With the new feature of being able to see your quarantined emails, you may want to silence the notifications in case a lot of the emails you get are spam:

To do so login to Barracuda Email Defense with the following URL: https://us.ess.barracudanetworks.com/webui/message-log

Once logged in you will see a settings gear click it and you'll see the options as shown below: 



Once you click notifications settings you will see this screen: 



On this screen you can change the intervals that you receive notifications or you can hit the never option and disable notifications entirely.