1. until the mail spec is revised (which is to say, not in the near
future) no unencoded non-ascii characters are permitted in the message
header.
They should not be seen in email. That is not to say that they will not be
seen in Netnews.
agreed that this is a separate question. the real trick is keeping the
news articles from leaking into email.
3. for other usenet message header protocol elements which need to
contain non-ascii characters (e.g. newsgroup names) usefor (or its
successor) is encouraged to investigate the suitability of using the idna
encoding.
The view of Usefor is that IDNA is not suitable.
it would be interesting to know what the problems are, especially since
IDNA or something close to it seems likely to be used in email addresses. do
we really want usefor to have to deal with 3 or 4 separate schemes for encoding
text that appears in message headers (2047 for text, IDNA for email addresses,
something else for newsgroup names?)
Keith