Fix Import MBOX file is Disabled in Thunderbird? 2026 Guide

Overview: Fix the “Thunderbird import MBOX not available” issue. A complete solution guide to help individual and professional users in case the MBOX import option is missing in Thunderbird. This write-up lays out step by step instruction you need to follow to enable MBOX import in Thunderbird, and enable bulk MBOX import in Thunderbird. Also, discover a professional tool to safely import large MBOX files in Thunderbird with complete integrity. 

Understanding What “Import MBOX File Is Disabled in Thunderbird” Means

Thunderbird is a desktop email client that works on both Mac and Windows devices. It is widely popular as a free solution to import and export MBOX files.

Understand MBOX File: They are email storage files to hold multiple emails with attachments in a proper hierarchy with attachments. 

Since it is not a native option, do not worry if you find the Import MBOX greyed out or missing in Thunderbird. Importing MBOX in Thunderbird depends on Add-ons, the folder in which you are trying to import, Profile permissions, and Thunderbird version.

Important Note: You cannot directly import MBOX into a pre-defined user/ account folder using Thunderbird. You can import MBOX only inside the local folder that you can further move to the desired location. 

Common Reasons Why Thunderbird MBOX Import is Disabled

It is fairly simple to import MBOX in Thunderbird; however, user ofthe face issues with it at the same time, often due to a lack of technical understanding of the application. 

Knowing the core reason helps to fix the issue faster and correctly import MBOX data in the Thunderbird application. 

• ImportExport NG is not installed. 
• The version of Thunderbird is not compatible with ImportExport NG. 
• Trying to Import in pre-defined user/ account folder.
• macOS / Windows profile permission restrictions. 
• The MBOX file you are trying to import is corrupted. 
• You have a Read-only Thunderbird profile. 

Quick Troubleshooting to Fix Thunderbird Import MBOX Not Available

The “Thunderbird import MBOX greyed out” issues can most likely be fixed natively. 

Here are the multiple fixes you can try out. 

Fix 1: Ensure you have Thunderbird ImportExport NG Add-On 

1. Open Thunderbird. 
2. Click on the Hamburger Menu on the top-right. 
3. Choose Add-Ons and Themes.  
4. See if you already have ImportExport NG. If not, install the Add-On to resolve the MBOX import option missing in Thunderbird issue. 

Fix 2: Reinstall the Thunderbird Application 

Note: Do not worry about data loss when reinstalling Thunderbird, as it stores data locally on Profile folder. It auto-fetches the data back after reinstallation. 

Reinstalling Thunderbird will result in fixing “Thunderbird import MBOX greyed out,” as it fixes the Add-On-related issues and properly reconfigures the profile. It also gives you the latest version of the Thunderbird Application with updates. 

Remember: After this, you will have to reinstall ImportExport NG Add-On to import the MBOX file into the Thunderbird profile. 

Fix 3: Give Thunderbird Required Permissions

If your Mac or Windows OS does not provide your Thunderbird application to import MBOX files, you will find that the Thunderbird import MBOX option is not available. 

Here are the exact steps you need to follow on Windows and MacOS to fix the issue.

Note: Make sure you close Thunderbird following the steps. 

On Windows: 

1. Go to Thunderbird Shortcut and run Thunderbird as Administrator. 
2. Go to the Properties >>  Compatibility tab. 
3. Check. Run this program as an administrator. 

Also, ensure you allow Thunderbird in Windows Security 

On MacOS: 

• Grant Full Disk Access by opening System Settings >> Privacy & Security >> Full Disk Access and add Thunderbird. 
• In Privacy & Security, open Files and Folders. Ensure Thunderbird has access to Documents, Downloads, and Desktop at least.

These fixes can help you import MBOX files into Thunderbird manually by troubleshooting the issue. 

What to do if Thunderbird Import MBOX is Still Greyed Out? 

It can be frustrating if, even after spending time on manual fixes, Thunderbird Import is now working. This is because manual fixes have limited use cases. 

• It will not work if the profile data is corrupted. 
• If the issue is with MBOX files to be imported. 
• Fails with Large or Bulk MBOX Imports.

Skip the Manual Hassle with the BitRecover Professional Solution 

BitRecover Thunderbird Import Wizard is a dedicated tool to import MBOX files directly into Thunderbird without needing any additional add-ons or even depending on the Thunderbird application to the profile on both Mac and Windows device. 

Smartly designed to bulk add MBOX data in Thunderbird, even if “Thunderbird import MBOX not available.” It is secure, fast, and reliable as it preserves folder hierarchy, metadata, and attachments. Download the tool today. As the tool provides a trial edition, users can only import 25 email messages to the Thunderbird email client. To import unlimited Thunderbird email messages, users need to buy a licensed edition.

How to Import MBOX in Thunderbird if Thunderbird MBOX Import is Disabled? Pro Solution 

Using the BitRecovers Pro solution is easy, even for people with limited technical knowledge about Thunderbird. 

1. Launch Mozilla Thunderbird Import Tool and choose one option from Add Files or Add Folders.
2. Choose a folder having multiple mailbox files and click on the Next button.
3. Select specific mailbox files from the software window and click on the Next button.
4. Thunderbird Importer automatically chooses the default TB profile location to store imported mailboxes.
5. Click on the Next button to start the process to import Mailbox to Thunderbird.
6. Now you can see the message of completion, press Ok button to confirm that.
7. At last, start the Mozilla Thunderbird email client and preview the imported data.

Why Choose Bitrecover if Thunderbird Import MBOX is not Available? 

• No add-ons required
• Supports bulk MBOX files
• Handles large mailboxes easily
• Preserves folder hierarchy
• Maintains email metadata
• Secure and offline processing
• Works despite Thunderbird limitations
  

Key Takeaway and Expert Suggestion 

Thunderbird imports MBOX files using Add-ons, profile permissions, and (more importantly) the stability of the user’s profile results in many scenarios where the import process can be unpredictable; manual solutions typically work best, or only, when dealing with small and non-corrupted files. Therefore, when Thunderbird doesn’t offer an additional import option, users should use a third-party tool that captures MBOX content correctly, safely, and completely.