How to identify a Deliver to Post Office shipment in your Create Shipment request
The web service called Create Shipment is where you specify all the details about your shopper’s parcel, including identifying it as a Deliver to Post Office shipment. If you use non-contract shipping, use the Create Non-Contract Shipment web service instead.
Create Shipment includes request elements specifically related to Deliver to Post Office, which are listed and described in detail below. For the full list of fields required for a Create Shipment request, refer to Contract Shipping or Non-Contract Shipping documentation.