To import OST files to Thunderbird, you must try the SysInfo OST to PST Converter to import OST files to Thunderbird, Gmail, Office 365, IMAP, and so on in bulk at once. It includes the feature to export OST files to numerous kinds of file formats, for example, PST, PDF, EML, MSG, MBOX, and many more in bulk at once. Users can use this utility on all Windows OS versions, including Windows 11. As well, it assists in maintaining the folder hierarchy as per the actual files. This utility properly skips the same OST files based on distinct criteria throughout the process. It offers the function to preview OST files before implementing the process.