draft-ietf-eai-rfc5336bis-03.txt   draft-ietf-eai-rfc5336bis-04.txt 
Network Working Group Jiankang. Yao Network Working Group Jiankang. Yao
Internet-Draft Wei. Mao Internet-Draft Wei. Mao
Obsoletes: RFC5336 CNNIC Obsoletes: RFC5336 CNNIC
(if approved) September 26, 2010 (if approved) October 21, 2010
Updates: RFC5321 and 5322 Updates: RFC5321 and 5322
(if approved) (if approved)
Intended status: Standards Track Intended status: Standards Track
Expires: March 30, 2011 Expires: April 24, 2011
SMTP Extension for Internationalized Email Address SMTP Extension for Internationalized Email Address
draft-ietf-eai-rfc5336bis-03.txt draft-ietf-eai-rfc5336bis-04.txt
Abstract Abstract
This document specifies an SMTP extension for transport and delivery This document specifies an SMTP extension for transport and delivery
of email messages with internationalized email addresses or header of email messages with internationalized email addresses or header
information. Communication with systems that do not implement this information. This document updates some syntaxes and rules defined
specification is specified in another document. This document in RFC 5321 and RFC 5322.
updates some syntaxes and rules defined in RFC 5321 and RFC 5322.
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 March 30, 2011. This Internet-Draft will expire on April 24, 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
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modifications of such material outside the IETF Standards Process. modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other it for publication as an RFC or to translate it into languages other
than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Role of This Specification . . . . . . . . . . . . . . . . 4 1.1. Role of This Specification . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview of Operation . . . . . . . . . . . . . . . . . . . . 5 2. Overview of Operation . . . . . . . . . . . . . . . . . . . . 4
3. Mail Transport-Level Protocol . . . . . . . . . . . . . . . . 5 3. Mail Transport-Level Protocol . . . . . . . . . . . . . . . . 4
3.1. Framework for the Internationalization Extension . . . . . 5 3.1. Framework for the Internationalization Extension . . . . . 4
3.2. The UTF8SMTPbis Extension . . . . . . . . . . . . . . . . 6 3.2. The UTF8SMTPbis Extension . . . . . . . . . . . . . . . . 5
3.3. Extended Mailbox Address Syntax . . . . . . . . . . . . . 7 3.3. Extended Mailbox Address Syntax . . . . . . . . . . . . . 6
3.4. UTF8 addresses and Response Codes . . . . . . . . . . . . 8 3.4. UTF8 addresses and Response Codes . . . . . . . . . . . . 7
3.5. Body Parts and SMTP Extensions . . . . . . . . . . . . . . 8 3.5. Body Parts and SMTP Extensions . . . . . . . . . . . . . . 7
3.6. Additional ESMTP Changes and Clarifications . . . . . . . 9 3.6. Additional ESMTP Changes and Clarifications . . . . . . . 8
3.6.1. The Initial SMTP Exchange . . . . . . . . . . . . . . 9 3.6.1. The Initial SMTP Exchange . . . . . . . . . . . . . . 8
3.6.2. Mail eXchangers . . . . . . . . . . . . . . . . . . . 9 3.6.2. Mail eXchangers . . . . . . . . . . . . . . . . . . . 8
3.6.3. Trace Information . . . . . . . . . . . . . . . . . . 10 3.6.3. Trace Information . . . . . . . . . . . . . . . . . . 9
3.6.4. UTF-8 Strings in Replies . . . . . . . . . . . . . . . 11 3.6.4. UTF-8 Strings in Replies . . . . . . . . . . . . . . . 10
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
7. Change History . . . . . . . . . . . . . . . . . . . . . . . . 15 7. Change History . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. draft-yao-eai-rfc5336bis: Version 00 . . . . . . . . . . . 15 7.1. draft-yao-eai-rfc5336bis: Version 00 . . . . . . . . . . . 14
7.2. draft-ietf-eai-rfc5336bis: Version 00 . . . . . . . . . . 15 7.2. draft-ietf-eai-rfc5336bis: Version 00 . . . . . . . . . . 14
7.3. draft-ietf-eai-rfc5336bis: Version 01 . . . . . . . . . . 15 7.3. draft-ietf-eai-rfc5336bis: Version 01 . . . . . . . . . . 14
7.4. draft-ietf-eai-rfc5336bis: Version 02 . . . . . . . . . . 15 7.4. draft-ietf-eai-rfc5336bis: Version 02 . . . . . . . . . . 14
7.5. draft-ietf-eai-rfc5336bis: Version 03 . . . . . . . . . . 15 7.5. draft-ietf-eai-rfc5336bis: Version 03 . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7.6. draft-ietf-eai-rfc5336bis: Version 04 . . . . . . . . . . 14
8.1. Normative References . . . . . . . . . . . . . . . . . . . 15 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.2. Informative References . . . . . . . . . . . . . . . . . . 17 8.1. Normative References . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 8.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
An internationalized email address includes two parts, the local part An internationalized email address includes two parts, the local part
and the domain part. The ways email addresses are used by protocols and the domain part. The ways email addresses are used by protocols
are different from the ways domain names are used. The most critical are different from the ways domain names are used. The most critical
difference is that emails are delivered through a chain of clients difference is that emails are delivered through a chain of clients
and servers, while domain names are resolved by name servers looking and servers, while domain names are resolved by name servers looking
up those names in their own tables. In addition to this, the Simple up those names in their own tables. The Simple Mail Transfer
Mail Transfer Protocol [RFC5321] provides a negotiation mechanism Protocol [RFC5321] provides a negotiation mechanism about service
about service extension with which clients can discover server extension with which clients can discover server capabilities and
capabilities and make decisions for further processing. An extended make decisions for further processing. An extended overview of the
overview of the extension model for internationalized addresses and extension model for internationalized addresses and headers appears
headers appears in [RFC4952bis], referred to as "the framework in [RFC4952bis], referred to as "the framework document" or just as
document" or just as "framework" elsewhere in this specification. "framework" elsewhere in this specification. This document specifies
This document specifies an SMTP extension to permit internationalized an SMTP extension to permit internationalized email addresses in
email addresses in envelopes, and UNICODE characters (encoded in envelopes, and UNICODE characters (encoded in UTF-8) [RFC3629] in
UTF-8) [RFC3629] in headers. headers.
1.1. Role of This Specification 1.1. Role of This Specification
The framework document specifies the requirements for, and describes The framework document specifies the requirements for, and describes
components of, full internationalization of the electronic mail. A components of, full internationalization of the electronic mail. A
thorough understanding of the information in that document and in the thorough understanding of the information in that document and in the
base Internet email specifications [RFC5321] [RFC5322] is necessary base Internet email specifications [RFC5321] [RFC5322] is necessary
to understand and implement this specification. to understand and implement this specification.
This document specifies an element of the email internationalization This document specifies an element of the email internationalization
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MUST be compared as specified in section 3 of [RFC5891]. MUST be compared as specified in section 3 of [RFC5891].
An SMTP client that receives the UTF8SMTPbis extension keyword in An SMTP client that receives the UTF8SMTPbis extension keyword in
response to the EHLO command MAY transmit mailbox names within SMTP response to the EHLO command MAY transmit mailbox names within SMTP
commands as internationalized strings in UTF-8 form. It MAY send a 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 header [RFC5335bis] (which may also include mailbox names in
UTF-8). It MAY transmit the domain parts of mailbox names within UTF-8). It MAY transmit the domain parts of mailbox names within
SMTP commands or the message header as either ACE (ASCII Compatible SMTP commands or the message header as either ACE (ASCII Compatible
Encoding) labels (as specified in IDNA definitions [RFC5890]) or Encoding) labels (as specified in IDNA definitions [RFC5890]) or
UTF-8 strings. All labels in domain parts of mailbox names which are UTF-8 strings. All labels in domain parts of mailbox names which are
IDNs (either UTF-8 or ACE strings) MUST be valid. If the original IDNs (either UTF-8 or ACE strings) MUST be valid. When a Message
client submits a message to a Message Submission Server ("MSA") User Agent submits a message to a Message Submission Server
[RFC4409], it is the responsibility of the MSA that all domain labels ("MSA")[RFC4409], it is the responsibility of the MSA to ensure that
are valid; otherwise, it is the original client's responsibility. all domain labels are valid. The presence of the UTF8SMTPbis
The presence of the UTF8SMTPbis extension does not change the extension does not change the requirement of RFC 5321 that servers
requirement of RFC 5321 that servers relaying mail MUST NOT attempt relaying mail MUST NOT attempt to parse, evaluate, or transform the
to parse, evaluate, or transform the local part in any way. local part in any way.
If the UTF8SMTPbis SMTP extension is not offered by the server, the If the UTF8SMTPbis SMTP extension is not offered by the server, the
SMTP client MUST NOT transmit an internationalized address and MUST SMTP client MUST NOT transmit an internationalized address and MUST
NOT transmit a mail message containing internationalized mail headers NOT transmit a mail message containing internationalized mail headers
as described in [RFC5335bis] at any level within its MIME structure as described in [RFC5335bis] at any level within its MIME structure
[RFC2045] and [RFC2047]. (For this paragraph, the internationalized [RFC2045] and [RFC2047]. (For this paragraph, the internationalized
domain name in the form of ACE labels as specified in IDNA domain name in the form of ACE labels as specified in IDNA
definitions [RFC5890] is not considered to be "internationalized".) definitions [RFC5890] is not considered to be "internationalized".)
Instead, if an SMTP client (SMTP sender) attempts to transfer an Instead, if an SMTP client (SMTP sender) attempts to transfer an
internationalized message and encounters a server that does not internationalized message and encounters a server that does not
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RFC 5321) or using other means available to the SMTP-sender. RFC 5321) or using other means available to the SMTP-sender.
This document applies only when an UTF8SMTPbis-aware client is trying This document applies only when an UTF8SMTPbis-aware client is trying
to send an internationalized message to a server which requires the to send an internationalized message to a server which requires the
UTF8SMTPbis extensions to handle it. For all other cases, and for UTF8SMTPbis extensions to handle it. For all other cases, and for
addresses and messages that do not require an UTF8SMTPbis extension, addresses and messages that do not require an UTF8SMTPbis extension,
SMTP clients and servers are expected to behave exactly as specified SMTP clients and servers are expected to behave exactly as specified
in [RFC5321]. in [RFC5321].
A UTF8SMTPbis aware MUA/MSA sending to a legacy SMTP server [RFC5321] A UTF8SMTPbis aware MUA/MSA sending to a legacy SMTP server [RFC5321]
and [RFC5322] MAY convert the ASCII@non-ASCII addresse into the and [RFC5322] MAY convert the ASCII@non-ASCII address into the format
format of ASCII@A-label [RFC5890] if the email address is in the of ASCII@A-label [RFC5890] if the email address is in the format of
format of ASCII@non-ASCII. ASCII@non-ASCII.
3.3. Extended Mailbox Address Syntax 3.3. Extended Mailbox Address Syntax
RFC 5321, Section 4.1.2, defines the syntax of a mailbox entirely in 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 terms of ASCII characters, using the production for a mailbox and
those productions on which it depends. those productions on which it depends.
The key changes made by this specification are, informally, to The key changes made by this specification are, informally, to
o Change the definition of "Domain" to permit either the definition o Change the definition of "Domain" to permit either the definition
above or a UTF-8 string representing a DNS label that is above or a UTF-8 string representing a DNS label that is
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the MAIL command requiring an ASCII address, the response code 550 is the MAIL command requiring an ASCII address, the response code 550 is
used with the meaning "mailbox unavailable". When the server used with the meaning "mailbox unavailable". When the server
supports enhanced mail system status codes [RFC3463], response code supports enhanced mail system status codes [RFC3463], response code
"X.6.7" [RFC5248] is used, meaning that "UTF-8 addresses not "X.6.7" [RFC5248] is used, meaning that "UTF-8 addresses not
permitted for that sender/recipient". permitted for that sender/recipient".
If the response code is issued after the final "." of the DATA If the response code is issued after the final "." of the DATA
command, the response code "554" is used with the meaning command, the response code "554" is used with the meaning
"Transaction failed". When the server supports enhanced mail system "Transaction failed". When the server supports enhanced mail system
status codes [RFC3463], response code "X.6.9" [RFC5248] is used, status codes [RFC3463], response code "X.6.9" [RFC5248] is used,
meaning that "UTF-8 header message can't be transferred to one or meaning that "UTF-8 header message can not be transferred to one or
more recipient so the message must be bounced". more recipient so the message must be bounced".
3.5. Body Parts and SMTP Extensions 3.5. Body Parts and SMTP Extensions
There is no ESMTP parameter to assert that a message is an There is no ESMTP parameter to assert that a message is an
internationalized message. An SMTP server that requires accurate internationalized message. An SMTP server that requires accurate
knowledge of whether a message is internationalized is required to knowledge of whether a message is internationalized is required to
parse all message header fields and MIME header fields [RFC2045] and parse all message header fields and MIME header fields [RFC2045] and
[RFC2047] in the message body. [RFC2047] in the message body.
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Associated basic status code: 553, 550 Associated basic status code: 553, 550
Description: This indicates that a reply containing a UTF-8 Description: This indicates that a reply containing a UTF-8
string is required to show the mailbox name, string is required to show the mailbox name,
but that form of response is not but that form of response is not
permitted by the client. permitted by the client.
Defined: RFC XXXX (Standard track) Defined: RFC XXXX (Standard track)
Submitter: Jiankang YAO Submitter: Jiankang YAO
Change controller: IESG. Change controller: IESG.
Code: X.6.9 Code: X.6.9
Sample Text: UTF-8 header message can't be transferred Sample Text: UTF-8 header message can not be transferred
to one or more recipient so the message to one or more recipient so the message
must be bounced must be bounced
Associated basic status code: 550 Associated basic status code: 550
Description: This indicates that transaction failed Description: This indicates that transaction failed
after the final "." of the DATA command. after the final "." of the DATA command.
Defined: RFC XXXX (Standard track) Defined: RFC XXXX (Standard track)
Submitter: Jiankang YAO Submitter: Jiankang YAO
Change controller: IESG. Change controller: IESG.
Code: X.6.10 Code: X.6.10
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remove the appendix since rfc4952bis has added this material remove the appendix since rfc4952bis has added this material
improve the text improve the text
remove the text about no body parameter remove the text about no body parameter
7.5. draft-ietf-eai-rfc5336bis: Version 03 7.5. draft-ietf-eai-rfc5336bis: Version 03
improve the text improve the text
7.6. draft-ietf-eai-rfc5336bis: Version 04
update the abstract
improve the text
8. References 8. References
8.1. Normative References 8.1. Normative References
[ASCII] American National Standards Institute (formerly United [ASCII] American National Standards Institute (formerly United
States of America Standards Institute), "USA Code for States of America Standards Institute), "USA Code for
Information Interchange", ANSI X3.4-1968, 1968. Information Interchange", ANSI X3.4-1968, 1968.
[RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D. [RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extension for 8bit-MIMEtransport", Crocker, "SMTP Service Extension for 8bit-MIMEtransport",
 End of changes. 12 change blocks. 
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