Re: [idn] I-D ACTION:draft-ietf-idn-uri-00.txt

["D. J. Bernstein" <djb@cr.yp.to>]

The general question here is ``What will happen if we start using IDNs
before we do the software upgrades necessary to make IDNs work?''

UTF-8 IDNs will cause trouble in this case. The point I'm making is that
ACE IDNs will cause trouble too.

UTF-8 IDNs will lead to additional non-821-compliant addresses in SMTP
and additional non-822-compliant addresses in message header fields. The
resulting 8-bit addresses are known to cause trouble for some programs.

ACE IDNs will lead to additional non-821-compliant addresses in SMTP and
additional non-822-compliant addresses in message header fields. The
resulting long addresses are known to cause trouble for some programs.

Maynard Kang writes:
> If you use UTF-8 (or any 8-bit CES) in e-mail addresses, SMTP servers which
> adhere strictly to RFC 821 will blow up due to the US-ASCII restriction. If
> you use ACE, perhaps only your mailing list software will blow up.

My software doesn't have any trouble. Please learn to read. What matters
is that it effectively lowers any limits that your software might place
on address length.

> I think there are more systems which deal with SMTP than with mailing lists.

ezmlm and its variants send a huge amount of mail every day. Keep in
mind that (1) qmail is running on a very active 10% of the Internet's
SMTP servers and (2) automatic bounce handling, via these long return
addresses, is one of the top ten reasons that people install qmail.

> problems at lower layers tend to affect a greater number of systems

It would help to skip the ``layer'' commentary and focus on the effects.
The effects are what users care about.

---Dan