List Building is a long-term & continuous activity. Your email address must have seen pop-ups or square boxes on websites that ask for your name & email address for sending free updates or for subscribing to the free email address newsletter. Once you put your name & email id in the box you become a subscriber to that website. When you put your name & email address in the form you are "Opting In" to receive emails from that particular site & the list is called an "Opt-in List". Your email id & name is saved in the database of the program which can send automatic emails to the whole group email address of subscribers (i.e. list) at pre-decided intervals.
There are various sites selling Opt-in leads to internet marketers. The Opt-in list may consist of 1000 people or it may contain millions of people. Higher the number of people on the list higher would be the price you need to pay for the list. Opinions differ about the effectiveness of bought-out email marketing leads email addresses but we recommend buying the lists only if you trust the site which you are buying email marketing lists & the list is targeted towards a specific group of people representing a particular niche. Let me explain this a little further. The Opt-in list created on say, for example, email address wallstreetjournal.com would consist of financial niche which would represent a group of people email addresses who are interested in financial news or topics.
Moreover, a list build on any business opportunity website would consist of a group of people interested in new business opportunities. For better results, we recommend that you should match the interest of the people with what you are promoting through your email marketing campaign. For example, the program can send email address welcome email to everyone who subscribes to the list. This program would then send another email address after say 3 days from the date the subscriber joined & so on. This program is called an "Autoresponder".