As a service to customers, the post office has set up a free service that you can use when moving to change your address.  By filling out one card, the post office will provide your new address to any mailers who asks- including those who send junk mailers.  While this is good to get your bills and financial statements transferred over, it will also transfer over all of your junk mail.  There has been one junk mailer that was able to track Mr. Thrifty through a half dozen moves over 10 years.  Impressive.

Your option here is to not fill out the change of address card.  The downside is that if you don’t fill it out you will need to directly contact all of your billers, account statements, friends, subscriptions etc. and let them know of your new address.  Otherwise your mail will be marked “No Such Addressee” and returned to sender.  This is a real pain but you need to decide if it is worth it to reduce your junk mail.