Why do my flight plans sometimes file through DUATs even though I haven't signed into a DUATs account?

ForeFlight Mobile uses DUATs' filing service as a backup in case Leidos is down or too busy. You can avoid this by filing ICAO flight plans, which are always filed through Leidos, rather than FAA/Domestic flight plans. For information on filing ICAO flight plans, refer to the Filing with ForeFlight Mobile guide available in-app under DOCUMENTS > CATALOG > FOREFLIGHT.