[recipient list trimmed; this has nothing to do with idn, and is too
narrow for IETF, and Dan's mailer complains if you cc him anyway.]
using raw utf-8 in message headers wouldn't replace 2047. instead,
it would add yet another format that MUAs are expected to parse
and display. it would not reduce complexity, it would add to it.
If we add new MIME headers and ESMTP commands, MUA and MTA should be able to
have a smooth transition from 7bit encoded 8bits to UTF8.
I don't think that's the right way to go - first, because SMTP MTAs have
no idea about whether the MUA can support raw utf-8 (this was the mistake
we made with 8BITMIME, let's not repeat it); second, because expecting
MTAs to extensively rewrite messages is a good way to introduce errors;
third, because this pretends that a good part of the problem can be
solved by changes to the MTAs, when in reality the UA issues are a far
If there is a requirement of change anyway, why not change it to
something that is more simple and well support by the Unicode Consortium.
It's simply not the case that raw utf-8 in headers is simpler to deal
with than the current method of encoding things in ASCII. There are
complexities associated with each, but the UTF-8 complexities are new
ones whereas the ASCII ones are already familiar. In some ways we'd be
far better off if we kept structured fields in ASCII - even though that