Email marketing is the strategy of companies or brands using email to communicate with their potential or existing customers and send them commercial messages. This strategy is used for purposes such as strengthening customer relationships, increasing brand awareness, promoting products or services, increasing sales or retaining loyal customers. Email marketing requires a permission-based approach. This means users agree and give consent to subscribe to emails. In this way, e-mails that may be perceived as spam are not sent without the permission of the users.