Does Outlook 2016 have a Quick Look plug-in?
From what I have seen online and from my own uses Microsoft has not written a quicklook plugin for Outlook 2016.

It is odd though that you get some garbled text in the spotlight/quicklook window. On my Mac quicklook only shows an outlook document icon, the (presumably) UUID of the message and date created/modified/last opened info on the mail message.

So your garbled text might indeed be something going wrong with Outlook or even Quicklook trying to read a file it should not.