[haus]

From your other post (linked to the TP thread), when this registry entry is set:

HKLM\Software\Microsoft\Inbox\Settings
SMSNOSentMsg = 1

This disables the Windows Mobile notification of SMS sent. I'm 99% sure my Intrepid had this set as the default. It stuck in my mind because on the TP it was set to 0, which allows the notification to show after every outgoing SMS.

Separately, people are getting a beep when the Samsung SMS program shows "Sending 1/1...", I think?

I'm offline for a couple of days, will look into it more after the weekend. It's solvable, since mine doesn't do it, I just don't know what the key is yet.

This is kind of off the wall, but what if you turn your ring volume all the way down? My ringer is on vibrate even when the phone "sound" is on, so my ring volume defaults to "0" (lowest point on the little bar).