Discover Sogo, the best open source alternative to Microsoft 365 – Scalable groupware with calendars, contacts, and email.
SOGo is a fully supported and trusted groupware server, designed for businesses and communities to seamlessly share calendars, address books, and emails. Released under the GNU GPL/LGPL v2 and above, SOGo focuses on scalability and open standards, providing a rich AJAX-based web interface and supporting multiple native clients through standard protocols like CalDAV, CardDAV, GroupDAV, and Microsoft ActiveSync.
SOGo is the missing component in your infrastructure, offering a uniform and complete interface for users to access their information. Its deployment in environments with thousands of users attests to its reliability and scalability.