Rebuild Outlook Search Index: Step-by-Step Fix

If Outlook search is returning no results, showing outdated emails, or spinning endlessly, the search index is likely corrupted or out of sync. Rebuilding the index forces Outlook to re-scan all your mail items and create a fresh, searchable catalog. This guide walks you through the process on Windows (Outlook 2016, 2019, 2021, or Microsoft 365). You’ll need to be signed in to Windows with an account that has administrator privileges, because the indexing service is a system-level component.

What You’ll Need

Windows administrator account access
Outlook closed (or at least not actively used during the rebuild)
Patience – the rebuild can take anywhere from 15 minutes to a few hours depending on mailbox size

Step-by-Step

Close Outlook completely. Make sure it’s not running in the background. Check the system tray (bottom-right corner) for the Outlook icon, right-click it, and choose Exit.
Open Windows Settings. Press Windows + I to open Settings.
Go to Search settings. In Windows 10, click Search then Searching Windows. In Windows 11, click Privacy & security then Searching Windows.
Open Indexing Options. Scroll down and click Advanced indexing options (Windows 10) or Advanced indexing options under “Related settings” (Windows 11). This opens the classic Control Panel dialog.
Click “Advanced” in the Indexing Options dialog.
Go to the “Index Settings” tab. Under “Troubleshooting”, click Rebuild.
Confirm the rebuild. A warning will appear saying that the index will be rebuilt from scratch. Click OK.
Wait for the rebuild to complete. The Indexing Options dialog shows the number of items indexed and the current status. It will say “Indexing complete” when done. You can continue using your computer, but Outlook search will be incomplete until the rebuild finishes.
Open Outlook and test search. Once indexing is complete, launch Outlook and try a search. If it still doesn’t work, proceed to the Troubleshooting section below.

Common Mistakes

Not closing Outlook before rebuilding. Outlook holds locks on its data files; if it’s open, the indexer may skip items or fail to start.
Rebuilding the wrong index. Make sure you’re rebuilding the Windows Search index, not the Outlook “Search Index” from within Outlook (which is a different, older feature). The steps above are for Windows Search.
Assuming the rebuild is instant. Large mailboxes can take hours. Don’t cancel it prematurely.
Forgetting to check if indexing is paused. Windows sometimes pauses indexing when you’re on battery power or when the system is under load. Check the Indexing Options dialog for a “Paused” status.

Tips

Let it run overnight. If you have a large mailbox, start the rebuild before you leave work or go to sleep, and leave your computer on.
Keep Outlook closed during the rebuild. This ensures all items are indexed without interference.
Add Outlook to the indexed locations. By default, Outlook data files (.pst/.ost) are included, but if you moved them to an external drive, you may need to add that drive to the indexed locations in Indexing Options.
Update Outlook. Make sure you have the latest updates installed, as Microsoft often fixes search-related bugs.
Use the “Search Tools” in Outlook. After the rebuild, if search is still slow, try narrowing your search with filters (e.g., from a specific sender, date range) to get quicker results.

Troubleshooting

If the rebuild doesn’t start or gets stuck:

Restart Windows (not just Outlook) and try again.
Check if the Windows Search service is running: Press Windows + R, type services.msc, press Enter, find “Windows Search”, and ensure its status is “Running”. If not, right-click and start it.
If the service won’t start, run the Windows Search troubleshooter: Settings > Update & Security > Troubleshoot > Additional troubleshooters > Search and Indexing.

If search still returns no results after the rebuild:

Verify that Outlook data files are actually indexed. In Indexing Options, click “Modify” and ensure your Outlook data file location (often under %LocalAppData%\Microsoft\Outlook) is checked.
Repair your Outlook profile: In Outlook, go to File > Account Settings > Account Settings > Data Files tab, select your account, and click “Repair”. This can fix corrupted data files.
Create a new Outlook profile (Control Panel > Mail > Show Profiles) and set it as the default. This is a more drastic step but often resolves persistent search issues.

If indexing keeps stopping or shows “paused”:

Disable the “Pause when on battery” option in Indexing Options > Advanced > Index Settings > “Pause indexing when on battery power”.
Check for disk space issues – the index can take up several gigabytes. Ensure you have enough free space on the drive where the index is stored (usually C:\ProgramData\Microsoft\Search).

Frequently Asked Questions

Will rebuilding the index delete any of my emails?

No. Rebuilding the index only deletes the search catalog, not your actual emails. Your messages remain intact in your mailbox.

How long does the rebuild take?

It depends on the size of your mailbox and the speed of your computer. A typical mailbox (a few GB) can take 30 minutes to an hour. Large mailboxes (50+ GB) can take several hours.

Do I need to rebuild the index if I’m using Outlook on a Mac?

No. This guide is for Windows. On Mac, Outlook uses Spotlight for search, and you can rebuild the Spotlight index via System Preferences > Spotlight > Privacy, then add and remove your hard drive to force a re-index.

Why does Outlook search work in the “Current Mailbox” but not “All Mailboxes”?

This often means that some of your mailboxes (e.g., an archive or secondary account) are not indexed. Check that all relevant data files are included in the indexed locations as described above.

Can I prevent this from happening again?

Regularly updating Windows and Outlook helps. Also, avoid moving your Outlook data files to network drives or external USB drives, as these are often excluded from indexing or cause the indexer to fail.

Is there a way to rebuild only the Outlook index without affecting other Windows search?

No, the Windows Search index is shared. Rebuilding it will re-index all locations, not just Outlook. However, you can limit the indexed locations to only what you need, which speeds up future rebuilds.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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