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Fix Outlook Web Emails Reverting to Unread and Flagged
Question details
Users need to resolve an issue where messages in Outlook on the web automatically return to an unread and flagged state even after they are marked as read and the flags are removed.
- Product
- Outlook on the web
- Device & OS
- not provided
- Scenario
- Managing inbox messages and attempting to clear flags or mark emails as read.
- Observed behavior
- Emails revert to their previous unread and flagged states shortly after the user updates them, failing to sync the new status.
Verify that your internet connection is stable and ensure you are using a supported, updated web browser before attempting to troubleshoot synchronization issues.
Clear Browser Cache and Restart Outlook on the Web
Clear corrupted site data to resolve synchronization glitches caused by residual bugs from Microsoft service incident EX545580.
This behavior is often linked to a known Microsoft 365 service incident affecting flag states in Outlook on the web. Once Microsoft deploys a fix, locally cached data can sometimes prevent the solution from taking effect immediately.
Click your profile picture in the top-right corner of Outlook on the web and select 'Sign out', then close the browser tab.
Open your web browser settings (usually found by clicking the three dots in the upper right corner) and navigate to the 'Privacy and security' or 'History' section.
Select the option to 'Clear browsing data'. Ensure that 'Cached images and files' and 'Cookies and other site data' are checked, then click 'Clear data'.
Relaunch your browser, navigate back to Outlook on the web, sign in, and attempt to unflag or mark an email as read to see if the status saves.
Escalate via a Microsoft 365 Service Request
If the problem continues after standard troubleshooting, the issue may require intervention from Microsoft support.
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Frequently Asked Questions
Why do my read emails keep showing as unread in Outlook on the web?
This is typically caused by browser caching issues, server synchronization delays, or Microsoft 365 service incidents (such as EX545580) temporarily preventing status updates from saving to the cloud.
How can I check if there is a Microsoft 365 outage affecting Outlook?
Microsoft 365 tenant administrators can check for active outages by logging into the Microsoft 365 admin center, navigating to the 'Health' section, and viewing the 'Service health' dashboard for known incidents.
Will using a different web browser temporarily fix this issue?
Yes, if the issue is strictly related to a corrupted cache in your primary browser, logging into Outlook on the web via an alternative browser (like Edge, Chrome, or Firefox) or using an Incognito/Private window can bypass the problem.
Can inbox rules cause my emails to revert to unread?
While uncommon for reverting statuses on existing emails, conflicting inbox rules or active third-party add-ins can sometimes interfere with email states. You can test this by temporarily disabling active rules in your Outlook settings.
