Outbreak Protection

Fortimail 200E running v5.3,build 623,161019

I would like to enable outbreak protection. When enabled I have noticed that a lot of good email gets sent to the outbreak protection queue and sits there for 30 minutes. That is a very long time to wait for an email that came from a legit source. I know that this setting can be lowered down to 15 minutes which I have done. I also know that there is a high and low setting and I verified that my system was set to low.

What criteria does the FortiMail use to determine if an email should be added to this wait queue?

I have attached an image that illustrates the need for outbreak protection.