Unlike many other companies, our product fits in a letter-size envelope, and we use standard post, which makes deliveries to a PO BOX acceptable. For Australia only: we noticed that deliveries to a PO BOX or a locker are oftenly lost. Avoid using PO BOX or Locker Box in your address, but instead use your residential address. For the USA: we noticed that FedEx Cross Border is having troubles sometimes to deliver to a PO BOX. Please, avoid using those and instead use your residential address. For orders with DPD: to some destinations you will see a DPD option during checkout, which is faster service. DPD, nor its partners, delivers to a PO BOXes, so please do not use PO BOX address if you opt for this shipping solution.