Stuck letters in the queue - fortiguard outbreak protection

This post is not very clear but I am going to answer what I think you are asking.

The purpose of the Outbreak Protection is to queue suspicious emails for a period of time (default 30mins) and rescan using FortiGuard to allow time for the FortiGuard Analytics to detect emerging threats.  Delay to emails using this method is expected but they should be released once they reach the queue timeout period.  The queue period can be lowered, however it will reduce the detection efficiency.