Search in Outlook has long had problems, especially for POP and IMAP users – specifically, no search results were returned. The latest problem affected some users beginning with version 16.0.9001.2171. While most affected users used either POP or IMAP accounts, some Exchange users also had no search results returned.

To make search work, users needed to disable Windows Desktop Search in Outlook and fall back to Outlook’s slow, native search.

There is now a solution, one that I’m hoping will solve the search problems once and for all.

If you set the registry key to disable Desktop Search, delete the PreventIndexingOutlook value from HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Windows Search

If you don't want to edit the registry yourself, you can download and run this ready-to-use reg file to delete the value: Remove-PreventIndexingOutlook

To quickly find a registry key, copy and paste the registry path in the address bar at the top of the editor in Windows 10 then press Enter to jump to it. You don't need "Computer\", just HKEY and what follows it. If the key does not exist you'll stay on the current key (you will not receive an error message).

Outlook 32-bit

If you are using Outlook 32-bit, verify these two registry keys exist:

HKEY_CLASSES_ROOT\Wow6432Node\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Classes\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}

HKEY_CLASSES_ROOT\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}

Outlook 64-bit

If you use 64-bit Outlook, the steps are the same but the keys are different. You'll need to verify these two keys exist:

HKEY_CLASSES_ROOT\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}

HKEY_CLASSES_ROOT\Wow6432Node\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Classes\CLSID\{F8E61EDD-EA25-484e-AC8A-7447F2AAE2A9}

For more information on this bug, see No search results for POP/IMAP accounts

Search Problems 2017

This was fixed as of build 7870.2031. After updating the Office installation, you may need to rebuild the search index.

Outlook 2016 users are discovering that after updating to builds 7870.2020 and higher, search stops working for POP accounts and PST files.

To revert to the previous working version follow these steps:

1. Close Outlook.
2. Open a command prompt using Run as Administrator
   
3. Run this command (Copy then right-click to Paste in the Command Prompt window):
   cd %programfiles%\Common Files\Microsoft Shared\ClickToRun
   
4. Then this one (copy and paste):
   officec2rclient.exe /update user updatetoversion=16.0.7571.2109
   
5. It will take a few minutes or so for Office to download and replace the older updates
   
6. Re-open Outlook and click File, Office Account and set Update Options to Disable Updates
   
7. Add an appointment on your calendar for a month or more out to remind you to re-enable updates.
   

For more information on reverting Office 2013 and Office 2016 to older builds, see Uninstall Updates in Office 'Click to Run'

Uninstall Updates in Office 'Click to Run'

Disable Instant Search

You can disable Instant Search in Outlook from the Options dialog or using a registry key. Keep in mind that if you disable Windows Search and only use Outlook built-in search to perform the search. Search will be very slow with this key enabled.

From the File, Options dialog, select the Search page and click on Indexing Options. Click the Modify button and uncheck Microsoft Outlook from the list then click OK.

To use the registry method, press Windows key + R to open the Run command. Type regedit in the Open field and press Enter. Browse to the Windows path, right click and choose New > Key, naming the new key Windows Search. Right click again and choose New > DWORD. Name it PreventIndexingOutlook and set the value to 1.

You may need to reboot the computer.

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Windows Search
DWORD: PreventIndexingOutlook
Value: 1