from that thread

for those who hates the "Message Sent" notification after sending an SMS, this is the steps to remove the bubble notification...this is the STEP by STEP method to do it in case some of you guys dont get it right...
1. First, you will need to download a Registry Editor to help you do it...
a good one will be the freeware PHM Registry Editor
or for those who got the Resco Explorer, you can use the Registry Editor that comes with it...
2. using the Registry Editor, navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Inbox
3. Next, click on Inbox (make sure the Inbox is highlighted) and select Edit, New Key
4. Name the New Key as "Settings"
5. Click on "Settings" (make sure the Settings is highlighted) and select Edit, New String Value
6. On "Value name:", key in SMSNoSentMsg and in "Value data", key in 1
7. Soft reset your device and test it with one SMS, and you will notice that the SMS Sent bubble is being disabled