The Express Mail eagle of the U.S. Postal Service will land in Moscow by May Day under the first postal agreement between the superpowers in more than 50 years, officials say. Postmaster General Anthony Frank announced Tuesday that the Postal Service would begin Express Mail delivering business papers, packages and merchandise to the Soviet capital May 1. Packages weighing up to 44 pounds will take two to three days to reach Moscow, and the Postal Service will offer reciprocal service for Soviet businesses to send documents by Express Mail to American firms.