Email Address Internationalization J. Klensin
(EAI)
Internet-Draft Y. Ko
Expires: November 25, 2006 MOCOCO, Inc.
May 24, 2006
Overview and Framework for Internationalized Email
draft-ietf-eai-framework-00.txt
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Copyright (C) The Internet Society (2006).
Abstract
Full use of electronic mail throughout the world requires that people
be able to use their own names, written correctly in their own
languages and scripts, as mailbox names in email addresses. This
document introduces a series of specifications and operational
suggestions that define mechanisms and protocol extensions needed to
fully support internationalized email addresses. These changes
include an SMTP extension and extension of email header syntax to
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accommodate UTF-8 data. The document set also will include
discussion of key assumptions and issues in deploying fully
internationalized email.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Role of This Specification . . . . . . . . . . . . . . . . 3
1.2. Problem statement . . . . . . . . . . . . . . . . . . . . 3
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Overview of the Approach . . . . . . . . . . . . . . . . . . . 5
3. Document Roadmap . . . . . . . . . . . . . . . . . . . . . . . 6
4. Overview of Protocol Extensions and Changes . . . . . . . . . 6
4.1. SMTP Extension for Internationalized eMail Address . . . . 6
4.2. Transmission of Email Header in UTF-8 Encoding . . . . . . 7
4.3. Downgrading Mechanism for Backward Compatibility . . . . . 8
5. Downgrading Before and After SMTP Transactions . . . . . . . . 8
5.1. Downgrading Before or During Message Submission . . . . . 9
5.2. Downgrading or Other Processing After Final SMTP
Delivery . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. Advice to Designers and Operators of Mail-receiving Systems . 10
7. Internationalization Considerations . . . . . . . . . . . . . 10
8. Additional Issues . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Impact on IRIs . . . . . . . . . . . . . . . . . . . . . . 11
8.2. POP and IMAP . . . . . . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Security Considerations . . . . . . . . . . . . . . . . . . . 11
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
12. Change History . . . . . . . . . . . . . . . . . . . . . . . . 12
12.1. draft-klensin-ima-framework: Version 00 . . . . . . . . . 13
12.2. draft-klensin-ima-framework: Version 01 . . . . . . . . . 13
12.3. draft-ietf-eai-framework: Version 00 . . . . . . . . . . . 13
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
13.1. Normative References . . . . . . . . . . . . . . . . . . . 13
13.2. Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . . . . 19
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1. Introduction
[[anchor1: NOTE IN DRAFT: The next version of this document (-01)
will include references that are updated as appropriate to utilize
the new names of documents and a list of documents that are
harmonized with the WG Charter. This version is transitional and
those reading it are asked to be tolerant of the transition.]]
In order to use internationalized email addresses, we need to
internationalize both domain part and local part of email address.
The domain part of email addresses is already internationalized
[RFC3490], while the local part is not. Without these extensions,
the mailbox name is restricted to a subset of 7-bit ASCII in
[RFC2821]. Though MIME enables the transport of non-ASCII data, it
does not provide a mechanism for internationalized email address.
[RFC2047] defines an encoding mechanism for some specific message
header fields to accommodate non-ASCII data. However, it does not
address the issue of email addresses that include non-ASCII
characters. Without the extensions defined here, or some equivalent
set, the only way to incorporate non-ASCII characters in email
addresses is to use RFC2047 coding to embed them in what RFC 2822
[RFC2822] calls the "display name" (known as a "name phrase" or by
other terms elsewhere) of the relevant headers. Of course, that type
of coding is invisible in the message envelope and would not be
considered by many to be part of the address at all.
1.1. Role of This Specification
This document presents the overview and framework for an approach to
the next stage of email internationalization. This new stage
requires not only internationalization of addresses and headers, but
also associated transport and delivery models. The history of
developments and design ideas leading to this specification is
described in [I18Nemail-history].
This document describes how the various elements of email
internationalization fit together and provides a roadmap for
navigating the various documents involved.
1.2. Problem statement
[[anchor2: Note in draft: this section needs very significant
reworking for both content and presentation. Changed with -01c, but
may still not be good enough]]
Though domain names are already internationalized, the
internationalized forms are far from general adoption by ordinary
users. One of the reasons for this is that we do not yet have fully
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internationalized naming schemes. Domain names are just one of the
various names and identifiers that are required to be
internationalized.
Email addresses are a particularly important example of where
internationalization of domain names alone is not sufficient. Unless
email addresses are presented to the user in familiar characters and
formats, the user's perception will not be of internationalization
and behavior that is culturally friendly. One thing most of us have
almost certainly learned from the experience with email usage is that
users strongly prefer email addresses that closely resemble names or
initials to those involving meaningless strings of letters or
numbers. If the names or initials of the names in the email address
can be expressed in the native languages and writing systems of the
users, the Internet will be perceived as more natural by those whose
native language is not written in a subset of a Roman-derived script
(this is the same collection of characters known as "Latin" in
Unicode Consortium and ISO/IEC JTC1 publications. In much of the
linguistic literature, the term "Latin Script" is used exclusively
for the characters used to write the Latin language at the time of
the Roman Republic, so its use for all characters constructed from
that base has been a source of confusion.).
Internationalization of email addresses is not merely a matter of
changing the SMTP envelope, or of modifying the From, To, and Cc
headers, or of permitting upgraded mail user agents (MUAs) to decode
a special coding and display local characters. To be perceived as
usable by end users, the addresses must be internationalized, and
handled consistently, in all of the contexts in which they occur.
That requirement has far-reaching implications: collections of
patches and workarounds are not adequate. Even if they were
adequate, that approach risks an assortment of implementations with
different sets of patches and workarounds having been applied with
consequent user confusion about what is actually be run and
supported. Instead, we need to build a fully internationalized email
environment, focusing on permitting efficient communication among
those who share a language or other community (see [I18Nemail-
constraints] for an extended discussion of this optimization). That,
in turn, implies changes to the mail header environment to permit the
full range of Unicode characters where that makes sense, an SMTP
extension to permit UTF-8 [RFC3629] mail addressing and delivery of
those extended headers, and (finally) a requirement for support of
the 8BITMIME option so that all of this can be transported through
the mail system without having to overcome the limitation that
headers do not have content-transfer-encodings.
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1.3. Terminology
This document assumes a reasonable understanding of the protocols and
terminology of the core email standards as documented in [RFC2821]
and [RFC2822].
Much of the description in this document depends on the abstractions
of "Mail Transfer Agent" ("MTA") and "Mail User Agent" ("MUA").
However, it is important to understand that those terms and the
underlying concepts postdate the design of the Internet's email
architecture and the "protocols on the wire" principle. That email
architecture, as it has evolved, and the "wire" principle have
prevented any strong and standardized distinctions about how MTAs and
MUAs interact on a given origin or destination host (or even whether
they are separate).
In this document, an address is "all-ASCII" if every character in the
address is in the ASCII character repertoire [ASCII]; an address is
"non-ASCII" if any character is not in the ASCII character
repertoire. The term "all-ASCII" is also applied to other protocol
elements when the distinction is important, with "non-ASCII" or
"internationalized" as its opposite.
The term "internationalized email address", or "EAI", refers to an
address permitted by this specification. [[anchor4: Note in Draft/
Placeholder: it appears that the terms "EAI" and the earlier "IMA"
are not used in a precise and consistent way across the document set.
It is sometimes used to refer simply to a "non-ASCII" address;
sometimes to an address that contains non-ASCII characters, even if
that address is encoded into ASCII characters (i.e., as an ACE); and
sometimes as an address that may contain non-ASCII characters but may
also be a traditional address. The definition needs to be clarified
in an upcoming draft and all uses of the term brought into line with
the definition.]]
The key words "MUST", "SHALL", "REQUIRED", "SHOULD", "RECOMMENDED",
and "MAY" in this document are to be interpreted as described in RFC
2119 [RFC2119].
2. Overview of the Approach
This set of specifications changes both SMTP and the format of email
headers to permit non-ASCII characters to be represented directly.
Each important component of the work is described in a separate
document. The document set, whose members are described in the next
section, also contains informational documents whose purpose is to
provide operational and implementation suggestions and guidance for
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the protocols.
3. Document Roadmap
In addition to this document, the following documents make up this
specification and provide advice and context for it.
o SMTP extensions. This document provides an SMTP extension for
internationalized addresses, as provided for in RFC 2821
[I18Nemail-SMTPext].
o Email headers in UTF-8. This document essentially updates RFC
2822 to permit some information in email headers to be expressed
directly by Unicode characters encoded in UTF-8 when the SMTP
extension is used [I18Nemail-UTF8].
o In-transit downgrading from internationalized addressing with the
SMTP extension and UTF-8 headers to traditional email formats and
characters [I18Nemail-downgrade]. Downgrading either at the point
of message origination or after the mail has successfully been
received by a final delivery SMTP server (sometimes called an
"MDA") involve different constraints and possibilities; see
Section 4.3 and Section 5, below.
o Extensions to the IMAP and POP protocols to support
internationalized headers [I18Nemail-imap] and [I18Nemail-pop].
o Operational guidelines and suggestions for the deployment of
internationalized email [I18Nemail-ops].
o Special considerations for mailing lists and similar distributions
during the transition to internationalized email [I18Nemail-
Exploder].
o Design decisions, history, and alternative models for
internationalized Internet email [I18Nemail-history].
4. Overview of Protocol Extensions and Changes
4.1. SMTP Extension for Internationalized eMail Address
An SMTP extension, "Email18N" [[anchor8: Extension name should be
corrected when we make a final decision and synchronized with the
"I18Nemail-SMTPext" document]] is specified that
o Permits the use of UTF-8 strings in email addresses, both local
parts and domain names
o Permits the selective use of UTF-8 strings in email headers (see
the next subsection)
o Requires that the server advertise the 8BITMIME extension
[RFC1652] and that the client support 8-bit transmission so that
header information can be transmitted without using a special
content-transfer-encoding.
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o Provides information to support downgrading mechanisms.
Some general principles apply to this work.
1. Whatever encoding is used should apply to the whole address and
be directly compatible with software used at the user interface.
2. An SMTP relay must
* Either recognize the format explicitly, agreeing to do so via
an ESMTP option,
* Select and use an ASCII-only address, or
* Bounce the message so that the sender can make another plan.
If the message cannot be forwarded because the next-hop system
cannot accept the extension and insufficient information is
available to reliably downgrade it, it MUST be bounced.
3. In the interest of interoperability, charsets other than UTF-8
are prohibited. There is no practical way to identify them
properly with an extension similar to this without introducing
great complexity.
Conformance to the group of standards specified here for email
transport and delivery requires implementation of the SMTP Extension
specification, including recognition of the keywords associated with
alternate and synthesized addresses, and the UTF-8 Header
specification. Support for downgrading is not required, but, if
implemented, MUST be implemented as specified.
4.2. Transmission of Email Header in UTF-8 Encoding
There are many places in MUAs or in user presentation in which email
addresses or domain names appear. Examples include the conventional
From, To, or Cc header fields; Message-IDs; In-Reply-To fields that
may contain addresses or domain names; in message bodies; or
elsewhere. We must examine all of them from an internationalization
perspective. The user will expect to see mailbox and domain names in
local characters, and to see them consistently. If non-obvious
encodings, such as protocol-specific ACE variants, are used, the user
will inevitably see them, at least occasionally, rather than "native"
characters and will find that discomfiting or astonishing.
Similarly, if different codings are used for mail transport and
message bodies, the user is particularly likely to be surprised, if
only as a consequence of the long-established "things leak"
principle. But the only practical way to avoid these sources of
discomfort, in both the medium and the longer term, is to have the
encodings used in transport be as nearly as possible the same as the
encodings used in message headers and message bodies.
It seems clear that the point at which email local parts are
internationalized is the point that email headers should simply be
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shifted to a full internationalized form, presumably using UTF-8
rather than ASCII as the base character set for other than protocol
elements such as the header field names themselves. The transition
to that model includes support for address, and address-related,
fields within the headers of legacy systems. This is done by
extending the encoding models of [RFC2045] and [RFC2231]. However,
our target should be fully internationalized headers, as discussed
[I18Nemail-UTF8].
4.3. Downgrading Mechanism for Backward Compatibility
As with any use of the SMTP extension mechanism, there is always a
possibility of a client that requires the feature encountering a
server that does not. In the case of email address and header
internationalization, the risk should be minimized by the fact that
the selection of submission servers are presumably under the control
of the sender's client and the selection of potential intermediate
relays is under the control of the administration of the final
delivery server.
For those situations, there are basically two possibilities:
o Reject or bounce the message, requiring the sender to resubmit it
with traditional-format addresses and headers.
o Figure out a way to downgrade the envelope or message body in
transit. Especially when internationalized addresses are
involved, downgrading will require either that an all-ASCII
address be obtained from some source or computed. An optional
extension parameter is provided as a way of transmitting an
alternate address. Computing an all-ASCII form of a non-ASCII
address requires that the sender have some knowledge. This
knowledge is normally restricted to final delivery servers, but
some extensions may be feasible there too. Downgrade issues and a
specification are discussed in [I18Nemail-downgrade].
The first of these two options, that of rejecting or returning the
message to the sender MAY always be chosen.
There is also a third case, one in which the client is I18Nemail-
capable, the server is not, but the message does not require the
extended capabilities. In other words, both the addresses in the
envelope and the entire set of headers of the message are entirely in
ASCII (perhaps including encoded-words in the headers). In that
case, the client SHOULD send the message whether or not the server
announces the capability specified here.
5. Downgrading Before and After SMTP Transactions
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In addition to the in-transit downgrades discussed above, downgrading
may also occur before or during initial message submission or after
delivery to the final delivery MTA. Because these cases have a
different set of available information from in-transit cases, the
constraints and opportunities may be somewhat different too. These
two cases are discussed in the subsections below.
5.1. Downgrading Before or During Message Submission
Perhaps obviously, the most convenient time to convert an address or
message from internationalized to conventional ASCII form is at the
originating MUA, either before the message is sent or after the
internationalized form of the message is rejected or bounced by some
MTA in the path to the presumed destination. At that point, the user
has a full range of choices available, including contacting the
intended recipient out of band for an alternate address, consulting
appropriate directories, arranging for translation of both addresses
and message content into a different language, and so on. While it
is natural to think of message downgrading as optimally being a
fully-automated process, we should not underestimate the capabilities
of a user of at least moderate intelligence who wishes to communicate
with another such user.
In this context, one can easily imagine modifications to message
submission servers (as described in RFC 4409 [RFC4409]) so that they
would perform downgrading, or perhaps even upgrading, operations,
receiving messages with one or more of the internationalization
extensions discussed here and adapting the outgoing message, as
needed, to respond to the delivery or next-hop environment it
encounters.
5.2. Downgrading or Other Processing After Final SMTP Delivery
When an email message is received by a final delivery SMTP server, it
is usually stored in some form. Then it is retrieved by client
software via some email retrieval mechanisms such as POP, IMAP or
others.
The SMTP extension described in Section 4.1 provides protection only
in transport. It does not prevent MUAs and email retrieval
mechanisms that have not been upgraded to understand
internationalized addresses and UTF-8 headers from accessing stored
internationalized emails.
Since the final delivery SMTP server (to be more specific, its
corresponding mail storage agent) cannot safely assume that agents
accessing email storage will be always be capable of handling the
extensions proposed here, it MAY either downgrade internationalized
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emails or specially identify messages that utilize these extensions,
or both. If this is the case, the final delivery SMTP server MUST
include a mechanism to preserve the original internationalized forms
without information loss to support access by I18Nemail-aware agents.
The method and format for downgrading at the final delivery SMTP
server is [[anchor10: will be]] discussed in [I18Nemail-pop] and
[I18Nemail-imap].
[[anchor11: Note in draft: There are at least four cases. Both MUA
and IMAP/POP are compliant. Both are non compliant. And only of
them is compliant. Do we need to invent different methods for each
case?]]
6. Advice to Designers and Operators of Mail-receiving Systems
[[anchor13: Note in draft: The material that follows contains some
forward-looking, predictive, statements about discussions to occur
and documents to be written. Be sure they are true before Last
Call.]]
In addition to the protocol specification materials in this set of
documents, the working group has had extensive discussions about
operational considerations in the use of internationalized addresses.
Those topics include how such addresses should be chosen, how they
should relate to ASCII alternatives if such alternatives exist, the
management of mailing lists that might support and contain a mixture
of all-ASCII and non-ASCII addresses, and so on. Those issues are
discussed in [I18Nemail-ops] and [I18Nemail-Exploder].
7. Internationalization Considerations
This entire specification addresses issues in internationalization
and especially the boundaries between internationalization and
localization and between network protocols and client/user interface
actions.
8. Additional Issues
This section identifies issues that are not covered as part of this
set of specifications, but that will need to be considered as part of
deployment of email address and header internationalization.
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8.1. Impact on IRIs
The mailto: schema defined in [RFC2368] and discussed in IRI
[RFC3987] may need to be modified when this work is completed and
standardized.
8.2. POP and IMAP
While SMTP takes care of the transportation of messages, IMAP
[RFC3501] and POP3 [RFC1939] are among mechanisms used to handle the
retrieval of mail objects from a mail store by a client. The use of
internationalized mail addresses or UTF-8 headers will require
extensions to POP and IMAP and/or modifications to the design and
implementation of mail stores and the mechanisms that final delivery
SMTP servers use to put mail into them. However, those mechanisms
are separate from those associated with transport across the network
and are discussed only minimally in this series of documents. The
general issues, and proposed required modifications to the protocols,
are [[anchor18: will be]] covered in [I18Nemail-pop] and [I18Nemail-
imap]. Some preliminary discussion appears in in Section 5.2.
Implementation of internationalized POP and IMAP support is, of
course, not required for implementation of the transport and in-
transit header extensions specified in other documents or this set
(or vica versa).
9. IANA Considerations
This overview description and framework document does not contemplate
any IANA registrations or other actions. Some of the documents in
the group have their own IANA considerations sections and
requirements.
10. Security Considerations
Any expansion of permitted characters and encoding forms in email
addresses raises some risks. There have been discussions on so
called "IDN-spoofing" or "IDN homograph attacks". These attacks
allow an attacker (or "phisher") to spoof the domain or URLs of
businesses. The same kind of attack is also possible on the local
part of internationalized email addresses. It should be noted that
one of the proposed fixes for, e.g., URLs, does not work for email
local parts since they are case-sensitive. That fix involves forcing
all elements that are displayed to be in lower-case and normalized.
Since email addresses are often transcribed from business cards and
notes on paper, they are subject to problems arising from confusable
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characters. These problems are somewhat reduced if the domain
associated with the mailbox is unambiguous and supports a relatively
small number of mailboxes whose names follow local system
conventions; they are increased with very large mail systems in which
users can freely select their own addresses.
The internationalization of email addresses and headers must not
leave the Internet less secure than it is that without the required
extensions. The requirements and mechanisms documented in this set
of specifications do not, in general, raise any new security issues.
They do require a review of issues associated with confusable
characters -- a topic that is being explored thoroughly elsewhere
[IDN-nextsteps] -- and, potentially, some issues with UTF-8
canonicalization, discussed in [RFC3629]. The latter is also part of
the subject of ongoing work discussed in [Net-Unicode]. Specific
issues are discussed in more detail in the other documents in this
set. However, in particular, caution should be taken that any
"downgrading" mechanism, or use of downgraded addresses, does not
inappropriately assume authenticated bindings between the
internationalized and ASCII addresses.
In addition, email addresses are used in many contexts other than
sending mail, such as for identifiers under various circumstances.
Each of those contexts will need to be evaluated, in turn, to
determine whether the use of non-ASCII forms is appropriate and what
particular issues they raise.
11. Acknowledgements
This document, and the related ones, were originally derived from
drafts by John Klensin and the JET group [Klensin-emailaddr], [JET-
IMA]. The work drew inspiration from discussions on the "IMAA"
mailing list, sponsored by the Internet Mail Consortium and
especially from an early draft by Paul Hoffman and Adam Costello
[Hoffman-IMAA] that attempted to define an MUA-only solution to the
address internationalization problem. [[anchor21: Note in draft: may
want to move some of this to "history" or reference it]]
12. Change History
[[anchor23: This section to be restructured prior to publication. It
may be useful to retain parts of it to facilitate establishing dates
and documents for the history of this work.]]
This document has evolved through several titles as well as the usual
version numbers. The list below tries to trace that thread as well
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as changes within the substance of the document. The first document
of the series was posted as draft-klensin-emailaddr-i18n-00.txt in
October 2003.
12.1. draft-klensin-ima-framework: Version 00
This version supercedes draft-lee-jet-ima-00 and
draft-klensin-emailaddr-i18n-03. It represents a major rewrite and
change of architecture from the former and incorporates many ideas
and some text from the latter.
12.2. draft-klensin-ima-framework: Version 01
o Some clarifications of terminology (more to follow) and general
editorial improvements.
o Upgrades to reflect discussions during IETF 64.
o Improved treatment of downgrading before and after message
transport.
12.3. draft-ietf-eai-framework: Version 00
This version supercedes draft-klensin-ima-framework-01; its file name
should represent the form to be used until the IETF email address and
header internationalization ("EAI") work concludes.
o Changed "display name" terminology to be consistent with RFC 2822.
Also clarified some other terminology issues.
o Added a comment about the possible role of MessageSubmission
servers in downgrading.
o Removed the "IMA" terminology, converting it to either "EAI" or
prose.
o Per meeting and mailing list discussion, added conformance
statements about bouncing if neither forwarding nor downgrading
were possible and about implementation requirements.
o Updated several references. Some documents are still tentative.
o Fixed many typographical errors.
13. References
13.1. Normative References
[ASCII] American National Standards Institute (formerly United
States of America Standards Institute), "USA Code for
Information Interchange", ANSI X3.4-1968, 1968.
ANSI X3.4-1968 has been replaced by newer versions with
slight modifications, but the 1968 version remains
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definitive for the Internet.
[I18Nemail-Exploder]
"Placeholder: whatever we call the mailing list document",
2005.
This document is expected to be developed by the WG. The
date given here is purely arbitrary.
[I18Nemail-SMTPext]
Yao, J., Ed. and X. Lee, Ed., "SMTP extension for
internationalized email address", draft-yao-smtpext-01
(work in progress), January 2006.
The next version of this document will appear as
draft-ietf-eai-smtpext-00.txt.
[I18Nemail-UTF8]
Yeh, J., "Transmission of Email Headers in UTF-8
Encoding", draft-yeh-ima-utf8headers-00 (work in
progress), October 2005.
The next version of this document will appear as
draft-ietf-eai-utf8headers-00.txt.
[I18Nemail-downgrade]
YONEYA, Y., Ed. and K. Fujiwara, Ed., "Downgrading
mechanism for Internationalized eMail Address (IMA)",
draft-yoneya-ima-downgrade-00 (work in progress),
October 2005.
The next version of this document will appear as
draft-ietf-eai-downgrade-00.txt.
[RFC1651] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extensions", RFC 1651, July 1994.
[RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extension for 8bit-MIMEtransport",
RFC 1652, July 1994.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels'", RFC 2119, March 1997.
[RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
April 2001.
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
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"Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
13.2. Informative References
[Hoffman-IMAA]
Hoffman, P. and A. Costello, "Internationalizing Mail
Addresses in Applications (IMAA)", draft-hoffman-imaa-03
(work in progress), October 2003.
[I18Nemail-constraints]
Klensin, J., "Internationalization in Internet
Applications: Issues, Tradeoffs, and Email Addresses",
February 2006.
[I18Nemail-history]
Klensin, J., "Decisions and Alternatives for
Internationalization of Email Addresses", April 2006.
This document is expected to be developed by the WG. The
date given here is purely arbitrary.
[I18Nemail-imap]
Klensin, J., "Considerations for IMAP in Conjunction with
Email Address Internationalization", June 2006.
This document is expected to be developed by the WG. The
date and authorship given here are purely arbitrary.
[I18Nemail-ops]
"Placeholder: whatever we call the operations document",
2005.
This document is expected to be developed by the WG. The
date given here is purely arbitrary.
[I18Nemail-pop]
Newman, C., ""POP3 Support for UTF-8", February 2006, <htt
p://www.ietf.org/internet-drafts/
draft-newman-ima-pop-00.txt>.
The next version of this document will appear as
draft-ietf-eai-pop-00.txt.
[IDN-nextsteps]
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Klensin, J. and P. Faltstrom, "Review and Recommendations
for Internationalized Domain Names (IDN)", April 2006, <ht
tp://www.ietf.org/internet-drafts/
draft-iab-idn-nextsteps-05.txt>.
[JET-IMA] Yao, J. and J. Yeh, "Internationalized eMail Address
(IMA)", draft-lee-jet-ima-00 (work in progress),
June 2005.
[Klensin-emailaddr]
Klensin, J., "Internationalization of Email Addresses",
draft-klensin-emailaddr-i18n-03 (work in progress),
July 2005.
[Net-Unicode]
Klensin, J. and M. Padlipsky, "Unicode Format for Network
Interchange", April 2006, <http://www.ietf.org/
internet-drafts/draft-klensin-net-utf8-00.txt>.
[RFC1939] Myers, J. and M. Rose, "Post Office Protocol - Version 3",
STD 53, RFC 1939, May 1996.
[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.
[RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded
Word Extensions: Character Sets, Languages, and
Continuations", RFC 2231, November 1997.
[RFC2368] Hoffman, P., Masinter, L., and J. Zawinski, "The mailto
URL scheme", RFC 2368, July 1998.
[RFC2449] Gellens, R., Newman, C., and L. Lundblade, "POP3 Extension
Mechanism", RFC 2449, November 1998.
[RFC2822] Resnick, P., "Internet Message Format", RFC 2822,
April 2001.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, January 2005.
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[RFC4409] Gellens, R. and J. Klensin, "Message Submission for Mail",
RFC 4409, April 2006.
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Authors' Addresses
John C Klensin
1770 Massachusetts Ave, #322
Cambridge, MA 02140
USA
Phone: +1 617 491 5735
Email: john-ietf@jck.com
YangWoo Ko
MOCOCO, Inc.
996-1, 11F, Mirae Asset Venture Tower, Daechi-dong
Gangnam-gu, Seoul 135-280
Korea
Email: yw@mrko.pe.kr
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Klensin & Ko Expires November 25, 2006 [Page 19]
