[Nmh-workers] Handling non-ASCII

[Ken Hornstein]

Nmh got a bug report recently complaining that a message containing a binary
subject was displayed on a user's terminal and messed it up.

The user was kind enough to include the original message; the issue was
that the message was spam and in UTF-8, but wasn't using RFC-2047 encoding.
Actually the message was in UTF-8 but didn't contain any MIME character set
marking at all (the actual subject line used characters close to regular
characters in what I assume was an attempt to evade normal spam filter
rules, e.g.: ṼĮÂġṚа).

So of course this is mega-bogus, but the bug reporter made the point
that nmh should deal better, and I have to agree it kinda sucked
on that one.  Obviously if there is no character set the default
should be us-ascii, but what should we do if the text is outside
of us-ascii?  The original bug reporter hardcoded a test for isprint()
in scan, but that seems wrong to me (especially if your scan format
used rfc2047 decoding).  So does anyone have any suggestions as to what
the right answer should be?

--Ken