I'm sorry to say that I'm another Android friend who doesn't know if that will work. It really depends on how MS has written the available widgets for the Outlook app, which is probably what you'll be using for your Exchange account.

Each app is responsible for its own widgets, which get installed/uninstalled with the app. If they haven't created a widget like that, then maybe another email handling app has done so. You'll need to find one that supports Exchange.