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.
OpenGroupware.org is a set of applications for contact, appointment, project, and content management. It is comparable to Exchange and SharePoint. It is accessible using Web interfaces or using local clients via WebDAV, GroupDAV, and CalDAV. Custom applications can be developed using the XML-RPC API. OpenGroupware.org runs on almost every GNU/Linux system.
NullLogic Groupware is a modular Web-based groupware and email system designed for contact management and event scheduling. Additional features include private messaging, public discussion forums, webmail, shared bookmarks, file sharing, call tracking, order processing, an XML-RPC API, and integrated POP3 and SMTP servers.
Hep Message Server is software that transfers messages between different messaging systems. Eventually, it should transparently route messages between email, weblogs, and instant messaging. Currently Hep does one thing: fetches news feeds from Web sites and lets you view them in your email client.
Kerio MailServer is a secure corporate Internet messaging server for SME. It integrates SpamAssassin, McAfee anti-virus, SSL encrypted POP3, IMAP4, SMTP, WebMail (HTTP) and WAP protocols, attachment/content filtering and a MAPS/user-defined anti-spam database. It supports multiple domains, automated replies, SMS notifications, shared and public folders, email folder backup, full Active Directory implementation, mailing lists, and shared contacts. It runs on Red Hat 7 and 8, Windows 98/ME/NT/2000/XP, and Mac OS X 10.2, and is available with English, French, Dutch, and German user interfaces.
phlyMail is a groupware, webmailer, and PIM. It offers unlimited nested groups, unlimited POP3/IMAP profiles, quotas, an integrated address book, a calendar with multiple reminders and event repetitions, a file manager with an integrated WebDAV server, the ability to send faxes, SMS support (which lets you send SMS, get reminded of events via SMS, and get email notification via SMS), a bookmark manager, themes, and multilingual support. It uses either sendmail or SMTP to send email, and can handle MIME and SSL connections. Support for IDN (Internationalized Domain Names) is included. Through its modular design, it's easy to add completely new features as modules, which can be plugged into the system.
Kerio MailServer is an email and collaboration suite that comes integrated with direct over-the-air (OTA) ActiveSync support, over 14 anti-spam layers (including SpamAssassin), dual anti-virus options (including a ClamAV plugin), collaboration features in Outlook, Entourage, Outlook Mobile, VersaMail, WebMail, and iCal, email archiving, and live automated backups. It supports a variety of SSL-encrypted communication protocols including POP3, IMAP, STMP, and HTTP for WebDAV, CalDAV, Web mail, and wireless ActiveSync. Wireless capabilities include direct email push, synchronization of calendar events, contacts, and tasks, and remote wipe for Windows Mobile devices to delete company data in the event the device is lost or stolen. Authentication options include Active Directory, Apple Open Directory, PAM, and an internal database. It can be administered remotely using an encrypted channel.