https://www.theverge.com/2018/7/25/17611358/microsoft-outlook-com-dark-mode-theme-available

Microsoft is introducing a dark mode to the company’s Outlook.com web mail service today. The software maker previously teased the dark mode earlier this month, and previously introduced a temporary version for Halloween last year. This new permanent dark mode can be enabled from the quick settings toggle, and only current works with the default blue theme. It’s a lot more refined than the Halloween mode, with more of a grey appearance than black.

The dark mode for Outlook.com is one of the most highly requested features for Microsoft’s web mail service, and the company says it tuned the Halloween prototype to redesign the colors and code “multiple times” before releasing it today. Outlook.com is now used by more than 400 million active users, and Microsoft recently launched a new design and features for the calendar and contacts sections.