4Seller Supports Connect Royal Mail V3 (Royal Mail UK)to fulfill orders easily. 

Note: Royal Mail V3 is authorized to 4Seller through EASYPOST.

Step 1: Setting--Order & Shipping--Major Parcel Carriers--Royal Mail OBA

Step 2: Setting custom name--Fill required Info--Connect 

Step 3: After Authorizing pls check in the "Authorized Logistics Provider"

Any problems pls contact 4Seller Support Team: support@4seller.com