Citadel is an integrated email and groupware server built around a room-based architecture. A single installation can provide conventional Internet email alongside calendars, contacts and several forms of online collaboration.
The server includes its own SMTP, IMAP and POP3 services rather than requiring separate mail-server components. Users can work through conventional mail clients or through the WebCit browser interface.
Citadel’s room model is used for mail folders, discussion areas and other shared content, providing a consistent approach to private and collaborative information.
This is free and open source software.
Key Features
- Built-in SMTP and ESMTP mail transport.
- IMAP and POP3 access for conventional email clients.
- WebCit browser-based interface.
- Calendars and address books.
- Forums and discussion areas.
- Mailing lists with individual-message and digest delivery.
- Multiple and virtual email domains.
- Users can have multiple email addresses across different domains.
- Instant messaging facilities.
- Wiki and blogging functionality.
- RSS aggregation.
- Room-based organisation of private and shared content.
- DKIM signing for outgoing email.
- Designed as a self-contained server without requiring a separate IMAP or SMTP package.
Website: www.citadel.org
Support:
Developer: Citadel.org
License: GNU General Public License v3.0
Citadel is written in C. Learn C with our recommended free books and free tutorials.
Related Software
| Groupware Software | |
|---|---|
| Zimbra | Full-featured collaboration suite |
| SOGo | Collaborative software server focusing on simplicity and scalability |
| Kolab | Secure, scalable, and reliable groupware server |
| eGroupware | Enterprise ready web-based groupware suite |
| OpenMeetings | Video conferencing, instant messaging, whiteboard, and other groupware |
| Citadel | Complete and feature-rich groupware server |
| Kopano | Groupware application suite originally based on Zarafa |
| grommunio | Modern, digital communication and collaboration |
| GroupOffice | Groupware and CRM platform for enterprises and the public sector |
| HordeGroupware | Popular full-featured groupware server |
Read our verdict in the software roundup.
| Email Servers | |
|---|---|
| Exim | Highly configurable mail transfer agent |
| OpenSMTPD | Implementation of the server-side SMTP protocol with additional extensions |
| mox | Modern, secure, all-in-one email server |
| DBMail | Enables storing and retrieving mail messages from a database |
| WildDuck | Opinionated email server |
| Stalwart | All-in-one mail and collaboration server |
| Mailu | Self-hosted mail server stack |
| Mail-in-a-Box | Self-hosted email server solution |
| Postfix | Popular mail transfer agent |
| Maddy | Composable all-in-one mail server |
| Haraka | Modern SMTP server |
| Dovecot | Secure POP3 server that supports mbox and maildir mailboxes |
| Courier | Integrated mail/groupware server |
| Cyrus IMAP | Email, contacts and calendar server |
| Zimbra | Zimbra Collaboration Suite |
| Modoboa | Mail hosting and management platform |
| Citadel | Exchange-killer groupware server |
| chasquid | SMTP server with a focus on simplicity, security, and ease of operation |
| Sendmail | Mail transfer agent for sophisticated mail configurations |
| dma | DragonFly Mail Agent |
| DavMail | POP/IMAP/SMTP/Caldav/Carddav/LDAP exchange gateway |
Read our verdict in the software roundup.
 LinuxLinks helps you discover the best free and open source software for Linux. Explore our extensive collection of recommended applications, including alternatives to popular proprietary software.We also publish software reviews, Linux tutorials, hardware reviews, free programming books and articles covering the wider open source community. Browse our Linux resources to discover more. Know a useful free and open source Linux application we haven't covered? Suggest a program for inclusion. Has your software been featured on LinuxLinks? Display one of our Featured on LinuxLinks badges on your website or GitHub README. |
Please read our Comment Policy before commenting.