Bulk mail forms for non-profits and for-profit businesses can be found on the USPS website. If you are mailing Standard Class, you can find the forms you need (including the 3602-EZ form) here. For First Class or Priority Mail, your forms are here. Your business mail entry unit (BMEU) postal staff should be able to help you with paperwork as well. If you don’t want to go through the hassle of filling out your own forms, use a mail house like PostcardMania to do it for you.