Outlook search not working: how to repair the search function?

Outlook search fails almost always due to an incomplete index, not your search term

Classic Outlook doesn't search directly in your mailbox. It relies on the Windows Search index: a background service that catalogues the text of messages, calendar items, tasks, and contacts. As long as that index is complete, results appear in a fraction of a second. If the index is empty, outdated, or damaged, you get no or partial results, even though the mail is simply sitting in your Inbox.

Typical symptoms of a broken index are recognisable: searching yields nothing, only old messages appear, or recent days are missing entirely. Sometimes Outlook displays a message that search results may be incomplete because indexing is still in progress. That isn't a fault, but an indication that you need a little patience. Updating the index takes time, especially after moving your profile or a large import.

Before doing anything drastic: close Outlook completely and restart it. A stalled indexing process sometimes recovers on its own after a restart, and after a major Office update that's often all that's needed. If nothing changes, work through the steps below in order. They run from the quickest check to the most thorough repair, so you don't have to wipe the entire index straight away if a smaller fix solves it.

First determine whether you're running classic or new Outlook

The solution depends on your version. Since Microsoft rolled out the new Outlook for Windows, two programs exist side by side, both called "Outlook" but searching completely differently. In the top right of the window there's a toggle labelled "Try the new Outlook". If it's on, you're running the new Outlook, which searches server-side. If the toggle is off or missing, you're using classic Outlook with the local index.

• Classic Outlook: uses the Windows Search index on your PC. The repairs involving indexing status, the Windows Search service, and rebuilding the index apply here.
• New Outlook: uses cloud search via the Microsoft server. Index repairs have no effect, so skip to the section about the new Outlook.

Making sure which version you're on prevents you wasting hours on a repair that can't help your version. The rest of this article covers classic Outlook first, because that's where most search problems occur and the repairs are most concrete.

Check the indexing status before you try anything else

In classic Outlook, click in the search bar above your message list; the Search tab appears. Choose Search Tools > Indexing Status. A small window opens showing how many items still need to be indexed.

If it says "Outlook has indexed all items" and 0 remaining items, the index is complete and the problem lies elsewhere, such as the search scope or a damaged catalogue. If you see thousands of remaining items, Outlook is simply still busy. Leave the computer on until the counter reaches zero and the results become more complete.

Also check your search scope. Above the results you can choose between Current Folder, Current Mailbox, All Mailboxes, and All Outlook Items. If you're searching a shared or archived mailbox, set the scope to All Mailboxes. A common mistake is searching in Current Folder while the mail you're looking for is in a subfolder or another mailbox. Set the default scope to All Mailboxes via the search options if you often work with multiple accounts; then you won't have to adjust it manually each time.

Set the Windows Search service to Automatic and Active

If the indexing status reports that indexing is paused, the underlying Windows service is probably turned off. Without that service, Windows catalogues nothing, so Outlook searches an empty index. Open the Services overview and check the service.

Windows key + R  ->  type:  services.msc  ->  Enter

Find Windows Search in the list. The status should be Running and the startup type Automatic (Delayed Start). If that's not right, right-click the entry, choose Properties, set Startup type to Automatic, and click Start. If the service is running but indexing is faltering, restart it via right-click and Restart. That forces Windows to reload the catalogue.

In corporate environments, a Group Policy sometimes blocks Outlook indexing. You can recognise that by a registry value that disables indexing. If you have administrator rights, check this key with Registry Editor (regedit):

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Windows Search
Value:  PreventIndexingOutlook  (DWORD)  ->  must be 0

If the value is set to 1, Windows does not index Outlook and searching remains empty. Consult your system administrator before changing it, as the setting usually comes from a central policy that will return after a restart. In that case, the administrator must modify the policy itself; otherwise your change will be reversed each time.

Rebuild the search index in case of damage

If the index is giving unreliable results while the service is running, a full rebuild usually resolves it. First close Outlook. Then open Control Panel and choose Indexing Options. If that icon isn't there, type "Indexing Options" into the taskbar search box.

1. In Indexing Options, click Modify and check that Microsoft Outlook is ticked in the list of locations.
2. Go back and click Advanced.
3. Under Troubleshooting, click Rebuild and confirm.

Control Panel  ->  Indexing Options  ->  Advanced  ->  Rebuild

Rebuilding deletes the existing index and catalogues everything afresh. With a large mailbox this can take hours. Don't switch off the computer during this process and preferably let it work overnight. Search results become gradually more complete as indexing progresses; so don't expect everything back immediately.

If the rebuild doesn't help, a damaged offline data file may be the cause. Close Outlook, go to the %localappdata%\Microsoft\Outlook folder, and rename the .ost file to .old. Outlook creates a fresh file at the next start and indexes it anew. For a POP or PST account, use the Inbox Repair Tool (SCANPST.EXE) instead to check the data file before renaming anything, because a PST contains your only copy of those messages.

With the 'Something went wrong' message, restart the search function

Sometimes Outlook shows a message in the search bar that something went wrong and the search couldn't be completed. That message points to a temporary glitch in the link with the search service, not an empty mailbox. Often a restart is enough to restore the connection.

• Close Outlook completely, wait a few seconds, and open it again.
• Restart the Windows Search service via services.msc as described above.
• Check for pending Windows updates; a half-installed update can break searching temporarily.

If the message returns, repairing the Office installation is the next step. That replaces damaged program files without touching your email.

Run an Office repair if the index keeps faltering

When none of the index steps work, repairing the Office installation mends damaged program files. This approach works for both classic and new Outlook and doesn't affect your messages, because they are stored separately in the data file or on the server.

1. Open Settings > Apps > Installed apps (on Windows 10: Apps & features).
2. Find Microsoft 365 or your Office version, click the three dots, and choose Modify.
3. First choose Quick Repair. If that doesn't fix it, repeat with Online Repair.

The quick repair works offline and takes a few minutes. The online repair downloads the installation again and tackles more stubborn issues, but requires an internet connection and more time. For both versions, close all Office programs first. Microsoft describes this process and search problems in detail in the official guide for search problems in Outlook.

Solve search problems in the new Outlook differently

The new Outlook for Windows searches server-side and completely ignores the Windows Search index. If search doesn't work there, rebuilding the index is pointless. Check the following instead.

• Internet connection: server search requires a connection to Microsoft 365 or Outlook.com. Without a connection you get no results.
• Account status: an expired or freshly added account is sometimes still synchronising. Wait for synchronisation to finish before searching.
• Return to classic: switch the "Try the new Outlook" toggle off in the top right. You'll return to classic Outlook with the familiar local search function.

If that doesn't help, an Office repair is again the next logical step. If you then encounter an activation message, our explanation about Office activation with error 0xC004F074 will guide you through the specific error code and its solution.

Quick checklist to restore Outlook search

Work through these steps in order. Most search problems are solved by step four, so stop as soon as search works again.

If you regularly work with long documents, you'll also want to get the structure in order. See how to set up an automatic table of contents in Word so that large files remain tidy and easily searchable.