Once installed, you can access Citadels through multiple interfaces:

Because Citadels is open-source software under the GNU General Public License (GPL), it is .

Citadels supports standard protocols (IMAP/SMTP/GroupDAV), meaning you can use it with Outlook, Apple Mail, or Thunderbird.

Keep your contacts synchronized across devices.

This blog post covers , the fast, versatile, and open-source groupware system. Whether you are a system administrator or a curious user, this guide will walk you through what Citadels offers and how to download and get started for free.