Kolab is an open source groupware program suite. It consists of the Kolab server and a wide variety of Kolab clients, including Horde Webmail (currently is alpha/beta development), KDE Software Kontact (fully working in KDE 3.4.1), Mozilla Thunderbird with the SyncKolab extension (alpha/beta), and Microsoft Outlook with the Toltec Connector (stable release) or the Konsec Konnektor (stable release).