If you want to convert PST to MBOX format, the best tool is eSoftTools PST to MBOX Converter Software. It is efficient. Only a few more steps are needed to make this clear. Both ANSI and UNICODE PST files are approved for conversion. The framework supports both new and older versions of Microsoft Outlook. Both customers have access to the trial version, which allows them to convert up to 25 email objects per folder for free.