I need a copy of the receipt of an iPhone I bought as a gift

I bought an iPhone last year, as a gift in the Apple Store at the Brickell Shopping Mall.

And now we need a copy of that receipt. How do I get it?

Is there a support e-mail address that I can write to? I have the phone's serial number, but I don't know who should I contact. And I am out of the States right now.

Thank you!