For quick conversion, use the MBOX to PDF Converter for Mac. Add MBOX files and convert them instantly. Apply different features to convert attachments along with the mailboxes. If required, you can use the MBOX Viewer to read the file before converting.
However, you can directly use the Apple Mail Converter to convert the emails to PDF format from the default location of the Mac Mail. Mac users can use this tool for quick conversion without the need to extract the files.

Read More: https://www.macsonik.com/mbox/pdf/