Many email clients stores emails into MBOX format. If you wants to convert these emails into universally supported PDF format then you can make use of ZOOK MBOX to PDF Converter. This tool allow users to convert emails from MBOX to PDF format with attachments. This tool kept intact all emails formatting and data integrity throughout the conversion process. The tool easily convert MBOX files of all major email clients like Mozilla Thunderbird, Apple Mail, Netscape, Opera Mail, Yahoo Mail and many others. It is completely professional tool thus you can utilize to convert MBOX files to PDF format for bulk conversion.
For more info- https://www.zooksoftware.com/mbox-to-pdf/