Why does it mark a purchase order as “sent” when I click print? I'm not gonna mail them a PO!

We sure hope you don't! Here's the scenario: You call your supplier and place a phone order because their BTB website says “call for inventory”. So you speak to the supplier on the phone (while looking at your PO) to check inventory. They have everything and they literally just took your order over the phone. 

Now you click “print” as an extra way to know that you sent it to them. You don't even have to print it. Just click print and cancel. It will mark it as sent.