Post Offices in Upper Marlboro, Maryland, United States SearchSearch SearchSearch View: Grid 1View: Grid 2View: Grid 3View: Grid 4View: Grid 5View: List Kettering Post Office No Reviews Favorite Phone: (301) 249-4036Retail Hours Largo Post Office No Reviews Favorite Fax: (301) 925-9078Phone: (301) 925-1485Retail Hours Upper Marlboro Post Office No Reviews Favorite Fax: (301) 627-0021Phone: (301) 780-3427Retail Hours