> IETF headers  are a  religious issue.  The very  concept of  changing the
> subject line would violate the religious foundation on which IETF headers
> are built ("Thou shalt not change the headers except to add a Message-ID:
> if the message cometh from a sinful  MUA that doth not provde one, to add
> a Received: line with thine own host  name and, if such is thy desire, to
> add a Sender: pointing to the owner-xxx address").
 
I'm not religious about headers, but I find IETF headers to be useful
in some circumstances.  For example, we have a listmaster list with
all our LISTSERV administrators on it.  List owners vcan send
questions to it.  With IETF headers, I can tell that a reply was
sent to someone who asked a question and cced to the list.
With regular headers it's not obvious.