The Barracuda spam filter uses a scoring system when deciding to block, quarantine, or deliver an email. Part of this scoring system is based on a user flagging quarantined emails as spam or not spam. This results in fewer spam emails reaching your quarantine inbox over time.
From time to time, Apparatus will fine tune the global settings within the Barracuda in order to protect against certain spam threats. This may result in a large reduction in the percentage of the spam items that end up in your quarantine inbox.