Do I have to give a deposit back?

um sorry dude, you’re wrong. if the guy asks for his money back, and this dude says no, it is theft by deception… as where the man that gave the deposit was never informed it was non-refundable, therefore he was deceived in the fact that unless otherwise stated in a contractual agreement that his money was not to be refunded which is the LAW if you want to keep the deposit, he is legally entitled to his money.

and because he did use USPS for the monetary transaction, it is a case on the federal level, REGARDLESS of the amount of money. sorry once again.