We ship with FedEx, UPS and DHL, so we are generally unable to deliver to US Postal Boxes.
FedEx does offer SmartPost where they will hand off your package to the Postal Service.
If you select this option, please note that your FedEx tracking information will not be updated once they've handed it over to the post office.
If you haven't received your package within 10 business days you'll want to contact your local post office directly for more information.