I just spoke to a fellow with a very interesting email proxy system
that unfortunately works by using such 'ed cruft in subject fields.
I suppressed my gag reflex, because I understood why he was doing it.
Most current MUA's hide all headers except a specific few, so if you
want to communicate anything to the end user, the only way you have
to do it is by scribbling on those few visible fields. Or in the
body, which is even worse. Gone are the days when you could add a
header and expect anyone to see it. So, list processors aside, I
think we're going to see more of this and not less.
My MUA ignores such text when doing subject comparisons.
are all considered equal. A further step that would probably be
interesting would be to simply remove such strings from subjects
displayed in message lists.
Could this be generalized as a recommendation to MUA's? I dunno. It
seems like a feature that's useful a lot of the time, and harmful
occasionally (eg, when there is real information inside 's for some
I personally wouldn't be opposed to amending 2822 to declare that 
are comment indicators in subject fields. I know that sins against
the holy writ, but oh well...
Where are we going, and why are we in this handbasket?