Using a PO box as a delivery address is generally possible, but not all postal companies (or local departments) are able to deliver to PO box addresses. Therefore, there is a chance we have to ask you for an alternative address. To be sure, we advise you to fill in a physical address.
Have you already ordered and want to change the delivery address? This is only possible as long as your order has not yet been sent. For further details, please see How can I change my delivery address?