Adding Attachments freezes Outlook 2007 - SEP suspected

We're having an issue with Outlook 2007 and attachments, and right now Symantec Endpoint Protection 12.1.3 is on the suspect list.

We recently moved to a new file server, which is Linux-based; before we were on a Windows-based file server. The Windows server had SEP installed on it. I believe there was a setting in SEP which caused it not to scan files coming from sources that also had SEP installed. However, since this new server doesn't have SEP, we believe that the Outlook add-in is scanning every file being attached to e-mail.

Is there a way to exclude the new file server from being scanned, or to tag it as a trusted source? We can't install SEP onto it, for technical reasons, but it does have its own AV product on it.