If you want to convert PST files into MBOX files then, you can try BitData Migration PST to MBOX Converter Tool that is compatible with all Outlook, Windows OS, and macOS editions. It helps users to convert batch OLM files into MBOX format at once without losing a single bit of database. This utility keeps all email components and folder structure intact during the complete conversion process. Download and try its free demo edition which helps users to convert only 25 items from each chosen folder for free of cost.