Effective July 14, 2024, USPS® will engage in enhanced post-acceptance examination efforts to enforce customs declaration form requirements for mail sent to or from addresses at any overseas Military Post Office (MPO). This includes any Army Post Office (APO) for the U.S. Army or U.S. Air Force, any Fleet Post Office (FPO) for the U.S. Navy or U.S. Marine Corps, and to or from addresses at any Diplomatic Post Office (DPO), in accordance with Mailing Standards of the United States Postal Service, Domestic Mail Manual (DMM) (sections 608.2.4.4 and 703.2.3.6 through 703.2.3.8).
Mail sent between these locations that weighs 16 ounces or more (regardless of contents, value, shape, or mail class) or that contains a good (regardless of weight, shape, or mail class) must bear a properly completed, computer-generated customs declaration form. Additionally, data associated with the customs form must be electronically transmitted to USPS using USPS-approved software.
Except for certain mail under existing exemptions specified in DMM section 703.2.3.9, overseas APO, FPO, and DPO mail that is not in compliance with these customs requirements will be returned to sender beginning July 14, 2024. Any changes to the exemptions specified in DMM 703.2.3.9 will be set forth in a final rule to be published later.
—Trade Policy and Process,
International Processing Operations, 6-13-24