I used to gather up the credit card application forms for Brand A and mail them to Brand B in their prepaid envelope. I did so many times that Citi finally send

I used to gather up the credit card application forms for Brand A and mail them to Brand B in their prepaid envelope. I did so many times that Citi finally send me an intimidating letter from their fraud department asking me to stop. I didn't, of course, but they eventually phased out the prepaid envelopes altogether.