DavMail, Thunderbird, IMAP, POP3, OWA etc. Don't spend too much time on ActiveSync. Be aware that ActiveSync requires a direct link to MsExchange Server (inside a corporate network).
There are multiple tools to access Outlook and Microsoft Exchange database.
From the Microsoft website is the following statement:
Microsoft ActiveSync 4.5 is the latest sync software release for Windows Mobile-powered devices. ActiveSync provides a great synchronization experience with Windows®-powered PCs and Microsoft Outlook right out of the box. Note: Microsoft ActiveSync works only with Windows XP SP2 or earlier.