I know that when I pay for something online, I want the merchant to know my email address -- I'm expecting a receipt, shipping confirmation, etc. You may consi

I know that when I pay for something online, I want the merchant to know my email address -- I'm expecting a receipt, shipping confirmation, etc. You may consider using help text to indicate that they'll receive an order confirmation at the email address they provide, just in case they may not immediately realize why your asking for it.