The contact owns a 2019 Ford F-250. The contact stated while the vehicle was stationary at the post office, the transmission independently shifted out of park and the vehicle rolled backwards into a mailbox. The contact stated that the parking brake was not activated at the time of the failure. The contact stated no one was injured nor sought medical attention. The contact called the police department but a police report was not filed. The contact took the vehicle to the local dealer however, the mechanic was not able to duplicate the failure. Upon investigation, the contact associated the failure with NHTSA Campaign Number: 18V802000 (Power Train) however, the VIN was not included. The manufacturer had not been informed of the failure. The failure mileage was approximately 31,000.