Citadel [1] is an easy and versatile groupware alternative with tight integration and plenty of powerful features. While your fellow admins are still wrestling with Kolab2 and Horde, you might find that your Citadel installation is already configured and running securely. Citadel delivers an Exchange-killer groupware server, a web and telnettable BBS, and an online PIM suite using the standard GroupDAV protocol. You won’t need your Linux administrator’s handbook, and you won’t need a lot of time. Citadel’s 45 minute Easy Install involves only a handful of key presses and some very rudimentary knowledge of your system. I initially stumbled across Citadel after giving up on getting Kolab2 to work. It was a happy accident, because I’ve found Citadel more powerful than Kolab2 and remarkably easy to configure.