The purpose of email marketing is to promote a business's products or services to a group of people who have expressed an interest in receiving such information. Email marketing can be an effective way to reach out to customers and potential customers and to build relationships with them. It can be used to send newsletters, promotional offers, and other types of content to subscribers. By using email marketing, businesses can communicate with their customers in a targeted and personalized way, and can track the success of their campaigns through metrics such as open rates, click-through rates, and conversions.