TrueNAS Core - TrueNAS Core (formerly FreeNAS) is a storage operating system strong and robust enough to meet the needs of enterprise level businesses.
Zimbra - Zimbra is trusted by over 500 million users to increase productivity with a complete set of collaboration tools while maintaining total control over security and privacy.
OpenMediaVault - OpenMediaVault is the next generation network attached storage (NAS) solution based on Debian Linux.
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
Unraid - Simplicity. Flexibility. Scalability. Modularity. Unraid empowers you to build the system you’ve always wanted using your preferred hardware, software, and operating systems.
mailcow - An open source mailserver suite.