Large number of emails send usually for commercial purposes are called mass emails. There are two different types of such messages basing on legal issues. One of which are legal and are called mass emails and the other one, illegal, is called spam. Those bulk emails are mainly used by companies for their commercials. Especially for their features that make them very cheap and effective with a good feedback on different elements of the campaign. For example, you can test which, out of many, head lines is the best. This test is based on application attached to the message that sends an information about actions of a recipient on this message. Mass emails are send only to people who have subscribed on a website. A lot of companies run sign up or a subscribe forms on their websites to gain more customers use their services or buy products. Such lists also can be obtained from an online distributer. But depending on how many contacts you would like to have you may pay more.