Hi, I used a USPS provided medium flat rate box for a combined order. The weight was low due to small light items. I am now being charged a fee for underpayment on a flat rate USPS box? I changed it to a medium flat rate box on the order, from a smaller box. Cost was $19.98 with eBay shipping. I've sent several medium flat rate box and the shipping was the same $19.98 eBay rate. If it's a flat rate it cost the same for 1 lb. or 10 lb. It weighed about 5 lb. max. How does the charge on a flat rat...

USPS medium flat rate box | Ask a Mentor

USPS medium flat rate box | Ask a Mentor | eBay Community