Indexing issues in Outlook on Windows 11

To fix indexing issues in Outlook on Windows 11 as of early 2026, follow these troubleshooting steps.

1. Run the Windows Search Troubleshooter

The most efficient first step is to use the built-in diagnostic tool.

Go to Settings > System > Troubleshoot > Other troubleshooters.
Find Search and Indexing and click Run.
Select the box for “Outlook search doesn’t return results” and follow the prompts.

2. Verify Outlook is Included in Indexing

Open the Control Panel and search for Indexing Options.
Ensure Microsoft Outlook is listed in the “Included Locations” column.
If it is missing, click Modify, check the box for Microsoft Outlook, and click OK.

3. Rebuild the Search Index

If search results remain incomplete, the search catalog may be corrupted.

In Indexing Options, click Advanced.
Under the “Troubleshooting” section, click Rebuild.
Note: This process can take several hours depending on the size of your mailbox. Searching may not work until it finishes.

4. Configure File Types for Indexing

Ensure the specific email file extensions are set to be indexed by content.

In the Advanced Options menu of Indexing Options, go to the File Types tab.
Scroll down to find .msg, .ost, and .pst extensions.
Ensure “Index Properties and File Contents” is selected for each.

5. Repair the Office Installation

Corruption in the Outlook application itself can cause indexing failures.

Go to Settings > Apps > Installed apps.
Find Microsoft Office (or Microsoft 365), click the three dots, and select Modify.
Choose Online Repair for a comprehensive fix.

6. Registry Workaround (Advanced)

If local indexing continues to fail after a Windows update, you can force Outlook to use its built-in search service.

Open Registry Editor (search for regedit).
Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Windows Search.
Right-click in the right pane, select New > DWORD (32-bit) Value, and name it PreventIndexingOutlook.
Set its value to 1 to bypass Windows Desktop Search for Outlook.

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