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How to Resolve Import MBOX Greyed Out in Thunderbird?

Bhawna Barwal | email conversion file conversion how to software technology | 4 minutes read | Last updated on May 22nd, 2025,

Overview

Want to fix issue “Import MBOX Greyed Out in Thunderbird”? Then the complete guide on this issue is here. We will discuss some beneficial methods that can actually make you capable to get rid of issues like these.

Thunderbird is a free open-source email client and is well-known for its versatility and support for several email formats, including MBOX, EML, etc. It is a popular email client. But many users encounter problems like Thunderbird error issues “Import MBOX Greyed out” which prevents users to import into Thunderbird.  It is so annoying encountering these kinds of errors, it makes hindrance in switching for one email client to Thunderbird. Also, it restricts to restore or backup Thunderbird data. As we know, Mozilla Thunderbird does not support to import MBOX by default. It is required to install Import/Export NG Tools Add-ons feature. There can be multiple factors behind the issue of importing MBOX, after installing add-ons like not updated Thunderbird, misconfiguration, etc. Now let’s understand the reasons why this inaccuracy occurs in the next segment.

Let’s Fix Issue “Import MBOX Greyed Out in Thunderbird” Manually

There are different approaches that support resolving such issues let’s discuss them below:

Update Import/Export NG Tools Add-Ons Feature

We are quite aware MBOX format does not support by Thunderbird email client by default. It is essential to install, activate Import/Export NG Tools add-ons features. And for this you need to follow below mentioned steps:

  1. Open Thunderbird email client on your system.
  2. Now click on the Tools option.
  3. Thereafter click on the “Add-ons and Theme”.
  4. Search Import/Export NG Tools.
  5. Then restart your Thunderbird email client to see changes.

Copy MBOX Items to Thunderbird Profile

Users can manually copy & paste MBOX files to Thunderbird profile.

  1. Go to Thunderbird Profile.
  2. Open folder and go to “Mail or IMAPMail directory”.
  3. And migrate required MBOX file to the folder.
  4. Lastly reopen your Thunderbird email client.

Restart Thunderbird App as Troubleshoot Mode

Import option may disable due to Add-ons Conflict or Settings. Now let’s see how to overcome this:

  1. Start Thunderbird app.
  2. Go to Help. Then click on the “Troubleshoot Mode”.
  3. Now restart Thunderbird email client.

Enable Import/Export NG Tools

  1. Open Mozilla Thunderbird and click on the Tools.
  2. Then, Add-ons and Themes option.
  3. Now enable Import/Export NG Tools extension after searching.

Update Thunderbird Email Client

  1. In Thunderbird, go to “Help”.
  2. And press on the Thunderbird.
  3. If there is availability of update then it will install it automatically.
  4. Now reinstall Thunderbird app and Update.

Overlook Permissions

  1. Thunderbird cannot access MBOX, in case MBOX restricts Permissions
  2. So, you must right click on the MBOX file then set properties accordingly.
  3. Now grant permissions and do not let file as “Read Only”.  

Quick & Easy Way to Tackle “Import MBOX Greyed Out in Thunderbird”

BitData Migration MBOX Converter – it is a practical solution to migrate MBOX files to Thunderbird. It provides option to migrate bulk MBOX data directly into Thunderbird app at once. And this tool supports migration of all variants of MBOX like MBS, MBX, MBOXO, MBOXCL, etc. This utility enables to convert MBOX file which can be extracted from email clients Apple Mail, Opera Mail, Thunderbird, Eudora, Entourage, etc. The app can simply be interpretable without any technical knowledge. Users have option to download this finest solution on Windows and Mac Operating Systems. And the demo facility of this application is also applicable for 25 emails of MBOX migration.

win download buynow

mac download buynow

How Does Software Work?

Follow few simple instructions to get your query resolved:

Step1: Download, install MBOX to Thunderbird Converter on PC.

Step2: Choose appropriable option to upload MBOX files like Select Files and Select Folder.

Step3: Now preview selected MBOX emails.

Step5: Choose required saving option such as Thunderbird.

Step6: Lastly add destination path and click on the Convert button to start migration.

Read more:

How to Repair Thunderbird Profile

Benefits of Automated Software

  • It simply makes MBOX files accessible in Thunderbird email app without any issue.
  • The software does not have any restriction on size and quantity of emails.
  • Support unlimited MBOX migration at single click.
  • Keep the original component of MBOX emails same during the migration.
  • Such an effortless mechanism to migrate MBOX data, does not demand technical skills.
  • Provide various saving options for exporting MBOX like PST, PDF, MSG, CSV, etc.
  • It also supports migration from MBOX to Gmail, Outlook.com, Office 365, Yahoo, and many more.
  • The tool gives option to locate resultants accordingly and also shows migration status.

Let’s Sum Up

Users can follow this above mentioned proper guide that explains on how to resolve “Import MBOX Greyed Out in Thunderbird”. There were several manual solutions and one automated solution discussed. And users can try any method according to their requirements. If users want to go with the software solution they can use it on Windows OS (Windows 11, 8, 8.1, 10, XP, 7, Vista, etc.) and Mac OS (Monterey, Big-Sur, Catalina, Mojave, Yosemite, etc.). And free demo version of the software is there to help you overlook the efficiency in advance.