Trump just has to say this is part of the corrupt government that he will clean up. If you vote Clinton into office you vote for further corruption, this is the chance for the American people to make up their minds: corruption as usual? or make America great again!
Just keep hammering that with the fact that Clinton should have known and the fact that she claims she didn't makes her unfit to run this country.
hammer the fact that Hillary Clinton would not qualify for a security clearance or even be hired by any federal agency with this kind of fact pattern in her background