The barcode helps sort tubs and trays of mail as it travels around from sorting plant to local post office. Step 2: Locate the florescent yellow or orange barcode on the ballot envelope.To locate an US Postal Inspection Service office, enter a city and state abbreviation or ZIP Code (Example, Seattle WA or 98111). Once your data has been approved, the QR code will change from orange to green. Keep the browser session open and do not close the application.