BTSSB: Shopping Cart priority?

I ordered from BTSSB for the very first time this Tuesday. As I've never done it before, I decided to go with what seemed the safe method and ordered by email, as that is the method I found a great guide in english to. I'm still waiting for my confirmation email, and I'm starting to worry.. What if somebody else ordered by shoppping cart, and the dress I wanted is all sold out when they finally get to my email, Since the shopping cart system gets you a confirmation email instantly? Does this happen?