I am currently using Mozilla Thunderbird as my primary email client and have accumulated a large number of important emails over the years. For record-keeping, legal documentation, and offline sharing purposes, I now need to convert these emails into PDF format. The main challenge I am facing is that I do not want to convert emails one by one, as that would be very time-consuming. I am specifically looking for a bulk conversion method that can preserve email content, attachments, formatting, and metadata such as sender, receiver, date, and subject. Is there any reliable manual method or trusted third-party tool available that allows bulk conversion of Thunderbird emails to PDF efficiently?