We have successfully tested with Exchange Server 2003 and 2007. There are 4 boxes (and one checkbox) of info that need to be filled out.
When you click on the Import from Exchange the info you will need to enter info as follows:
The first box ( top left) is Exchange server. This should be the name of the server how you would access it for Outlook webmail (ex . webmail.mydomain.com or ip address)
The second box ( top right) should be the Windows Active Directory domain name. This may not be the same as your email@example.com domain
If you use SSL please check the box ( this is recommended)
The third box (bottom left) is your Active Directory user name (ex. firstname.lastname without the "@domain.com" part)
The fourth box (bottom right) is your Windows Active Directory password.
If you want to import your own calendar leave the last box empty.