E-mail marketing is popular with companies because:

• It is extremely cheap. Compared to direct mailing or printed newsletters the costs are negligible. The advertiser does not need to pay for production, paper, printing or postage.
• It is instant, as opposed to a mailed advertisement, an e-mail arrives in a few seconds or minutes.
• It lets the advertiser “push” the message to its audience, as opposed to a website that waits for customers to come in.
• It is easy to track. An advertiser can track bounce-backs, positive or negative responses, click-throughs, rise in sales.
• Advertisers can reach substantial numbers of e-mail subscribers who have opted in (consented) to receive e-mail communications on subjects of interest to them
• It has been proven successful when well done.
• When most people switch on their computer the first thing they do is check their e-mail.
• Specific types of interaction with messages can trigger other messages to be automatically delivered.

This guide is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.