It is incredibly rare for a shipment to be returned to sender, however it is possible and generally happens at the first stage of x raying and scanning at the courier's facilities. This may be in the origin country or the next country, not necessarily the destination country.
The main reasons for this may be:
Prohibited items
Insufficient packaging
Damage to the shipment or packaging
An issue with the delivery address or recipient
Failure to pay duties and taxes if required
If the courier or customs authority deems it necessary to return your shipment, it will be returned to the original address it was collected from.
Please remember that if prohibited items are found in your shipment, the courier and/or customs authority has the right to dispose of the entire shipment. In the majority of cases, the affected box/bag will be returned to sender but this is not a guarantee. Please ensure you have read through the prohibited items list on our website prior to shipping your goods.