One of my clients like to have a system with a shared calendar/e-mail and filesharing. Something like phpgroupware or Zimbra. I have had a look at the Zimbra documentation and i think it is not compatible with my ISPCOnfig server. I also do not know if phpgroupware is compatible. Is there anyone out here, who knows such a system, which is easy to use and compatible with ISPConfig? (Document sharing is the most important feature). Any advise is very welcome!