Actually, the reason that you get all those preapproved credit cards is because the card company's actually get the information directly from the credit agencies. The reason I know this is because I'm getting a crap load of crap deleted and I "opted-out" of these so called "pre-screenings". If you want to opt out I am posting a paragraph from Transunion Credit Agencies' website. They also gave me this number over the phone. It's as follows:
Opt-Out Contact Information
TransUnion wants to help companies give American consumers the choices they want. This choice includes the right to say, "No, thank you" to their offers. If you want your name and address removed from mailing lists obtained from the main consumer credit reporting agencies — TransUnion, Experian, Equifax, and Innovis — call 888-5OPTOUT (888-567-8688), or write to the following address:
TransUnion LLC's Name Removal Option
P.O. Box 97328
Jackson, MS 39288-7328
Include the following information with your request:
First, middle, and last names (including Jr., Sr., III)
Current address
Previous address (if you've moved in the last six months)
Social Security number
Date of birth
Signature
Good luck.. I hope this helps!