eSoftTools PST to MBOX Converter Software is one of the best solutions to open PST files in Thunderbird. You can export your emails in MBOX format using this advanced feature tool. Users can utilize this tool to optimize their Outlook data. Even non-technical people will find the user interface simple to use. It will be available for everyone to test out for free. You can only update 25 email items per folder at a time in the demo edition, but you may access free technical support at any time.