1. Open Outlook.
2. Click on File and select Import and Export.
3. Click on Export to a file and then click on Next.
4. Click on Personal Folder File (.pst) and then click on Next.
5. Click on the top most folder.
6. Please ensure that the Option-Include subfolders- is enabled.
7. Click on Next
8. Click on Browse.
9. Choose where to store your .pst file and then click on OK.
10. Enable “Replace duplicates with items exported”
11. Click on Finish.