Citadel is an advanced messaging and collaboration system for groupware and BBS applications. Users can connect to Citadel using any telnet, WWW, or client software. Among the features supported are public and private message bases (rooms), electronic mail, real-time chat, paging, shared calendaring, address books, mailing lists, and more. Unlike other collaboration servers, Citadel provides its own data stores and is therefore extremely easy to install; you don't have to "bring your own" email and database because they're built in. The server is multithreaded and scalable. In addition, SMTP, IMAP, and POP3 servers are built-in for easy connection to Internet mail. Citadel is both robust and mature; it has been in production since 1987.
| Tags | Communications BBS Chat Email Mail Transport Agents Mailing List Servers Post-Office IMAP POP3 Office/Business Scheduling groupware |
|---|---|
| Licenses | GPL |
| Operating Systems | POSIX |
| Implementation | C |
Recent releases


Release Notes: New features include a greatly improved XMPP (Jabber) service for better compatibility with more instant messenger clients, a completely new bulletin board (forum) view that is greatly improved in both performance and features, a brand new multiuser chat facility redesigned for better access through a Web browser, and many bugfixes and performance enhancements.


Release Notes: The following issues have been fixed: line-buffered I/O was handled incorrectly; when configuring a brand new Citadel installation for LDAP authentication, the LDAP configuration would be erased on the first server run and would need to be re-entered; issues with LDAP authentication on 64-bit systems; deleting the last unread message in a room would sometimes fail to mark the room as not containing new messages; a memory leak was associated with binary downloads; a small bug was in the Wiki room mode on 64-bit systems; a buffer size issue was in the text mode client.


Release Notes: Recurring events are now supported across the entire calendar system, as well as all-day events which span multiple days. The WebCit framework is now templatized. The mailbox summary view is now faster and more versatile. Support for virus scanning with ClamAV was integrated. Inline images are supported in message views. Interoperability with vCards generated by third-party address book software was improved. Fonts in WebCit are now relative sized, making the whole site look better on screens of all sizes. Performance improvements, user interface enhancements, and bugfixes were made.


Release Notes: When running mailing lists, the List-ID field is parsed and generated. Improved handling of the refcount_adjustments.dat file to prevent a rare condition where the file can't be renamed and therefore cannot be processed. The display of incoming instant messages through an IMAP client has been removed, because XMPP is now supported, so it would be redundant for most users.


Release Notes: This version adds an XMPP (Jabber) service. It also adds more security and granularity to the options provided by Citadel-hosted mailing lists.
Recent comments
28 Dec 2006 08:07
Move over postfix....
When hosting my personal and church site, I needed a flexible, easily administered solution. After implementing (yes, successfully) a postfix virtual email system, I recently found Citadel (actually, I had crashed my server, and was seriously dreading re-implementing postfix).
Installation? EasyInstall, and boy is it
Configuration? Browser based. Here's what it took:
1) Receiving emails for domaina.com, domainb.com, ...
2) Enter the users for each domain
3) Tell it I had spamassin running on the machine.
I was floored. It was receiving all my emails. Amazing.
Then, I needed a mailing-list type functionality. Create a "room" called Finances. Subscribe to that room for the people who need updates, and suddenly all emails to room_finances@domain.com are now distributed as a mailing list. Wow.
An excellent product, excellent development community, very good web client/email tool. What more could you ask for?
Give it a shot today...
13 Sep 2005 09:26
Looking for an "Exchange Killer?" Try Citadel.
Years ago, users expected their electronic mail systems to send and receive
messages, and not much else. Today’s users, however, are more
sophisticated. They expect Personal Information Manager (PIM) functions
such as calendars and address books, a choice of access methods, and a
variety of groupware functions. Yet the goal of providing an easily
deployable open source groupware platform has, until recently, been somewhat
elusive. Most of the popular choices have been built as traditional web
applications, requiring a system administrator to install and configure a
mail server, a web server, and a database server before being able to
begin the groupware installation. Moreover, the resulting functionality has
followed a cookie-cutter style modeled after proprietary systems that some
consider outdated. This is why you might be surprised to learn about the
existence of a project that not only solves the complexity problem, but takes a fresh new approach to groupware.
Citadel is an open source groupware server that has
its roots in online communities. You may remember the Citadel BBS’s of the 1980's and 1990's; today’s groupware platform carriessame
lineage. But to write off Citadel as an overgrown BBS package would be an
unfair underestimation of the powerful abilities of this impressive
platform. While most groupware systems center around the automation of
business processes, Citadel offers a platform that you can build a community
around. It centers around the idea of connecting people together in real
time using a set of tools that focuses on people, not processes.
System administrators will find Citadel refreshingly easy to install.
There is no need to "bring your own" mail server, web server, or database
server. Citadel has all of its data stores and protocols built in. It
uses the powerful Berkeley DB [www.sleepycat.com] database for all
of its storage needs. All of the popular electronic mail protocols are
built in, including ESMTP, POP3, and IMAP, as well as GroupDAV for
connecting popular open source PIM clients such as Kontact and Evolution.
There is no need for the tedious mucking about with cryptic Sendmail
configuration files or obscure Cyrus commands; everything is configurable
through an easy to use browser-based interface.
For those who are nervous about the prospect of compiling software from
source, Citadel provides an "Easy Install" script that handles this task
for you. Entering one command at a shell prompt downloads an install
script from the Citadel project's download server, and performs the entire
installation automatically.
14 Feb 1999 22:12
Cynbe ru Taren's original comments on Citadel
Citadel is a room-structured message system. The fundamental
design goal is to provide a congenial forum conducive to interesting
discussions. The software is intended to be as unobtrusive, unintrusive
and unconstraining as possible. In software as elsewhere, good engineering
is whatever gets the job done without calling attention to itself.
The fundamental design metaphor is that of a building consisting of
a series of independent rooms, each of which hosts a discussion devoted
to a particular topic. Messages are stored and retrieved in chronological
order within each room. Messages are formatted to the caller's screen width.
Callers may travel freely between the rooms,
reading old messages and posting new ones. New rooms may be created
at will, and old ones are deleted when they empty of messages.
People familiar with other electronic message systems may wish
to compare Citadel rooms with EIES conferences, ArpaNet mailing
lists, individual "linear" BB systems or whatever; the parallels
are not exact but the functions are similar.
The fundamental Goto, Read and Enter commands have been streamlined
as much as possible. The message display format has a minimum of
unnecessary noise: the topic is implicit in the message's location
within a room, no explicit TO field is present, no message ID # is
printed, no redundant "END OF MESSAGE" blurbs etc. The most common Goto,
Read and Enter commands are all single-key. Citadel automatically
skips rooms which have no new messages, and old messages in the
current room. (Less concise commands are of course available to
override this.)