Why won the USPS First-Clas Mail service work on my store?
The USPS First-Class Mail service requires that your product weight is in ounces and that the product itself weighs less than 13 ounces. To change your store settings to ounces, go to Store> Configure> Store Settings in Auctiva Commerce administration. The Configure Store page will load. In the Locale Settings box, select “Ounces” from the Unit of Weight field. Click the Save button at the bottom of the page.
