Are your letters and packages ready to mail so your loved ones will receive them by Christmas? The USPS recommends sending Military First-Class and Priority Mail no later than Dec. 9, and Military Priority Express Mail by Dec. 16. For the contiguous U.S. (excluding Alaska and Hawaii), USPS Ground Advantage and First-Class Mail should be sent by Dec. 18, Priority Mail by Dec. 19, and Priority Mail Express by Dec. 21. Check usps.com for information on other destinations. Double-check addresses, and shake boxes to ensure they are well packed.