I have been researching the same issue for days now and all I have been able to find out is this. For some reason, you cannot disable Outlook Stationery with any default group policies including the ones in the Office Resource Kits.
It seems that Outlook Stationery can be disabled using a custom group policy.
You will need to create a custom administrative template and add it to your GPO by right clicking the Administrative Templates under User Configuration.
These templates will allow you to prevent the user from choosing a stationery under options, plus it will prevent them from creating new messages using "More Stationery" from the action menu.
Just copy and paste the following into notepad and save in the C:\windows\inf folder with the preceding file names. (Note: Make sure the file extension is ADM and not ADM.TXT)
For Outlook 2003, name the file "Stationery11.adm" and paste the following text.
CLASS USER
CATEGORY !!CustomUserSettings
CATEGORY !!Outlook2003
POLICY !!DisableNewStationery
EXPLAIN !!DisableNewStationery_Explain
KEYNAME "Software\Policies\Microsoft\Office\11.0\Common\MailSettings"
VALUENAME "NewStationery"
VALUEON ""
VALUEOFF NUMERIC 1
END POLICY
POLICY !!DisableNewTheme
EXPLAIN !!DisableNewTheme_Explain
KEYNAME "Software\Policies\Microsoft\Office\11.0\Common\MailSettings"
VALUENAME "NewTheme"
VALUEON ""
VALUEOFF NUMERIC 1
END POLICY
POLICY !!DisableMoreStationery
EXPLAIN !!DisableMoreStationery_Explain
KEYNAME Software\Policies\Microsoft\Office\11.0\Outlook\DisabledCmdBarItemsList
VALUENAME "TCID99"
VALUEON "5611"
VALUEOFF NUMERIC 1
END POLICY
END CATEGORY
END CATEGORY
[strings]
DisableNewStationery="Disable Modify Default Stationery
DisableNewStationery_Explain="Prevents users from changing the default stationery. NOTE: To disable, set to 'Not Configured' or move GPO out of scope.
DisableNewTheme="Disable Modify Default Theme
DisableNewTheme_Explain="Prevents users from changing the default theme. NOTE: To disable, set to 'Not Configured' or move GPO out of scope.
DisableMoreStationery="Disable More Stationery
DisableMoreStationery_Explain="To disable Actions > New Mail Message Using > More Stationery. This prevents creating a new message using stationery.
Outlook2003="Outlook 2003
CustomUserSettings="Custom User Settings
