It's important to make sure all labels are printed in 4x6 size format. To make your life easier, we highly recommend switching to thermal labels. Make sure the label covers the entire printing area, and that paper labels have no tape over the barcode and are legible.

Here's the deal: Thermal labels are mandatory for ShipShop US and PostNL. USPS Packaging (envelopes and boxes) must have USPS Priority Mail labels.

If you're sending something special, like a triangular prism, it won't qualify for ShipShop USA, so use USPS First Class or Priority Mail instead.