Our website provides a free download of DBX to Thunderbird 4.7.3. The actual developer of the program is DBX Conv. The most popular version of the software 4.7. The program lies within Communication Tools, more precisely E-mail Tools.
From the developer:
Make use of DBX to Thunderbird Converter software, it makes the entire process of converting Outlook Express mailboxes into Thunderbird MBOX format lot easier and simpler. With this tool you can Convert DBX to Thunderbird with complete emails elements. DBX to Thunderbird Converter also maintains the attachment embed with the emails during the entire conversion process.
You may want to check out more software, such as SameTools DBX to PST Converter Tool, which might be related to DBX to Thunderbird.