most folk install a PDF printer driver and print the emails.

PDF? Really? An odd choice, IMHO.

You generally create PDF by printing to a virtual pdf printer. Some current windows versions have this built in; if not you can look for free or low-cost third-party solutions such as those listed here:

http://helpdeskgeek.com/free-tools-review/7-free-pdf-writers-and-pdf-printers/

If you have a lot to do then a bulk converter might be more suitable.

https://www.coolutils.com/Convert-Thunderbird-email http://www.thunderbird-convert.emltopdfconverter.com/

None of the above are recommendations; just the results of a quick bit of googling.

One add-on that I would recommend is this:

https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/

which includes an export-to-pdf option. It warns you that attachments will NOT be preserved. I think this is entirely reasonable; attachments could be of any conceivable file format and would not be compatible with being stored in PDF format.

Thanks everyone for your quick reply but it didn't worked for my situation. I just found a quick solution from

https://gallery.technet.microsoft.com/MBOX-to-PDF-Converter-bfdd9ab1

which worked for me and I have successfully converted my mbox emails into pdf file format...