SOGo could be an interesting open-source option as a groupware. https://sogo.nu/ https://sogo.nu/ They offer a demo here http://demo.sogo.nu/SOGo/ http://demo

SOGo could be an interesting open-source option as a groupware. https://sogo.nu/ https://sogo.nu/ They offer a demo here http://demo.sogo.nu/SOGo/ http://demo.sogo.nu/SOGo/ The account sogo1, sogo2, sogo3 are available to login and see what it looks like.