[joywilly]

You may use the ImportExportTools NG add-on to import big MBOX files into Thunderbird. First, go to Thunderbird’s “Add-ons and Themes” and install the add-on. Look for “ImportExportTools NG” and set it up. After restarting Thunderbird, make a folder to store the imported emails in. To import MBOX file, right-click the folder, choose ImportExportTools NG > Import MBOX file, and then pick file. Select the “”Import directly one or more MBOX files”. The emails will be processed by Thunderbird and shown. To prevent delays during the import process, make sure Windows has enough resources if the file is particularly big.

To easily open MBOX files into Thunderbird then try or go with the BLR MBOX Converter Tool. There are users can download this solution in any Windows OS edition. Get the free demo edition of this tool to learn more features.