Ah okay, so the Post Office's message wasn't really responding to anything my website is doing. Naturally.
I posted so many times above, the one remaining minor issue got a little buried. In case you missed it...
I've just carried an order all the way through to PayPal successfully. However, one more minor issue has come up. On the "Review Order" screen, the message "You must select a shipping option before continuing" was at the top of the screen--in spite of my having already selected a shipping option which was calculated into the order just fine.
Joined: 01/11/2008