If you want to convert Emails from Thunderbird to PDF, I highly suggest you use the Softaken Thunderbird Conversion Suite. It converts your emails into PDFs in such a short amount of time; this tool is complete conversion software. It converts your emails not into PDFs but into various formats, such as NSF, PST, HTML, EML, EMLX, etc., and doing it manually is such a headache and frustrating. This software works excellently with all versions of Windows. It supports bulk conversion, which is a life-saving feature because we all know how time-consuming it is to convert single files. So, yeah, I think this software is going to work great for your problem.