http://www.opengroupware.org/screens/index.htmlhttp://www.bongo-project.org/Main_Pagehttp://buni.org/mediawiki/index.php/Meldware_Commu nications_Suitehttp://www.kolab.org/about-kolab-server.htmlhttp://www.scalix.com/enterprise/technology/news_1 1.4.phphttp://www.zarafa.com/?q=en/content/versions