If you are looking for a simple solution to convert PST to MBOX, I recommend you to use KDETools PST to MBOX Converter. Hope the information provided will help you.

Real estate:

1. Transfer multiple PST items to MBOX, Office 365, Exchange Server,

2. Easy support for ANSI and UNICODE formats.

3. Support without installing MS Outlook.

4. Convert any file size.

5. Corrupted PST files are also restored.

6. Support all Windows versions like 10, 8, 7, XP.

CLICK HERE MORE INFO:  http://www.howtosol.com/products/pst-to-mbox-converter.html