hello,
you can add policies from "mail policies " tab and add the policies you want.
and for the attachments you can add an incoming content filter with the below details:
from "mail policies" tab > incoming content filter" > add filter.
condition: attachment file info > file name > from the drop down list select ends with and add the regular expression " \.msc " by this it'll detect attachment that ends with the specified extension.
Action > Drop , or any other action you want.
hope this will help,
Ruba