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.
DokuWiki - DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database.
iRedMail - A fully fledged, free email server solution, an open source project (GPL v2).
Wiki.js - An open source, modern and powerful wiki app built on Node.js, Git, and Markdown.
mailcow - An open source mailserver suite.
TiddlyWiki - a non-linear personal web notebook