp-line in Section 4.4 of RFC 5321
uStamp = From-domain By-domain uOpt-info [CFWS] ";" FWS date-time
; Replaces Stamp in Section 4.4 of RFC 5321
From-domain = <See section 4.4 of RFC 5321>
By-domain = <See section 4.4 of RFC 5321>
date-time = <See section 3.3 of RFC 5322>
uOpt-info = [Via] [With] [ID] [uFor]
[Additional-Registered-Clauses]
; Replaces Opt-info in Section 4.4 of RFC 5321
; The protocol value for With will allow a UTF8SMTPbis value
Via = <See section 4.4 of RFC 5321>
With = <See section 4.4 of RFC 5321>
ID = <See section 4.4 of RFC 5321>
Additional-Registered-Clauses = <See section 4.4 of RFC 5321>
uFor = CFWS "FOR" FWS ( uPath / uMailbox)
; Replaces For in Section 4.4 of RFC 5321
; uMailbox is defined in section 3.3 of this document
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Except in the 'uFor' clause and 'uReverse-path' value where non-ASCII
domain names may be used, internationalized domain names in Received
fields MUST be transmitted in the form of A-labels. The protocol
value of the WITH clause when this extension is used is one of the
UTF8SMTPbis values specified in the "IANA Considerations" section of
this document.
3.6.4. UTF-8 Strings in Replies
3.6.4.1. RCPT Commands
If an SMTP client follows this specification and sends any RCPT
commands containing non-ASCII addresses, the SMTP server is permitted
to use UTF-8 characters in the email address associated with 251 and
551 response codes, and the client MUST be able to accept and process
them. If a given RCPT command does not include a non-ASCII envelope
address, the server MUST NOT return a 251 or 551 response containing
a non-ASCII mailbox. Instead, it MUST transform such responses into
250 or 550 responses that do not contain non-ASCII addresses.
3.6.4.2. VRFY and EXPN Commands and the UTF8REPLY Parameter
If the VRFY and EXPN commands are transmitted with the optional
parameter "UTF8REPLY", it indicates the client can accept UTF-8
strings in replies to those commands. This allows the server to use
UTF-8 strings in mailbox names and full names that occur in replies
without concern that the client might be confused by them. An SMTP
client that conforms to this specification MUST accept and correctly
process replies from the VRFY and EXPN commands that contain UTF-8
strings. However, the SMTP server MUST NOT use UTF-8 strings in
replies if the SMTP client does not specifically allow such replies
by transmitting this parameter. Most replies do not require that a
mailbox name be included in the returned text, and therefore UTF-8 is
not needed in them. Some replies, notably those resulting from
successful execution of the VRFY and EXPN commands, do include the
mailbox, making the provisions of this section important.
VERIFY (VRFY) and EXPAND (EXPN) command syntaxes are changed to:
vrfy = "VRFY" SP ( uLocal-part / uMailbox )
[ SP "UTF8REPLY" ] CRLF
; uLocal-part and uMailbox are defined in
; Section 3.3 of this document.
expn = "EXPN" SP ( uLocal-part / uMailbox )
[ SP "UTF8REPLY" ] CRLF
; uLocal-part and uMailbox are defined in
; Section 3.3 of this document.
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The "UTF8REPLY" parameter does not use a value. If the reply to a
VERIFY (VRFY) or EXPAND (EXPN) command requires UTF-8, but the SMTP
client did not use the "UTF8REPLY" parameter, then the server MUST
use either the response code 252 or 550. Response code 252, defined
in [RFC5321], means "Cannot VRFY user, but will accept the message
and attempt the delivery". Response code 550, also defined in
[RFC5321], means "Requested action not taken: mailbox unavailable".
When the server supports enhanced mail system status codes [RFC3463],
the enhanced response code as specified below is used. Using the
"UTF8REPLY" parameter with a VERIFY (VRFY) or EXPAND (EXPN) command
enables UTF-8 replies for that command only.
If a normal success response (i.e., 250) is returned, the response
MAY include the full name of the user and MUST include the mailbox of
the user. It MUST be in either of the following forms:
User Name <uMailbox>
; uMailbox is defined in Section 3.3 of this document.
; User Name can contain non-ASCII characters.
uMailbox
; uMailbox is defined in Section 3.3 of this document.
If the SMTP reply requires UTF-8 strings, but UTF-8 is not allowed in
the reply, and the server supports enhanced mail system status codes
[RFC3463], the enhanced response code [RFC5248] is either "X.6.8" if
the associated basic status code [RFC5321] is 252 or "Y.6.8" if the
associated basic status code [RFC5321] is 553 or 550, meaning "A
reply containing a UTF-8 string is required to show the mailbox name,
but that form of response is not permitted by the client".
If the SMTP client does not support the UTF8SMTPbis extension, but
receives a UTF-8 string in a reply, it may not be able to properly
report the reply to the user, and some clients might crash.
Internationalized messages in replies are only allowed in the
commands under the situations described above. Under any other
circumstances, UTF-8 text MUST NOT appear in the reply.
Although UTF-8 is needed to represent email addresses in responses
under the rules specified in this section, this extension does not
permit the use of UTF-8 for any other purposes. SMTP servers MUST
NOT include non-ASCII characters in replies except in the limited
cases specifically permitted in this section.
4. IANA Considerations
IANA should add a new value "UTF8SMTPbis" to the SMTP Service
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Extension subregistry of the Mail Parameters registry, according to
the following data:
+-------------+---------------------------------+-----------+
| Keywords | Description | Reference |
+-------------+---------------------------------+-----------+
| UTF8SMTPbis | Internationalized email address | [RFCXXXX] |
+-------------+---------------------------------+-----------+
This document updates the values to the SMTP Enhanced Status Code
subregistry of the Mail Parameters registry, following the guidance
in Sections 3.4 and 3.6.4.2 of this document, and being based on
[RFC5248]. The registration data is as follows:
Code: X.6.7
Sample Text: UTF-8 addresses not permitted
for that sender/recipient
Associated basic status code: 553, 550
Description: This indicates the reception of a MAIL or RCPT
command that rUTF-8 addresses are not permitted
Defined: RFC XXXX (Standard track)
Submitter: Jiankang YAO
Change controller: ima@ietf.org
Code: X.6.8
Sample Text: UTF-8 string reply is required,
but not permitted by the client
Associated basic status code: 553, 550
Description: This indicates that a reply containing a UTF-8
string is required to show the mailbox name,
but that form of response is not
permitted by the client.
Defined: RFC XXXX (Standard track)
Submitter: Jiankang YAO
Change controller: ima@ietf.org
Code: X.6.9
Sample Text: UTF-8 header message can not be transferred
to one or more recipient so the message
must be rejected
Associated basic status code: 550
Description: This indicates that transaction failed
after the final "." of the DATA command.
Defined: RFC XXXX (Standard track)
Submitter: Jiankang YAO
Change controller: ima@ietf.org
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Code: Y.6.8
Sample Text: UTF-8 string reply is required,
but not permitted by the client
Associated basic status code: 252
Description: This indicates that a reply containing a UTF-8
string is required to show the mailbox name,
but that form of response is not
permitted by the client.
Defined: RFC XXXX (Standard track)
Submitter: Jiankang YAO
Change controller: ima@ietf.org
The "Mail Transmission Types" registry under the Mail Parameters
registry is requested to be updated to include the following new
entries:
+---------------+-----------------------------+---------------------+
| WITH protocol | Description | Reference |
| types | | |
+---------------+-----------------------------+---------------------+
| UTF8SMTPbis | UTF8SMTPbis with Service | [RFCXXXX] |
| | Extensions | |
| UTF8SMTPbisA | UTF8SMTPbis with SMTP AUTH | [RFC4954] [RFCXXXX] |
| UTF8SMTPbisS | UTF8SMTPbis with STARTTLS | [RFC3207] [RFCXXXX] |
| UTF8SMTPbisSA | UTF8SMTPbis with both | [RFC3207] [RFC4954] |
| | STARTTLS and SMTP AUTH | [RFCXXXX] |
+---------------+-----------------------------+---------------------+
5. Security Considerations
See the extended security considerations discussion in the framework
document [RFC4952bis].
6. Acknowledgements
This document revised the [RFC5336]document based on the EAI WG's
discussion result. Many EAI WG members did some tests and
implementations to move this document to the Standard Track document.
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 specification. Additional
important comments and suggestions, and often specific text, were
contributed by many members of the WG and design team. Those
contributions include material from John C Klensin, Charles Lindsey,
Dave Crocker, Harald Tveit Alvestrand, Marcos Sanz, Chris Newman,
Martin Duerst, Edmon Chung, Tony Finch, Kari Hurtta, Randall Gellens,
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Frank Ellermann, Alexey Melnikov, Pete Resnick, S. Moonesamy, Soobok
Lee, Shawn Steele, Alfred Hoenes, Miguel Garcia, Magnus Westerlund,
and Lars Eggert. Of course, none of the individuals are necessarily
responsible for the combination of ideas represented here.
7. Change History
[[anchor11: RFC Editor: Please remove this section.]]
7.1. draft-yao-eai-rfc5336bis: Version 00
Applied errata suggested by Alfred Hoenes.
7.2. draft-ietf-eai-rfc5336bis: Version 00
Applied the changes suggested by the EAI new charter.
7.3. draft-ietf-eai-rfc5336bis: Version 01
Applied the changes suggested by 78 IETF EAI meeting.
7.4. draft-ietf-eai-rfc5336bis: Version 02
remove the appendix since rfc4952bis has added this material
improve the text
remove the text about no body parameter
7.5. draft-ietf-eai-rfc5336bis: Version 03
improve the text
7.6. draft-ietf-eai-rfc5336bis: Version 04
update the abstract
improve the text
7.7. draft-ietf-eai-rfc5336bis: Version 05
improve the text based on AD and Co-chairs
8. References
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8.1. Normative References
[ASCII] American National Standards Institute (formerly United
States of America Standards Institute), "USA Code for
Information Interchange", ANSI X3.4-1968, 1968.
[RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extension for 8bit-MIMEtransport",
RFC 1652, July 1994.
[RFC2033] Myers, J., "Local Mail Transfer Protocol", RFC 2033,
October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3463] Vaudreuil, G., "Enhanced Mail System Status Codes",
RFC 3463, January 2003.
[RFC3464] Moore, K. and G. Vaudreuil, "An Extensible Message Format
for Delivery Status Notifications", RFC 3464,
January 2003.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", RFC 3629, November 2003.
[RFC4409] Gellens, R. and J. Klensin, "Message Submission for Mail",
RFC 4409, April 2006.
[RFC4952bis]
Klensin, J. and Y. Ko, "Overview and Framework for
Internationalized Email", RFC 4952, July 2010.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5248] Hansen , T. and J. Klensin, "A Registry for SMTP Enhanced
Mail System Status Codes", RFC 5248, June 2008.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
October 2008.
[RFC5335bis]
Abel, Y. and S. Steel, "Internationalized Email Headers",
RFC 5335, December 2010.
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Internet-Draft EAI SMTP Extension December 2010
[RFC5337bis]
Newman, C. and A. Melnikov, Ed., "Internationalized
Delivery Status and Disposition Notifications", RFC 5337,
August 2008.
[RFC5890] Klensin, J., "Internationalizing Domain Names in
Applications (IDNA definitions)", RFC 5890, June 2010.
[RFC5891] Klensin, J., "Internationalized Domain Names in
Applications (IDNA): Protocol", RFC 5891, August 2010.
8.2. Informative References
[EAI Deployment]
Yao, J., Lee, X., and S. Steel, "Advice for EAI
deployment", draft 5335, December 2010.
[EAI addresses]
Steel, S., Yao, J., and Mark. Davis, "Advice for non-ASCII
& ASCII addresses", draft 5335, December 2010.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
Part Three: Message Header Extensions for Non-ASCII Text",
RFC 2047, November 1996.
[RFC3030] Vaudreuil, G., "SMTP Service Extensions for Transmission
of Large and Binary MIME Messages", RFC 3030,
December 2000.
[RFC3207] Hoffman, P., "SMTP Service Extension for Secure SMTP over
Transport Layer Security", RFC 3207, February 2002.
[RFC4954] Siemborski, R. and A. Melnikov, "SMTP Service Extension
for Authentication", RFC 4954, July 2007.
[RFC5336] Yao, J. and W. Mao, "SMTP Extension for Internationalized
Email Addresses", RFC 5336, September 2008.
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Authors' Addresses
Jiankang YAO
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing
Phone: +86 10 58813007
Email: yaojk@cnnic.cn
Wei MAO
CNNIC
No.4 South 4th Street, Zhongguancun
Beijing
Phone: +86 10 58812230
Email: maowei_ietf@cnnic.cn
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