Is there a way to have Norton AntiSpam re-scan items from a PST?

I'm trying to re-scan items that I'd downloaded before installing Norton Security (22.9.1.12) for SPAM/malware/etc.  Although I am able to mark an item as SPAM, or mark it as clean, I don't seem to see a way to re-scan an email folder or PST file as a whole for these threats.  Is there a means to do so?  (Outlook 2013 with Norton AntiSpam add-on)

I'm not very worried that I have something already - more so, I'd just like to be able to re-scan some older items to be certain, and to find anything that might have been "clean" at the time, but since found to be a problem.

 

Thank you;