If you want to lockdown a user of a Windows Mobile device to not send/receive SMS messages or eMails, you can use a blacklist. First enable Disallow policy on the device and then list all apps you dont like the user to run.
REGEDIT4
;Enable blacklist of applications that should not run
[HKEY_LOCAL_MACHINE\Security\Policies\Shell]
"DisallowRun"=dword:1
;Add entries to blacklist of applications that should not run
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer\DisallowRun]
"1"="tmail.exe"
"2"="sms.dll"
"3"="poutlook.exe"
;add more here as "3", "4", "5", etc.
tmail.exe, sms.dll and poutlook.exe are responsible for message handling on the device. If you disallow them, the user cannot start them anymore.
