As Per the QStartGuide.pdf (Search for On End-User Desktops (if running the SSDM))
The Outlook Client is Required, and as of 4.8.1 only the 32-bit edition of Outlook 2013, 2010 or 2007 must be set as the default mail client.
If migrating to Exchange 2013 or Office 365, the required Outlook client must conform to Microsoft's requirements for Exchange 2013 or Office 365, respectively.
