Communication & Email OSS tools — 5 tracked with release & CVE alerts

Radicale Healthy open source

A simple CalDAV (calendar) and CardDAV (contact) server.

Modoboa Mixed open source

Mail hosting and management platform including a modern and simplified web user interface.

synapse Healthy open source

Synapse: Matrix homeserver written in Python/Twisted + Rust

Baikal At Risk open source

Baïkal is a Calendar+Contacts server

zulip Healthy open source

Zulip server and web application. Open-source team chat that helps teams stay productive and focused.

Tools