The alternative look makes Outlook.com look a little moodier.
Outlook.com's dark mode is available now.
Dark mode is live for Microsoft's Outlook.com, nearly a year after it was requested.
The alternate color setting presents the webmail service's default setting with a dimmer look suited to reading in low-light areas.
It can be activated by going to the Quick Settings at the top right of the Outlook interface and clicking the slider below the themes. Microsoft notes that it "only supports the default blue theme right now."
The company also highlights that dark mode's reading pane also retains the dim background "to minimize the amount of eye strain that people felt," but you can change that by clicking "Turn on the lights." You can find it to the left of "Reply" in individual emails.
If you're looking to maximize your Outlook experience, check out our guide to its best new features.