Mail Us Your Mail Art for the First Annual MAIL ART Show Gallery 11x14 September 1-30, 2007 Mail Art is any art that, with proper postage, is sent via the USPS. It can be a collaged postcard, a decorated envelope or a painted package. Mail Art can also be an actual piece of art with proper postage affixed to it. CHECK WITH USPS FOR MAILING RULES AND REGULATIONS. (you can google "maby manymanos - Mail Art Calls