Grab the best solution - PST to MBOX Converter software to import Outlook data files to Thunderbird with attachments. Both individual and technical users can use this conversion application to import Outlook data files to Thunderbird email clients. One can use this tool on any 64bit or 32bit Windows Operating System including Windows Vista, XP, 7, 8, 8.1,10, 11, etc. Without Apple Mail  & Outlook configuration, the software can also backup data from Outlook in Thunderbird. To know how the tool works before purchasing it, you can use its Free Demo Version, which applies to back up the first 25 emails from each PST to Thunderbird without cost.