> If there is a standard notation for numbering, and discussions in e-mail
> are tagged appropriately (e.g. on the subject line), then automatic
> e-mail filters can maintain the archives.

But there isn't. ;-p (though gnats could be used for it)
IMHO, it's worth to think about what we can do right now
rather than what we should do in the perfect world...
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Izumi Tsutsui