Why can't I release more than five messages in Proofpoint?

If you try to release and or safelist more than five messages, you will receive the following error: 

spam.huit.harvard.edu says: 

Release and Allow Sender : Cannot be performed on more than 5 message/messages.

This is a setting maintained by Proofpoint in order to insure that you do not release spam or phishing messages into your in box. This setting cannot be changed.