Hello, collective intelligence.
It is necessary, ideally, an open/OpenSource analogue of Exchange, but this does not exist in nature.
As a living wage - you need a server opensource calendar synchronizer for a whole fleet of Outlook 200333, 2007, 2010 - there are all sorts of things.Just do not touch the mail.You can still contact.
If this is not in nature - what would you advise from a reliable in the sense of groupware for the web? Because my eyes run away from several systems and tons of functionalities offered by them, but first, calendar synchronization is mainly needed(access levels, editing, groups, etc.) and second, contacts and notes, no more.