Prevent Email All Users page from reloading and resending the emails

Problem: If you have sent out a mass email using WHM's Email All Users function, leave the browser tab open, put your computer to sleep, wake your computer... the browser tabs will reload. Including the Email All Users tab. This results in the mass email being sent out again (every time the tab is refreshed).

Suggestion: Once the email is sent out, move to a separate confirmation page or otherwise prevent the emails being sent out again on browser tab reload.