Interesting. The customer service rep told me, "... customers can use international credit cards to make purchases through a Square merchant’s Online Store, but the order must be placed in the U.S. and shipped to a U.S. address."

I was not aware that the ZenCart payment module sends the shipping address with the payment info, but maybe it does? Have others been able to process payments to customers with shipping addresses outside the US?

I did write back to try to clarify where they consider the order to have been "placed" - at my location in the US or at the location where the customer is typing into a browser screen. Seems unclear to me.