Via the 'net (it figures) I came across a rather interesting solution to the influx of fan mail from the great science fiction author Robert A. Heinlein, who introduced us to Michael Valentine Smith, the Stranger in a Strange Land. (And of course a myriad of other characters and stories.)
Check out his method for replying to the vast amounts of paper that flew his way. It's been posted here by Kevin Kelly on his website. Thanks, KK.