Recovery Manager for Exchange may display an error message reading that Microsoft Outlook is not set as the default e-mail client, whereas it actually is. (4325403)

This could be due to an incorrect version of Outlook Installed. 

WORKAROUND 1:

Uninstall the current Outlook installation and install a supported version (make sure it is a 32 bits version)

DISCLAIMER: Quest does not provide support for problems that arise from improper modification of the registry. The Windows registry contains information critical to your computer and applications. Make sure you back up the registry before modifying it. For more information on the Windows Registry Editor and how to back up and restore it, refer to Microsoft Article ID 256986 “Description of the Microsoft Windows registry” at Microsoft Support.