Logged In: YES 
user_id=29957

No, look - it's not a matter of "what charset to use". It's
simply a matter of
_leaving_ _it_ _alone_ unless you actually need to do
something about it.

_Don't_ gratuitously use RFC2231 encoding. There is no
point. Use the format
that the user sent the message in - that's the only
guarantee you have about the
user's MUA capabilities. 

_IF_ the message is entered with a subject that is outside
the ASCII range, 
_then_ use encoding. Otherwise, Leave It Alone.