Select the Sun icon to change to a white background.This is possible by clicking on Sun/Moon icons located at the top of the message window, as shown below: It is quite convenient to toggle between Dark Mode ON or OFF while reading messages. How to Toggle Between Dark Mode ON and Dark Mode OFF?.Note: The new theme will be applied to all of the MS Office apps. Next, from Office Themes, choose Black.From the toolbar, select the File > Office Account.The steps to switch to the Black theme/Dark mode are described below: Other than that, we have options like Black and Dark Grey, and the Black theme is also referred as Dark mode. Enable Dark Mode in MS Outlookīy default, the Office theme is set to Colorful, but one can also select a White theme. The Dark mode option is not limited to the desktop client as it is also available for Outlook Web app and. FYI, this only works on Office 365, Office 2016, and Office 2013. Microsoft recently released Dark mode option for the Microsoft Office suite, along with dark grey and colorful themes. After all this time, Outlook still manages to surprise us with its splendid features and new add-ons.