as far as i know feature has only been introduced in ENS10.5.1. the releasenotes of this version give some more information (McAfee Corporate KB - Endpoint Security 10.5.1 Release Notes PD26909 ), but unfortunately no full-blown product guide is available for this version.
We've found that it blocks any type of script file. ps1, js, etc. And exclusions do not apply to the email scanning feature.