 If someone wants to send you holiday gifts and cards, have them ship early to arrive by Christmas. On a ship or overseas, the priority mail deadline is December 11th, but for zip codes starting with 093, it's December 9th. The Express Mail deadline is December 18th, except for zip codes 093, where Express Mail service is not available. Get information on wait limits and restrictions and all the shipping deadlines online or at your local military post office.