For a list of participating retail locations, visit blue.usps.gov/purchase/voyager/blue/index.htm. Look for “Preferred Fueling Network locations” or the “PFN Location List.” The Postal Service will continuously update this site as more participants and locations join the network. If you have questions or know of locations interested in joining the PFN, send an email to the Transportation Services CMC at FuelFleetVendors@usps.gov.