Kolab – collaboration software

Kolab is an open source groupware solution. It consists of the Kolab server and a wide variety of Kolab clients, including KDE PIM-Suite Kontact, Horde Webfrontend, Mozilla Thunderbird and Mozilla Lightning with SyncKolab extension and Microsoft Outlook with proprietary Kolab-Connector PlugIns.

Kolab adds intelligent interaction between the components, a web administration interface, management of free-busy lists and more. Major components of the Kolab Server are OpenLDAP, Postfix, Cyrus IMAP, Apache, SASL, and OpenSSL.

It supports mixed client environments (Outlook/KDE) because of an open storage format. Any email client speaking standard protocols can be served.

Kolab2 Server uses the OpenPKG environment to provide a constant base across multiple platforms and distributions.

Features include:

  • Full seamless support of mixed clients environments (Outlook, KDE, Web etc).
  • Support for the K Desktop Environment with Kontact.
  • Support for Microsoft Outlook with proprietary connector PlugIns.
  • A web administration interface.
  • Configuration data is kept in a LDAP directory.
  • A global LDAP adressbook for contacts.
  • IMAP4rev1 as well as POP3 access to mail.
  • Full support for client-side PGP and S/MIME email encryption (officially Sphinx-interoperable).
  • Full support for shared calendars with IMAP ACLs.
  • Full support for shared contacts with IMAP ACLs.
  • Fully offline capable using KDE Kontact or Microsoft Outlook.
  • Support for server side resource management (e.g. rooms, cars).
  • Full support for freebusy handling.
  • Cross-Folder-Search.
  • Birthday Calendar that automatically shows the birthdays of all your contacts from your address book in one neat calendar.
  • Dedicated Out-of-Office settings where you can specify when you are in vacation and which message should be sent under which circumstances.
  • Email tags.
  • Notes.
  • Folder management.

Developer: The Kolab-Project and the Kolab-Konsortium
License: Various freely distributable licenses


Kolab is written in C++ and PHP. Learn C++ with our recommended free books and free tutorials. Learn PHP with our recommended free books and free tutorials.

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