Hello,
I use avast v11.1.2245 on win8x64 pro and have this issue:
1. Open: Mail Shield -> Customize -> Behaviour
2. Uncheck "Insert note into clean message (outgoing)"
3. Click Ok to close Mail Shield Settings
4. Click Ok to close Settings
5. Open Mail Shield -> Behavior again
Expected: checkbox "Insert note into clean message (outgoing)" is unset
Actual result: checkbox is set
Is it bug or feature?