Method-1: Registry Tweak
1.
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\
or
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Search
2. Press “Windows Search” on the left, then double-click “PreventIndexingOutlook” on the right.
3. If you don’t have “Windows Search,” you can create it by right-clicking “Windows -> Edit -> New -> Key.” Name it accordingly, then create the “PreventIndexingOutlook” value by right-clicking an empty space on the menu on the right and selecting “New -> DWORD Value (32- bit).”
4. Once created, double-click it to adjust the “Base” to “Hexadecimal” and change “Value data” to “1,” then click “OK.”
5. Reboot Computer