[Users] How to correctly render non-ASCII (日本語) subject lines?

[jdebert]

By the way, it appears that thunderbird is using some kind of
workaround or guessing technique to try to correctly render non-ASCII
symbols in the Subject header, and, IIRC, the From, Sender, To, etc
headers. Perhaps it's using Content-Type to guess the Subject charset.

Not too sure about alpine but ISTR that the authors had mentioned work
on such techniques as well.

mail/mailx is not consistently rendering non-ASCII subjects unless it's
UTF-8. Doubt that it uses any techniques.

All this is complicating the problem and the finding of a good solution.

Thanks again & sorry for the trouble.

jd