Unfortunately, Microsoft excluded support for Exchange 2003 in its major upgrade of Office 2011 for Mac. Official reason is that Exchange 2003 is too old, which is of course a weak justification considering that even the latest iOS 4.2 for iPhone/iPod and iPad do support Exchange 2003. But then again, also Apple excluded direct Exchange 2003 support in Mail and iCal on OS/X 10.6 Snow Leopard. There is a way around this though, using a freely downloadable and open source software called DavMail. Just Google “DavMail Mac binary download” to find the nearest/latest available download location.