We also update the shipping method if:
- The order has a mapped shipping service
- The carrier, service, and package used matches the shipping service mapping
These settings are necessary, because Volusion's system requires that we send back the shipping method ID, instead of the actual carrier, service and package text. Because of Volusion's unique way of receiving the shipping method, we must return an ID that is valid within the Volusion system.
For example, you can click on the green configured service link to see what the carrier, service, and package is mapped to for the order:
In this case, the order is set to USPS Priority Mail, Package:
However, this differs from the service type that is actually on the order, which is Priority Mail Express.
If the carrier, service, or package don't match what is mapped, then ShipStation cannot post the shipping method accurately back to Volusion.