Mailing lists can be a very effective form of marketing for your business. Make sure you only use an "opt-in" method of marketing to your customers. Email lists can be comprised of people who sign up at your Web site, but do not simply add people to your list without their permission or you will simply become another spammer. When you send people information whether it be email or real-mail, you must make sure they want to receive your information or you will not only waste your time and money but you will also offend people and your mailing campaign will backfire on you and actually hurt your business.