Weirdly enough, the lack of a back-order email might actually be a good sign, despite the lack of any other emails as well. Can you check to see if your card has been charged?
My card was charged. It's listed as a pending transaction but there is a hold on the money. It was like that since day one. Funny enough Google said they won't charge until they ship. Why put a hold for the full amount for 3 days?