Indexing
https://www.lifewire.com/fix-outlook-search-not-working-4177245
MAKE SURE OUTLOOK DATA FILES ARE BEING INDEXED
- Type Indexing Options in the Start Search box or on the Start screen.
- Make sure Microsoft Outlook appears in the Included Locations column of the Indexing Options dialog box.
- Select Modify if Microsoft Outlook is not listed.
- Click the check box next to Microsoft Outlook to select it.
- Click OK.
- Click Close.
REBUILD THE SEARCH CATALOG IF INDEXING REMAINS STUCK
- Type Indexing Options in the Start Search box or on the Start screen.
- Select Modify in the Indexing Options dialog box.
- Clear the check box next to Outlook and click OK.
- Select Advanced to open the Advanced Options dialog box.
- Click Rebuild.
- Click OK.
- Click Close.