Encrypted Documents are blocked - but need to allow SMIME.

Hey all, 

I have a replacement message and a quarantine procedure for Encrypted documents using the canned filter on the Fortimail. I've tried placing application/smime and even a custom File Format of smime.p7s higher up in the order, but the FM still quarantines every digitally signed email. 

Luckily, very few of our external contacts send SMIME messages - but those that do have a manual release process for every one. 

Can anyone think of a way of setting a higher action priority on a Fortimail content filter type?

Thanks