Opt in email list is one of the most important tool for the advertisers who are using email marketing for promoting their website. The opt in email list helps them to identify their target consumers and reach out to them. This list is collected by the online media company through various means like online surveys, forms, co-registration etc. It consist of people who have agreed to receive information related to a product of their interest in the form of email, newsletter etc. So if the advertiser needs to promote his website to people who are likely to visit his site then he can buy opt in email list. It allows him to make his marketing campaign more successful and effective. He can use email marketing and send the emails to the opt in email list so that the target clients can also get the relevant information. They would be willing to visit the website and the advertiser can then turn the traffic into consumers and get good profits. Thus the opt in email list is very useful for the advertisers. It is considered to be better than sending emails randomly to people who may not even be interested in your product. Random email marketing affects the cost also and therefore should be avoided.