Is there a way to process folder through spam filter?

I've just migrated all of my father's emails to my zimbra server from outlook. Everything migrated fine, but he seems to thing that using a deleted folder is the best way to archive things. There were 40,000 emails in his deleted items folder!!! Most of those emails are crap/spam/junk.

There were over 7400 emails that were "mail undelivered" messages because his outlook was getting exploited. Anyway... Now that I have transferred them all to the Zimbra account, I have created an "Archived" folder and moved all the emails from his deleted folder to his new Archived folder. I went through and deleted those undelivered emails as mentioned but I would now like to utilize Zimbra anti-spam functionality and scan his Archived folder for any spam messages and move them to the junk folder.

Is there a way that I can do this either through the user panel, admin panel or command line?

Nobody knows how to do this? There has got to be a way to scan a folder for spam after importing emails?