Hi,
Thanks for sharing this helpful and useful information. A few days ago, I was also searching for a solution to print MBOX to PDF format with their attachments. Then, through Google Search, I have come across an informative blog which describes the Manual Approach in order to save Thunderbird mail as PDF.

Please Read Here: http://freefileopener.blogspot.in/2018/03/save-thunderbird-mail-as-pdf.html

But, if you want to batch print MBOX to PDF without Outlook in no time, then you can simply use SysTools MBOX to PDF Converter Software.