For a nifty way to trace who shares / trades / resells your mailing information when you subscribe to junk catalogs, append the name of that catalog to your last name, or just the word "junk". Then you know when you get other junk where it came from. Remember to "opt out" of any catalogs you do not really need to save paper, and also stop (hopefully) from your mailing information from being sold more and more.

Fe, "John Smith delljunk"