Hello,
The Indexed folder that you are looking for is only available in
Windows 8 and 8.1. The option to back up the emails from the
Windows 10 Mail app is by opening them one by one. To do this, you may follow the steps below:
1. Open the Mail application on your
Windows 10 computer.
2. Select the email that you want to save, click the
(three dots)
icon.
3. Click Save As and select the folder location on where you want to save the file, and then click the
Save button.
4. Once you’re done, you may check if you’re able to save your emails on your PC properly.
Keep us updated about your concern for additional assistance.