As we have assumed an Ubuntu Server in our previous articles, we will continue this way. Citadel is available for Debian (Lenny) and Ubuntu 8.04, so you do not need to do anything except issue the command apt-get install citadel-suite as root from the command line.
Although this will install Citadel on your system, go for an apt-get install citadel-mta to install Citadel Mail Transfer Agent. If everything is compiled, in place and running, you will receive an “already installed" message.
Be sure to follow the installation carefully and record your answers that you give to the installer’s questions, such as ports, username, password etc.. We will use them for configuration.
Before we go on, I must tell you that Citadel works with the concept of “rooms." Rooms can be e-mail, calendar, contacts, tasks, chat room, anything.