EDDM - Every Door Direct Mail is a product delvelope by th US Post Office. It is designed to allow small business owners the ability to simply have cards (To USPS Flats (not letter class)  Specifications  delivered to every home in a zip code or carrier route. Then utilizing the USPS website (www.usps.eddm.gov) you can select the area you want to go, print some paperwork and then bundle the cards with a slip on the front of each bundle...and take to your local post office and pay. YOu do not need a permit for EDDM retail.