Segregate non-Duo email accounts for deep scanning?

For Wiscmail tech team.

All email is scanned for viruses but other than that, anything coming from @wisc.edu addresses is assumed to be trusted. Emeritus/ex-employees/ex-students who are not Duo-eligible might account for a lot of the spam/phishing we see. Would be nice to segregate non-Duo user mail and deep scan that.