How to Open Large MBOX File in Windows and Mac? Top 5 Ways

  

Mark Regan
Published: May 15th, 2025 • 8 Min Read

Do you have multiple data files with the .mbox extension and want to open them to access all your data? If it sounds appropriate, then you are on the right blog. Here we will explain the best methods to open large MBOX files on Windows and Mac machines with or without email services. So, without wasting too much time, let’s start the article.

Understand MBOX File

MBOX files are a standard file format that stores all the data, including email messages and attachments, in a single database. MBOX files are supported by many well-known email clients. However, several different applications allow you to open an MBOX file.

Moreover, there are four types of MBOX files supported by different platforms. Such as MBOXO supported by Eudora, MBOXRD supported by Qmail, Thunderbird, and Netscape, MBOXCL, and MBOXCL2.

Important Note: Download the completely Free open MBOX file tool by BitRecover to open large MBOX files without installing any extra applications. It can even access multiple file data without preserving information.

Free Way to Open Large MBOX Files in Windows

Follow the quickest and simplest steps to open an MBOX file in Windows & Mac machines:

• Step 1: Start the given the solution.
• Step 2: Upload your single or large MBOX files.
• Step 3: Click on any folder and email to preview.
• Step 4: Use the “Search” option to find any email data.
• Step 5: Head to the “Attachments” tab for media.

How to Open an MBOX File in Windows & Mac Machines?

We will access data using Thunderbird, Apple Mail, Chrome, and a free solution for both Mac & Windows machines. All the methods are given below one by one, use them according to your requirements to open large MBOX files.

#1: Open MBOX Files in Thunderbird (For Windows)

Important Note: Install the “ImportExportToolNG” add-ons on your Thunderbird profile to visible the “Import” button.

1. Open the Thunderbird desktop application on your computer.
2. Log in to your account and go to the “File” tab.
3. Choose the “ImportExportTools” >> “Import MBOX Files” option from the list.

   

4. After that, select the “Import Directly One or More Files” and then the “OK” icon.

   

5. Choose the MBOX file you want to open from your computer.

   

6. Click on the “Open” button at the end to open an MBOX file data.
7. And you analyze your MBOX file data in the Thunderbird profile.

   

#2: How to Open an MBOX File in Chrome or Any Browser?

All browsers, including Chrome, support the .html format to open any file data, so first we have to convert MBOX files to HTML format. You can do it by following the linked page, or you can follow the given steps if you have installed a Thunderbird account.

After uploading your data files to your Thunderbird account, follow these steps:

1. Right-click on the imported MBOX file.
2. Again, select the “ImportExportNG” option.
3. Now, choose the “Export All Messages in a Folder” button.

   

4. After that, hit the “HTML Format” option.

   

5. And select any path to save the exported file.
6. Finally, hit the “Export” icon.

Now you can open the exported file in Chrome or any browser.

#3: How to Access an MBOX File in macOS Using Apple Mail?

1. Log in to your Apple Mac Mail.

   

2. Find and select the “File” tab.
3. Select the “Import Mailboxes…” from the list.

   

4. After that, choose “Files in MBOX Format” and then the “Continue” button.

   

5. Locate the path of your .mbox file on the machine.

   

6. Hit the “Continue” button and wait for the moment to upload data, and at last choose the “Done” button.

   

#4: How to Open MBOX Files/Folders in PostBox?

1. Start PostBox >> Navigate to “File Menu” >> Click “Import”.
2. Select the MBOX folder from its path and hit the “Import” button.

How Does the Free Open MBOX File Tool Work? All Steps

1. Download and install the tool on your PC.

   

2. Click on the “Add File” or “Add Folder” button to open MBOX files.

   

3. And then, on the next interface, you can preview all MBOX folders and specify which you want to open.

   

4. After selecting the folder, the tool will show you a complete open of your MBOX data with all details and attachments.

   

Conclusion

In short, opening large MBOX file is not so complex; hence, all you need is proper guidance and easy-to-understand methods. In this article, we have explained how to open an MBOX file in Windows and Mac with multiple different methods.

We described all the methods in a very simple way, but still, users can face challenges like lots of technicalities and time consumption in opening MBOX files manually. However, it is preferred to go for the pro solution to access batch MBOX files at once with attachments peacefully.

Here are Some Users’ Queries

1. Ques: What is the easiest way to preview MBOX files?

   Ans: The BitRecover Free tool is the right and easiest way to open an MBOX file data without leaving any detail with attachments and other media.

2. Ques: Why am I not able to open large MBOX files through other applications?

   Ans: MBOX files are supported by a large number of email clients, but if you need to open an application that does not support MBOX files, you will have to convert it. You can use MBOX Converter to import and save MBOX files in MSG, EML, PDF, Windows Live Mail, Office 365, IMAP Server, Gmail, etc.

3. Ques: I have an MBOX file without any file extension, and I am unable to access the data of this file. Could anyone inform me how I can use it?

   Ans: It might be that your file is corrupted, so first you have to repair your data file and then try to open it.

4. Ques: Hey, I want to convert all my email files to PST format, but your solution is not allow to do it. Please help me to change the extension?

   Ans: Yes, our free tool doesn’t allow to save emails into PST format, so you have to buy the license of the  upgrade version of this tool, which gives you 30+ different saving types including PST, PDF, EML etc.