Microsoft’s security update has caused search problems in Outlook for Microsoft 365. After installing the update KB5008212, current emails may not appear in the search results.
Microsoft has confirmed the problem, stating that it is working on a solution to fix the issue, and has released a workaround to address it which is similar to an earlier bug.
This workaround involves setting up a registry key to disable Windows Desktop Search and switching to Outlook’s search engine.
To disable the Windows Desktop Search service for Outlook, users should follow a few steps, including right-clicking Start in Windows and then selecting Run.
In the “Open:” box users are advised to type “Regedit” after which they click OK. This will open the registry editor and they will click a subkey in the registry.
Then click Edit > New > Key and name the new key “Windows Search.” Users then select the new “Windows Search” key.
In the next step, click Edit > New > DWORD Value. Type PreventIndexingOutlook for the name of the DWORD, and then press Enter. Right-click PreventIndexingOutlook, and then click “Modify.”
In the Value data box, type 1 to enable the registry entry, and then click “OK.” Finally, Exit Registry Editor, and then restart Outlook.
For more information, read the original story in BleepingComputer.