Messaging and groupware is at the heart of business, and applications most people use everyday. While the big names like Microsoft Exchange, Lotus Notes and Google Apps are increasing their influence, enterprises have a number of viable options for open source alternatives.

Of course, there plenty of complaints about the quirks and complications of the big name groupware suites so perhaps it's time to give the lesser-known options a try.

In this installment of 5 open source things to watch, we take a look at open source groupware suites which can communicate without costing the farm.

Bongo

The Bongo Project originally started as a fork of the defunct Hulu groupware suite, which itself was derived from Novell's NetMail.

Bongo includes a server-side email and calendaring app, and a web interface for email and calendar. The developers do not claim Bongo is a replacement for a full enterprise groupware suite, but say it is ideal for SMEs and third party app developers.

Developed in C and Python, Bongo has been active for nearly four years but has not yet released a production version.

Incidentally, the Bongo project leader announced this month that the project needs to be renamed for the 1.0 release. So don't be surprised if Bongo is no longer 'Bongo' when you read this.

Licence: GPL

Citadel

Citadel is a full-featured groupware suite that integrates several applications. In addition to email and calendar applications, there is a mailing list server, search engine, wiki and bulletin board system.

Other features include instant messaging (Jabber), server-side mail filtering and server replication so users across multiple domains can be spread out across any number of Citadel servers for "infinite horizontal scalability".

With support for IMAP and GroupDav, Citadel integrates with the popular third party front ends and anti-spam software.

Version 7.84 was released in August this year.

Licence: GPL