Open Source Alternatives to Microsoft Exchange Server

An email and calendar platform that provides messaging and scheduling capabilities for organizations. The software manages professional communications and coordinates calendars across a user base to facilitate organizational productivity. It is used by IT professionals to deploy communication infrastructure and by educators and students to handle academic correspondence. The product is deployed as part of a broader suite of productivity tools and is available through various academic plans tailored to the needs of schools and educational institutions. It integrates with other productivity applications to ensure that users can access their mail and schedules across different devices. The system is designed to be managed by IT administrators who oversee the security and distribution of email services within a school or business environment.

Whether you want to cut software costs or escape vendor lock-in, these open source alternatives to Microsoft Exchange Server give you an option you fully own. You can self-host them, so your data stays on infrastructure you control. This page lists 7 open source alternatives to Microsoft Exchange Server. The most popular are Stalwart Mail Server, Maddy Mail Server and Mox. Most use the GPL-3.0 or MIT license, and 7 offer an official Docker image.