The aim of this paper was to investigate e-mail marketing and its role in successful online communication. E-mail marketing is a key tool in online communication, enabling personalized and direct access to users. There are numerous advantages of its use, considering that it enables companies to send target messages to a specific audience, which increases the relevance of the content and the engagement of the recipient. By using segmentation and customized campaigns, email marketing can effectively reach potential and existing customers. Personalization is key to the success of email campaigns. Customized content and offers based on user interests and behavior significantly improve email open rates. Automation further improves efficiency by sending timely and relevant messages, reducing operational costs and enabling focus on strategic tasks. Monitoring and analyzing the performance of campaigns provides valuable insights, enabling the optimization of future campaigns. Analytics tools make it possible to understand user behavior, identify successful tactics and areas for improvement. Examples of successful campaigns, such as Airbnb, Animot and ASOS, were analyzed in the paper, where the importance of personalization and content relevance was shown. Newsletters, like Netflix and Duolingo, keep users interested through continuous notifications. Email marketing, integrated into the marketing strategy, improves communication and achieves marketing goals.