Cached Exchange Mode is controlled by the following key;
[HKCU\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\<ProfileName>\13dbb0c8aa05101a9bb000aa002fc45a]
00036601 (REG_BINARY)
enabled value; 84 01 00 00
enabled with Public Folders/Favorites: 84 05 00 00
disabled value; 04 00 00 00