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Email Address Internationalization

Document Charter Email Address Internationalization WG (eai)
Title Email Address Internationalization
Last updated 2006-03-02
State Approved
WG State Concluded
IESG Responsible AD Pete Resnick
Charter edit AD (None)
Send notices to (None)


The email address has two parts, local part and domain part.
Email address internationalization must deal with both. This
working group's previous experimental efforts investigated the
use of UTF-8 as a general approach to email
internationalization. That approach is based on the use of an
SMTP extension to enable the use of UTF-8 in envelope address
local-parts, optionally in address domain-parts, and in mail
headers. The mail header contexts can include both addresses
and wherever existing protocols (e.g., RFC 2231) permit the use
of encoded-words.

All WG deliverables specified under the original charter,
particularly the experimental protocol specifications, have
been completed. The core specifications have been implemented
and interoperability tests performed. The WG is now being
rechartered to permit advancing revised versions of those
specifications and supporting documents into the standards

As a result of implementation and testing experience, the WG
has concluded to drop the model of in-transit
downgrading that was a key part of the original effort.
In-transit downgrading approaches simply do not work well
enough and predictably enough to be worth the considerable
additional complexity that accompanies them. In particular,
dropping in-transit downgrading eliminates the need for the
first significant change to the syntax of an email address
since RFC 821 and 822 were published in 1982.

Work will therefore reflect a "no fallback" approach. That
approach provides a very minimal transition mechanism, but is
consistent with the long-term view that email with invalid
addresses or syntax should be rejected, rather than fixed up in
transit between submission servers and delivery servers.
Discoverable fallback addresses that could be applied before or
during message submission or after SMTP "final delivery" may be
investigated. The WG may also develop other materials to give
advice to implementers or operators. Those efforts may lead to
informational documents or best practices recommendations, but
are considered independent of the core documents. Work on them
will progress only under the condition that it not delay the
primary standards track specifications.

The WG believes that the lessons learned from implementation
and testing and removal of in-transit downgrading as a goal
eliminates all major areas of controversy about the core
specifications and should permit very rapid progress. Such
rapid progress is an explicit goal for the WG; issues resolved
in the past will not be revisited unless those who wish to do
so can demonstrate data, reasoning, or consequences that were
not considered earlier. At the same time, any attempt to
significantly extend an established and widely deployed set of
protocols may uncover new consequences or side effects that
need consideration and evaluation. If faced with a choice
between spending time on such new considerations, the WG will
favor getting things right over accelerating the schedule.


The following deliverables are foreseen in this charter. The WG
chairs may (re)structure the deliverables into specific
documents or document sets as needed. Adding or removing
documents other than those listed below as "Required" or
"Additional" will require a charter update.

Required Documents (these are the "core specifications"
referred to elsewhere)

  • Overview and Framework for Internationalized
    Email, replacing RFC 4952 (Informational or Proposed
    Standard at IESG discretion once complete)

  • UTF-8 SMTP extension specification, replacing RFC 5336
    (Proposed Standard)

  • Header format specification, replacing RFC 5335 (Proposed

  • Internationalized DSN specification, replacing RFC 5337
    (Proposed Standard)

  • UTF-8 POP specification, replacing RFC 5721 (Proposed

  • UTF-8 IMAP specification, replacing RFC 5738 (Proposed

Additional possible documents suggested. While milestones are
listed for most of these documents, they may be dropped by the
WG with the consent of the Responsible AD.

  • Advice for MUA implementors (Informational or BCP)

  • Advice for EAI deployment (Informational or BCP)

  • Advice for non-ASCII and ASCII addresses for the same mailbox
    (Informational or BCP)

  • Mailinglist (Informational or Standards Track, replacing

  • Mailto (Proposed Standard, updating draft-duerst-mailto-bis
    to reflect internationalized addresses)

  • Protocol extensions for RFC 4409 Submission Servers or
    configuration advice for the MUA->Submission server interface.