Mailster

Mailster has been the longest-running all-in-one WordPress email plugin for over a decade. It includes a visual drag-and-drop editor, an extensive template library, subscriber segmentation, autoresponders, and the ability to automatically send new posts to subscribers. The plugin handles list management, email delivery, bounce handling, and detailed open/click tracking from within WordPress.

It works well for newsletter publishers who want email built directly into WordPress without learning a new platform. The plugin is self-hosted on your server, so you keep full control of subscriber data and can use any SMTP provider you prefer. Mailster's strength is simplicity and deep WordPress integration, though it doesn't include SMS or advanced behavioral marketing features like newer platforms do.