A list of email addresses that a company has gathered through previous customer contacts, Web sign-ups or other permission-based methods. In-house lists typically generate higher conversion rates than rented lists.

Building a Highly-targeted Opt in List: When Money Lies Beneath the Lists
Are you successful with your Internet business? Better yet, do you think you are successful with your online business? When most online entrepreneurs are asked with these questions, they often brush it off.