Microsoft is retiring Themes by Copilot, the AI-generated visual themes in the new Outlook, starting in mid-October 2026. Copilot licence holders will lose the generated themes by late October; a theme already applied stays in place until the user changes it.

The retirement is part of a wider simplification of Copilot inside Outlook. Microsoft has told admins the Outlook Copilot experience will move in October to a simpler, chat-centred design with improved navigation and Work IQ controls, after the feature had spread across a floating button, the ribbon, compose, search and a full chat pane.

Copilot itself is not leaving Outlook: it remains in the ribbon and can be turned off, and drafting and rewriting help in compose stays. The change is Microsoft pulling back a decorative feature and consolidating the surfaces where Copilot can be triggered.