Microsoft is retiring Themes by Copilot in Outlook worldwide, with the removal starting in mid-October 2026 and expected to finish by late October 2026, according to the Microsoft 365 Message Center post MC1492954, published on October 9.

The change applies to users with a Copilot license on new Outlook for Windows, Outlook for Android, Outlook for iOS, Outlook for Mac, and Outlook on the web.

Once the retirement reaches an account, Themes by Copilot is removed from Outlook's settings. Copilot themes can no longer be selected, and anyone who switches to a different theme cannot go back to a Copilot one afterward.

Microsoft gives no reason for the retirement in the message. Outlook users without a Copilot license are not affected by the change.

A Copilot theme that is already applied stays in place until the user changes it. Themes set to refresh automatically also remain applied, but they stop refreshing and keep the imagery they show at the moment of the retirement.

Themes by Copilot was offered to Copilot Pro and Microsoft 365 Copilot subscribers in the Appearance settings of Outlook. Users could start from a weather type or a location, either their own or one of more than 100 curated destinations, and then choose a realistic, oil painting, or cartoon art style.

Each generated theme combined a wallpaper, shown as the background on desktop or at the top of the mobile apps, with a matching accent color for the rest of the interface. Refresh intervals ranged from every few hours to daily, weekly, or monthly.

Microsoft launched a separate collection of standard themes, which are not AI-generated, for all Outlook users regardless of license status, with color options such as green, red, and purple. The retirement notice covers only Themes by Copilot.

The Message Center post states that no action is required. Users who like their current Copilot wallpaper should still keep the following in mind before the removal arrives:

1. Leave the current Copilot theme applied if the imagery should stay, since switching to any other theme removes the option to return.
2. Expect auto-refreshing Copilot themes to freeze on their current image once the retirement reaches the account.
3. Pick a replacement from the standard theme collection in Outlook's Appearance settings if a frozen image is not wanted.

The removal comes shortly after Microsoft announced plans to block .msix attachments in new Outlook in November.

Microsoft is rolling the retirement out gradually across the mid to late October window, so Themes by Copilot remains visible in Settings on some accounts until the removal reaches them.