Thanks for the chance at this dlc cg!

Hey CG,
since you're looking for a way to block autojoiners... I guess this is the perfect old GA to tell you: Today a friend made me aware of a steam group... after googling I've learned that it's the steam group for users of a certain browser extension on the official chrome web store called "AutoJoin for SteamGifts" by someone called Geku. The extension has more than 17 thousand users. I'm sure there's the same or similar extensions for firefox and the like.
Anyways, by following the method described on stackoverflow you should easily be able to block all these people from using steamgifts.
Regards