1. Mailchimp: Known for its user-friendly interface and robust features, Mailchimp is suitable for businesses of all sizes. 2. Constant Contact: This ESP is ideal for small businesses and offers excellent customer support and a variety of templates. 3. Sendinblue: Offers a range of features including SMS marketing, making it a versatile choice for multi-channel campaigns. 4. AWeber: Known for its automation and segmentation capabilities, AWeber is great for businesses looking to personalize their marketing efforts. 5. GetResponse: This ESP offers advanced analytics and a powerful drag-and-drop editor for creating professional emails.