Reply To: How to Read MBOX Files on PC?

OK, then download ImportExport add-on and follow below steps:

1. Open Mozilla Thunderbird and click on Tools.
2. Select Import/Export Tools >> Import MBOX file.
3. In Files MBOX Import window, select Import directly one or more MBOX files.
4. Click on OK.
5. To move MBOX file with all subdirectories, select Import one or more MBOX files with its subdirectory option and then, click on OK.
6. Browse MBOX files from the location.
7. Click on Open button to import orphan MBOX files to Thunderbird.