How do I get someone to verify that they've received a game they've won?

You know, one of the things I hate is when I have a GA and they prize gets sent out, cashed out and the winner doesn't verify that they've won on steamgifts. There's a Russian person thatshallremainanonymousinthisdiscussion and he won a game from me, redeemed the key and he has yet to verify that he received it on my prize page here on steamgifts. I sent him a very polite email and comment I even used a simple and also polite Russian translation and he basically told me to f-off.

I know it's not a big deal, but it kinda is disrespectful and I kinda need that confirmation. How do I get the confirm?