We've pointed you towards the 99% Invisible podcast previously for their coverage of postage stamp designs and pneumatic tubes, but they recently had a show on the Dead Letter Office. Appropriate for the season, no?
Even more epistolary radio fun comes to us from the BBC. The Art of Correspondence may interest you. It is up on the Internet for the next month or so. Get your ears on and start the fun.
P.S. Thanks to the L.W.A. member readers who sent in these links to us!