In a small bowl combine the cranberry sauce, syrup, vinegar, and mustard. Set aside 1 cup of mixture for sauce.
Line a shallow roasting pan with foil. Place ham on a rack in prepared pan. Cover and bake at 325 for 1 hour. Baste with some of the remaining cranberry mixture; bake 35-45 minutes longer or until a meat thermometer reads 140; basting with additional mixture every 10 minutes. Heat reserved sauce; serve with ham.