New version of strawman for IDNAv2

Adam M. Costello idna-update.amc+0+ at
Mon Mar 2 03:34:12 CET 2009

Mark Andrews <Mark_Andrews at> wrote:

> Mail applications regularly display mail domain names.

But do they display domain names received via DNS?  I don't think so, I
think they display domain names obtained from the message header.

For RFC-2822 (and 822) messages, which require the ACE form, the display
(converted back to Unicode from the ACE) will indeed be sub-optimal in
those cases where the normalization & case-folding chose a form that's
not best for display.

But there is already an experimental extension for UTF-8 message headers
(RFC 5335).  As internationalized domain names become more widespread, I
think it's likely that RFC 5335 or something like it will be adopted and
widely implemented, and the problem will go away for mail applications.

I expect the story will be similar for other applications that display
domain names.  If that's true, the form stored in the DNS will generally
be irrelevant to what users see.


More information about the Idna-update mailing list