Try this:
From Outlook's File menu, select Import and export, and then
Export to a file and click next. After that, select Personal Folder
Folder (.pst) and then again next. Select your Personal Folders
folder and then click Include subfolders. After that, you can
select the name of the exported file which will contains everything
in your mailbox (don't bother with the duplicates option).

Now, save this file and when you want to restore your outlook
folders, you will again go to File - Import and Export - Import
from another program or file - Personal Folder File (.pst) and
select your file.

Papastefanos Serafeim
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