Under fire from the Newspaper Association of America and even some local mailers, the U.S. Postal Service shelved plans last month to launch its Auto Day program. The program encourages automobile companies to send out bulk mailings to arrive on Fridays. It was blasted by the association, which charged that the USPS was unfairly using its governmental status to lure advertisers away from newspapers. Postmaster General William J. Henderson said the agency would abandon the program, which had been in its test phase in Milwaukee.