Email Sync Problems

Fix Flagged Outlook Email Task Not Completing in Microsoft To Do

Tauseeq Magsi Oct 1, 2026 869 views

Question details

Users are experiencing an issue where deleting a flagged email in Outlook no longer automatically marks the corresponding task as completed in Microsoft To Do.

How to Fix Flagged Email Task Not Completed After Deletion in Microsoft To Do

Product: Microsoft Outlook / Microsoft To Do
Device & OS: not provided
Scenario: Managing tasks created automatically from flagged emails across Outlook and Microsoft To Do integrations.
Observed behavior: The linked task in Microsoft To Do remains active and incomplete even after the original flagged email is deleted or marked as done in Outlook.

Before you start

Ensure your Outlook application is connected to the internet and fully synced with your Microsoft Exchange or Outlook.com account, and check if the issue persists on the web version.

Solution 1Recommended

Report the Outlook-to-To Do Sync Service Bug to Microsoft

Since this is a recognized synchronization backend issue affecting both desktop and web platforms, submitting a detailed report via the Help menu is the most effective way to alert developers for a patch.

This issue typically stems from a backend Outlook-to-To Do synchronization service failure rather than a local app glitch. Because it occurs consistently on the web version as well, clearing local caches or reinstalling the application is unlikely to resolve it permanently.

Open the Help menu

Launch Microsoft Outlook or any Office application and navigate to the 'Help' tab located on the top ribbon.

Access the feedback tool

Click on 'Feedback' or 'Contact Support' from the available options in the Help menu.

Submit reproduction steps

Describe the issue clearly: explain that you flag an email to create a task, delete the email, but the task remains incomplete in To Do. Submit the report so Microsoft engineers can investigate the sync service.

Report the Outlook-to-To Do Sync Service Bug to Microsoft

Manual Workaround: While waiting for a backend patch from Microsoft, you will need to manually open the Microsoft To Do or Planner app to check off and complete the orphaned tasks.

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Frequently Asked Questions

Why did deleting flagged emails stop completing tasks in Microsoft To Do?

This is typically caused by a backend synchronization error in the Outlook-to-To Do service. Changes made in the Outlook client, such as deleting an email, are currently failing to trigger the completion status update in the Microsoft To Do database.

Does this task sync issue affect the older Outlook Tasks view as well?

The issue primarily affects the newer Microsoft To Do application and Planner integrations. The older built-in Outlook Tasks list operates on a slightly different protocol and might still function normally depending on your Outlook version.

Will marking the email as 'Done' instead of deleting it fix the sync?

Not necessarily. Many users have reported that even when marking the email as 'Done' in Outlook, the associated task remains active in Planner or To Do due to the exact same backend synchronization bug.

How can I manage these orphaned tasks in the meantime?

Until the sync service is patched by Microsoft, you will need to manually open the Microsoft To Do app or web interface and mark the affected tasks as completed directly within the app.

Outlook & Email Problems