Well, I should have read these reviews before doing an exchange with Cardpool.
I sent in a restaurant gift card two weeks ago using Cardpool's own pre-printed mailing label. I included the packing slip I printed from their site which had my name, address, and transaction number.
I wrote them asking where my Amazon gift card was and, surprise, surprise, they supposedly have somehow never received my gift card. How do you prove you mailed something? You can't. So, I'm sol.
They discovered a great way to scam people. Stay far, far, far away!