User impact: Users may see unwanted add-ins appearing automatically across all Outlook clients.

More info: These add-ins are configured to be available to users by admins but aren’t expected to be automatically installed. To bypass this issue, admins can run the “Set-App -Identity -OrganizationApp -PrivateCatalog -DefaultStateForUser Disabled” command to remove add-ins that are unintentionally appearing.

Current status: We’re deploying our permanent fix to the affected environments, and we currently estimate the deployment will complete by Monday, September 21, 2026. We’ll continue to monitor the deployment to ensure that our remediation timeline is accurate.

Scope of impact: Impact may occur for some users that may see unwanted add-ins appearing automatically across all Outlook clients. This section may be updated as the investigation progresses.

Start time: Friday, July 17, 2026, at 10:26 AM UTC

Root cause: A portion of the Exchange Online add-in sync pipeline isn’t processing add-in state information as expected. This is causing incorrect EnabledStatus values being returned and Outlook automatically displaying add-ins configured as Available, which is resulting in impact.

Next update by: Wednesday, September 16, 2026, at 6:30 PM UTC