How to Import MBOX Emails to Mozilla Thunderbird?
With the correct configuration, importing MBOX emails into Mozilla Thunderbird is a fairly simple procedure. First, use Thunderbird's Add-ons Manager to install the ImportExportTools NG add-on. Restart Thunderbird after installation, then right-click on the folder or mailbox where you wish to import your emails. Depending on your preferred folder structure, pick ImportExportTools NG > Import MBOX file. Your MBOX file will be imported straight into Thunderbird after you browse and choose it.
Verify that the MBOX file is correctly formatted and free of corruption. A third-party program like BLR MBOX Converter can simplify and improve the process if you're having trouble with manual import or wish to import several MBOX files at once.

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You can import MBOX emails to Mozilla Thunderbird manually using the ImportExportTools NG add-on, but the process is long and can be confusing if you're not a technical expert. A much easier way is to use a third-party tool like Advik MBOX Converter. This software is beginner-friendly and doesn’t require any technical skills. It can import MBOX to Thunderbird in bulk and keeps all your email details safe during the process.
Steps to Import MBOX to Thunderbird:
Open the tool and add your MBOX file.
Select the mailbox folders you want to import.
Choose Thunderbird as the saving option.
Click the Convert button to start.
That's it! Your MBOX files will be imported into Thunderbird easily.
Try the CubexSoft MBOX Converter for Mac and Windows, a reliable solution to efficiently export MBOX files into multiple formats such as PST, PDF, EML, MSG, and others. The software is compatible with all MBOX-supported email clients, including Thunderbird, Apple Mail, Eudora, Entourage, Opera Mail, and more. Designed with a simple and intuitive interface, it allows both beginners and professionals to operate it effortlessly without any assistance. The tool works seamlessly on macOS and Windows platforms, including the latest Windows 11 version. A free demo edition is also available to experience the software’s features at no cost.