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               When used in a reply, the field body MAY start with the
   string "Re: " (from the Latin "res", in the matter of) followed by
   the contents of the "Subject:" field body of the original message.
   If this is done, only one instance of the literal string "Re: " ought
   to be used since use of other strings or more than one instance can
   lead to undesirable consequences.

Personnally, I don't care. I find Arpi's mails worth that small bug.
Besides, it's a MAY, not a MUST, and the part about adding another 'Re :'
doesn't even use a captalized-RFC'ized keyword.

'In-Reply-To:', OTOH, _SHOULD_ be used for threading.

cube

-- 
That's how I did it, Anton. I never saved anything
for the swim back.
Vincent/Jerome, in Gattaca.