I'd similar to offer you one of the most impressive tools Its name is eSoftTools PST to MBOX Converter Software, it can convert PST to MBOX Windows for Free. It shifts speedily and only takes a few easy steps forward to complete. The software can convert PST to MBOX along with all mailbox items, This software export PST emails, contacts, calendars, attachments, tasks, notes, and without affecting the internal data. This software comes with a free test version that recovers and converts 25 items from every folder. It is compatible with full versions of Windows OS and Outlook versions.
Read more:- Convert PST to MBOX
PST to MBOX convert manually:
Step 1: Open Microsoft Outlook.
Step 2: Go to File and click on Open & Export.
Step 3: Click the Import/Export button.
Step 4: Select Export to a file and click Next.
Step 5: Click on Personal Folder File(.pst) and then click on Next.
Step 6: Now in the Export Personal Folders, check if Include subfolders are selected. Hence all the file will be exported.
Step 7: Save the exported file and click on Finish.
This May Help,
Peter