It’s a very well-known scam. You cash the check, then they ask you to either wire some of that money back to them as some sort of fee or buy something for them and send the item to them. So, you deposit the check, then wire some cash to them thinking that the check you just deposited will cover that. A few days later, after you already send them the money, the check will bounce and the money you send to them will come out of your own account.
You can also earn if you shop in the many retailers listed in Inbox Dollars through a Cashback program. Many of the retailers give Cashback of up to 5%. You can also earn via coupons. There are a great number of coupons available in Inbox Dollars. Some of these coupons already gives you cash back for using them. On top of that, Inbox Dollars will credit you with $0.10 for every coupon you print and redeem.