Similarly, when you compose an email the message body is also in white.
The screenshot below is an example of how the black theme changes certain aspects such as the folder view and toolbars to black but leaves the email preview pane in white. Some aspects of the black theme were still fully illuminated, such as when you read or composed a message. However, unlike Outlook Web App, or, Microsoft Teams, the black theme was not a true dark mode. The black theme has been around in Outlook for Windows for some time.
