Great first post from needlegrrl, A good handwritten letter is a creative act celebrating April as (US) National Letter Writing Month.
Also see hippybear's Metatalk thread April Showers Bring May Flowers about posting "simply happy, joyous, silly, or positive posts" this month. (Also open to discussion for a May posting theme.)
Anyway the seams between the plastic sheets sometimes intercepted the corner of an envelope. In a building as tall as the WTC mail would hit impressive speeds. So one jammed letter would quickly gather many letters, traveling near the speed of sound, into a densely packed arterial blockage ... Guess who found them?
Splunge recounts his adventures as an "ex-officio mail plumber" valiantly clearing clogs in the WTC mail chutes in Ragini's fun post, The mail chutes of New York City