Postal

Postal is an open-source mail delivery platform that you host and manage yourself, giving you complete control over your email infrastructure. It handles both transactional and bulk email sending, includes webhook support for tracking bounces and complaints, and provides a web UI for managing email credentials and monitoring delivery.

Best for organizations with strict data privacy requirements, existing self-hosting infrastructure, or teams comfortable maintaining their own mail server. Postal eliminates vendor lock-in and variable costs, though it requires DevOps resources to deploy and monitor reliably.