Delivered Duty Unpaid (DDU) is a shipping term that means the buyer is responsible for paying any taxes, duties or import fees on the shipment.
When a DDU shipment is sent, the recipient will be contacted for payment when the item reaches customs in the destination country. If the recipient refuses to pay the import fees, the item will be returned to the sender. The recipient must pay any applicable duties and taxes for the item to be released from customs and delivered.
You need to ensure that your customers are aware that they are responsible for paying the Duties and Taxes where applicable.