Recommended Tools for Bulk MBOX File Conversion

I am currently dealing with multiple large MBOX files that need to be converted into other formats (like PST, EML, or PDF) for migration and backup purposes. The total data size is quite large, so I am specifically looking for tools that support bulk MBOX file conversion without compromising data integrity, folder structure, or attachments. Can anyone recommend reliable and secure tools for bulk MBOX conversion? It would be helpful if the tool supports batch processing and maintains email metadata (To, From, Subject, Date, etc.).