Power Suite Ubuntu x86/OS Enhancement Utility/Notification
From ESS-WIKI
You can toggle the system notification feature of Ubuntu ON/OFF by clicking the "Stop System Notifications" button.
Usage steps:
Step1. Select the “OS Enhancement Utility” page.
Step2. Click on "Stop System Notification" switch button.
Step3. Click on "Confirm" to change the settings.
Step4. Checking the message notification bar at the top of the Ubuntu desktop, you will find that "Do Not Disturb" has been turned on.