The Museum of Modern Art in NY is currently exhibiting a collection of envelopes which constitute a work of art by Alighiero Boetti, perhaps the most prominent Italian conceptual artist of the 20th century. Wikipedia describes this important piece: Dossier Postale (1969–70) consists of a series of letters which were sent to 26 well-known recipients, primarily artists, art critics, dealers, and collectors active at the time. Boetti sent the envelopes to imaginary addresses, thus each letter was returned to the artist undelivered, demonstrating Boetti’s preoccupation with improbability and chance. The envelopes, complete with colored stamps and stray markings from the postal service, make an interesting assortment of lines and colors: Marcel Duchamp had been dead for a year when Boetti mailed him this letter Talented illustrator Bill Mayer also has a marvelous collection of decorated envelopes. He has not, to my knowledge, exhibited them at the Museum of Modern Art, but ...