How to Open MBOX Files in Windows 10/11 – 3 Easy Methods
Updated On - September 28, 2026 by Prakriti | Reading Time: 7 minutes
Quick Answer
To open an MBOX file in Windows, you can import it into Thunderbird or use a dedicated MBOX Converter. If you need to open MBOX emails in Outlook, convert them to PST using the Regain MBOX Converter and then open the resulting PST in Outlook.
MBOX file format is a prominent and widely used file format that more than 20 email clients support. Being used by many email clients, there are a lot of users who have MBOX files, but they don’t know how to open MBOX files in Windows 10 and other Windows OS.
Here, in this blog, we will learn all about the MBOX files and ways to open and view the MBOX file in various ways. Be with the blog till the end and explore all the dimensions.
Detailed information About the MBOX file format:
- MBOX (.mbox extension) is a file format used to store mailboxes in a compressed form. It stores mailbox items in plain text.
- MBOX file is classified into different types: MBOXO (uses the constant sting “???@???”; replacing sender’s email address.
- MBOXRD: it contains the electronic mail messages.
- MBOXCL: For the Unix System V mailboxes.
- MBOXCL2: An MBOX file can’t be converted before attaching to the MBOXCL2.
- Prominent email clients, including Gmail, Apple Mail, Thunderbird, ProtonMail, SeaMonkey, et cetera support MBOX file format and save email data in it.
3 Varified Methods to Open MBOX file in Windows
Method1: Open MBOX Files with Apple Mail
Using Apple Mail, users can also add and open the MBOX file; follow the below-given steps:
- Open the Apple Mail application.
- From the File menu, choose the select Import Mailboxes.

- Out of the available options, select the “Files in MBOX format and click on Continue.
- Now navigate to the MBOX files stored in your local storage and click on Choose.
- Here, Apple Mail will notify you about the added imported MBOX file in Apple Mail.
- Finally, click on the Done.
Method 2: Open MBOX Files with Thunderbird Application
- Open the Thunderbird application, and from the menu, select Account Settings.
- From the Account Settings, from the left pane, click on the Local Folders.
- Under the Message Storage header, using the Browse button, select the folder where the MBOX file is saved.
- After doing all these, restart the Thunderbird, and you will get your MBOX file data in the Thunderbird inbox.
Method 3: Open MBOX Files Using Regain MBOX Converter
No professional wants to bang their head to manage MBOX files, and in many scenarios, when users have multiple MBOX files, it is like walking on eggshells. Manually adding MBOX files in the various email clients requires technical expertise. In most of the cases, the main requirement of users is to open MBOX files in Outlook but Outlook doesn’t support the MBOX files. A lot of users shift to or use Outlook due to its advanced features and compatibility being a Microsoft product. For the same, the Regain MBOX Converter is a mastered utility that is boosted with multiple user-centric features.
- It can add multiple MBOX file formats to convert them to other file formats.
- Users can convert MBOX to PST, EML, MSG, PDF, HTML, and EMLX like prominent file formats.
- This advanced utility can also migrate to Cloud Server like MBOX to Office 365, Exchange Server, Gmail, Yahoo Mail et cetera.
- It properly maintains all the attributes and meta-properties by keeping the MBOX file originality intact.
- Users can simply execute the conversion task in a few clicks.
- Before conversion and after adding the MBOX files, the tool shows a preview of the added MBOX file items.
- After converting to the PST file format, you can simply add the PST files to any Outlook account and view them.
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How to Convert MBOX to PST in a Few Clicks?
- Install and launch the Regain MBOX to PST Converter.
- Now, using the MBOX File Folder button, add the MBOX files to convert. (You can add multiple MBOX files present in the folder).

- Now, you can have a preview of the added MBOX file’s items.

- Make the selection for the resultant file formats. Out of multiple options, click on the PST option. You can also set the size for the resultant PST file using the Split PST option.

- Finally, you will get a file conversion completion.

Wrapping Up:
MBOX file is a widely used format to store mailbox emails, and several email clients support it. A lot of users search for a way to open MBOX files in Windows 10 and other file formats. Here, in this blog, we have explained available ways to open it. Along with the manual ways, a professional tool developed by Regain Software provides an advanced automated way. A free trial version of this software is also available to download which processes the thirty items per folder. Users also get free technical support with this utility.
Frequently Asked Questions
Q1. Is there any limitation with the MBOX size? If not, then will I get the PST file of the same size as it can create an oversized PST issue?
Ans. There are no such limitations on the MBOX file size. Also, no need to worry about the oversized PST issue as this tool offers the Split PST option to set the size for the resultant PST files.
Q2. Are these above-described methods to open MBOX files in Windows 10 applicable to other Windows versions too?
Ans. The MBOX Converter from Regain is compatible with all the versions of the Windows Operating system. On the other hand, manual ways may conflict with old Windows OS if the email client is facing synchronization issues with the OS.
Q3. Can we open the resultant PST file in any Outlook version and account?
Ans. Yes, you can add and open the MBOX file in any Outlook version (from 2003 to the latest that supports Unicode PST) and in any Outlook account.
Q4. I have an MBOX file created by Gmail, and now I want to migrate the data to Office 365. Is creating PST a good option?
Ans. If your ultimate task is to transfer data to Office 365, then instead of converting MBOX to PST, you can directly migrate to Office 365 using this MBOX File Converter Tool developed by Regain Software.
Q5. How can I open an MBOX file in Windows?
Ans. You can open an MBOX file by importing it into Thunderbird or using a dedicated Regain MBOX File Converter tool. For Outlook users, convert the MBOX file to PST and then open the PST in Outlook.
Q6. Can I open an MBOX file directly in Outlook?
Ans. No. Outlook does not natively support opening MBOX files. You can convert MBOX to PST using the Regain MBOX Converter and then access the emails in Outlook.
Q7. Can I open Google Takeout MBOX files in Windows?
Ans. Yes. Google Takeout MBOX files can be imported into Thunderbird or converted to PST, EML, MSG, PDF and other supported formats using an MBOX converter tool.
Q8. What is the easiest way to open MBOX files without Thunderbird?
Ans. A dedicated MBOX converter such as the Regain MBOX Converter can open and preview MBOX emails and export them to commonly used formats.
Q9. Why is my MBOX file not opening in Windows?
Ans. Windows does not provide a native MBOX application. The file may also be very large, damaged, incomplete or incompatible with the application being used. Try importing it into Thunderbird or opening it with a professional Regain MBOX to PST Converter Software.
Q10. Which is better for opening MBOX files: Thunderbird or MBOX Converter?
Ans. Thunderbird is useful for free manual access to MBOX files. A dedicated MBOX Converter is more suitable when you need preview, bulk conversion, PST creation, multiple output formats or migration options.





