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How to Fix Import MBOX Greyed out in Thunderbird?

Admin ~ March 13, 2025 ~ 6 Minutes Reading

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Mozilla Thunderbird is a widely used email client as it offers free open-source email client and also  known for its flexibility and support for multiple email formats, including MBOX. However, many users face issues Import MBOX Greyed out in Thunderbird error, and it prevent to import into Thunderbird.  It can be frustrating, especially when users want to migrate from another email service to Thunderbird or want to restore Thunderbird old backup.

In this guide, we will explore the possible causes behind this issue, manual approach to fix it, and using Thunderbird Converter to fix Thunderbird import MBOX greyed out and also preventive measures to avoid future occurrences. By following the solution you can easily fix import MBOX greyed out in Thunderbird.

Understanding the Issue

When Thunderbird Import MBOX Greyed out in Thunderbird, it means that the software is unable to recognize MBOX files to import. This can be significant problems for users who need to transfer emails from another client, restore backup or migrate data.

By default, Thunderbird not allows to import MBOX, you need to install Import/Export NG Tools add-ons. However, after add-ons installing, the import option may remain greyed due to version issues, outdated software, or misconfiguration. Now, understand the reasons behind this error as we have explained in the upcoming section.

Possible Causes for Thunderbird Import MBOX Greyed Out

  • Thunderbird doesn’t natively support the MBOX format. Import/Export NG Tools add-ons are required to enable this feature. If the add-on is not installed, outdated or disabled the import option may remain greyed out.
  • Using older versions of Thunderbird may not compatible with Add-ons. If the software is not updated, certain functions, such as Import MBOX file greyed out in Thunderbird.
  • A damaged or corrupted Thunderbird profile can affect the functionality, leading to missing or inaccessible features like MBOX import option.
  • Thunderbird required MBOX files in the correct extension and location. If the MBOX file is corrupted, renamed correctly, or stored in unsupported directory, Thunderbird may not allows to import.
  • If the MBOX file disable read/write permission, Thunderbird may not be able to access and import it, causing the import option to be disabled.

How to Fix Import MBOX Greyed out in Thunderbird Manually?

If the Thunderbird MBOX Greyed out then there are several manual approaches to fix the issue. Follow the instructions to restore the import functionality:

Method 1. Install and Update Import/Export NG Tools Add-ons

Thunderbird doesn’t support MBOX file natively, you must need to install Import/Export NG Tools add-ons:

  1. Open “Thunderbird” and navigate to Tools.
  2. Click on “Add-ons and Themes” and search for Import/Export NG Tools.
  3. “Restart Thunderbird” to reflect the changes.

Method 2. Ensure Thunderbird Updated

  1. Go to Help and click on “Thunderbird”.
  2. If an update is available, “Thunderbird” will automatically install it.
  3. Relaunch Thunderbird application to “Update” it.

Method 3. Enable the Import/Export NG Tools Add-ons

  1. Go to Tools and click on “Add-ons and Themes”.
  2. Search “Import/Export NG Tools” extension and enable it.

Method 4. Check and Update MBOX File Permissions

  1. If the MBOX file has restricted “Permissions”, Thunderbird may not be able to access it.
  2. Right-click on the “MBOX file” and set Properties.
  3. Understanding the security tab, ensure the file is not “Read only” and has granted full permissions.

Method 5. Restart Thunderbird in Troubleshoot Mode

  1. Add-on “Conflict or Setting” may cause the import option to be disabled.
  2. To fix: Open Thunderbird and navigate to “Help”.
  3. Click on “Troubleshoot Mode” and press on Restart to relaunch Thunderbird.

Method 6. Manually Copy MBOX Files to Thunderbird Profile

  1. If the Import option remains greyed out, manually place “MBOX files into the Thunderbird profile”.
  2. Navigate to “Thunderbird profile”: C:\Users\Admin\AppData\Roaming\Thunderbird\Profiles
  3. Open the folder and navigate to “Mail or IMAPMail directory”.
  4. Transfer MBOX file to the relevant folder and Relaunch “Thunderbird”.
How to Quickly Fix Thunderbird Import MBOX Greyed Out Error?

If not fixed manually then we recommend you to opt Thunderbird MBOX Importer as it allows users to directly import MBOX file into the Thunderbird profile and also can import batch Thunderbird or also offer specific selection to save storage space. To use it, you just have to click on the download button and install it on your machine. Now, follow the quick guidelines as we have shared below:

Process to Fix Import MBOX Greyed out in Thunderbird
  1. First, install and run “Thunderbird MBOX Importer” on your system.Launch Thunderbird MBOX Importer
  2. Click on convert emails and “Select files or folders” to browse MBOX files.Browse MBOX Files
  3. Now, choose “Mailbox folders” as you want to import.Select Thunderbird mailbox folders
  4. Select “Thunderbird” in the list of saving options.Choose Thunderbird
  5. Browse advanced filters and press Next to easily “import batch MBOX file into Thunderbird”.MBOX Greyed out in Thunderbird Fixed
Superlative Performance attributes of Thunderbird MBOX Importer
  • It can auto-detect Thunderbird profile to easily import MBOX file into Thunderbird.
  • You can easily migrate Thunderbird emails to Gmail, Maildir, Apple Mail, Outlook and many more.
  • This application can convert individual or multiple Thunderbird profiles without passing any limitations.
  • With this wizard, you can also use filter options such as sender blank address, receiver blank address, root folder, exclude folder and many more.
  • This software can also convert Thunderbird emails as PDF, PST, MBOX, TXT, HTML and 28+ saving options.
Preventive Measures to Avoid Import MBOX Greyed Out in Thunderbird
  • Always use Thunderbird latest version to avoid compatibility issues with add-ons Import/Export NG Tools. Regular update and fix bugs to improve performance.
  • As Thunderbird doesn’t natively allows to importing MBOX files. So, install and enable Import/Export NG Tools and periodically check for updates.
  • Check that MBOX files are not corrupted as Thunderbird not allows to import damaged MBOX file.
  • Some extensions may interfere with Import/Export NG Tools. If issues arise, disable other add-ons temporarily to identify conflicts.
  • Make sure MBOX files have read and write access to prevent Thunderbird blocking and allows to directly import MBOX file without facing greyed out error.
Typical Questions about Thunderbird Import MBOX Greyed Out Error

Does Thunderbird use MBOX format?

Yes, Thunderbird uses the MBOX format to store emails. Each folder in Thunderbird is saved as a single MBOX file, where emails are stored in plain text. MBOX file is widely supported and allows easy migration. However, Thunderbird doesn’t provide built-in options to import MBOX files.

What is the difference between EML and MBOX?

EML files stored individual emails while MBOX contains batch emails in a single file. EML files can be exported by Thunderbird by drag and drop emails. While exported MBOX files contain multiple emails.

How to install Import Export tools in Thunderbird?

To install Import/Export NG Tools in Thunderbird click on Tools and press on Add-ons and Themes. Search for Import/Export NG Tools and click on Add to Thunderbird and now pop appears on display press Ok button.

Final Analysis

Thunderbird is a widely used email client because most users want to import MBOX files into Thunderbird. However, it shows the error “Import MBOX Greyed Out” in Thunderbird, leading users to look for a solution. We hope that after reading this post, you will find the solution and not face similar issues in the future.