San Mateo, Calif.--E-Stamp Corp. on Monday launched a nationwide advertising campaign. It incorporates print, banner, radio, direct marketing and television, including CNBC, CNN and The Discovery Channel. The campaign, handled by ad agency Butler, Shine & Stern in Sausalito, Calif., is aimed at small businesses and will run through the first quarter. The cost of the campaign was not disclosed, but E-Stamp is allocating $82 million for all its marketing and branding efforts. E-Stamp is financially backed by companies including Microsoft Corp., Redmond, Wash., and America Online, Dulles, Va.