Processing rebates

Does anybody know how you can get a job processing rebates?

My wife and I recently retired and the other day I got to thinking that a nice work-at-home job would be processing rebates. You know the type of job I mean; you send in your cash register receipt as proof of purchase, etc. to an address and get back a cheque rebate or whatever the offer was.

I sent requests to a few companies but got zilch back so I'm wondering if it is an inside job where you have to know somebody or how do you get started.

Thanks for any help.