There are a few reasons an order can be returned to sender but most often it is due to an undeliverable address. Other instances include the package being unclaimed at customs or refused/returned by your end customer. You will receive notice once the order arrives back to our facility. We would advise contacting your end customer to determine how they would like to proceed and contact us with an updated address if you wish to have the product reshipped. New shipping charges will be applied for orders that have been unclaimed at customs, returned by your customer, or had an incorrect address originally provided.