Amazon Services
Amazon Marketplace Web Service (Amazon MWS) Documentation
Amazon MWS Documentation

Step 5 - Use an Amazon-partnered carrier for your inbound shipments (optional)

Sellers in the EU region (the France, Germany, Italy, Spain, and UK marketplaces) and the US marketplace can take advantage of discounted shipping rates by using an Amazon-partnered carrier for their inbound shipments.

For more information, see Using an Amazon-partnered carrier for your inbound shipment.