User impact: Users may have been unable to leverage one or more secondary functions within Outlook on the web.

More info: Users encountering this issue may have experienced impact to one or more of the following features within Outlook on the web:

– Search results and suggestions for Email, Calendar and Contacts
– Content Labeling Policy functionality
– SafeLinks settings
– Outlook add-in settings
– Favorite folder add/remove
– Subscribing to new published calendars
– Suggested email replies and attachments
– Roaming signature management
– Email translation
– Weather feature visibility and management within Outlook calendar
– Viewing and editing To Do items, OneNote items, and activity notifications in the Outlook side pane
– Managing connected accounts
– Viewing meeting insights, related content, and meeting transcripts in calendar events
– Managing Outlook groups
– Viewing “Getting Started” tooltips and “What’s New” feature suggestions
– Viewing and editing Loop components.

As a workaround for the signature issue, signatures could be added to email drafts manually, or be applied through the Outlook desktop client.

We believe impact was specific to tenants configured with both split traffic between Evolved Security Token Service (ESTS) and Outlook on the web or IP enforcement conditional access policies.

Final status: Deployment of the fix is complete, and our service telemetry confirms that the affected functions are restored and impact is remediated.

Scope of impact: Some users may have been unable to leverage one or more secondary functions listed in the More info section within Outlook on the web.

Start time: Monday, June 26, 2023, at 7:00 AM UTC

End time: Tuesday, August 1, 2023, at 11:00 AM UTC

Root cause: A recent deployment, intended to resolve an unrelated issue by modifying the authentication pathway leveraged by the affected functionality, introduced an authentication issue that resulted in impact.

Next steps:
– We’re reviewing our Outlook on the web maintenance procedures pertaining to authentication to prevent similar impact in future deployments.

This is the final update for the event.