How to Split MBOX Files into Smaller Files in 2025 – Easy Tips

MBOX files are the popular format for storing emails often used by Email clients like Thunderbird, Apple Mail, and Postbox. However, as the size of MBOX files increases, they can become difficult to manage, slower to load, and prone to corruption. Split MBOX files into Smaller files can solve this issue and make emails more manageable. In this article, we will explore the reasons for splitting MBOX files and provide a solution to achieve it. Moreover, experts suggest directly using the MBOX Migrator Tool for faster results.

Why Split Large MBOX Files into Smaller Size File?

Let’s discuss the numerous reasons behind splitting large MBOX files:

• Large MBOX can slow down email clients, making them harder to navigate.
• Splitting reduces the likelihood of losing data due to file corruption.
• Smaller files are easier to backup and share if needed.
• Some systems have file size limits, requiring smaller files.

How to Split MBOX Files into Smaller Files?   

Splitting MBOX Files is essential to effectively manage the data for long-term preservations. Therefore, here we will explore the different best tools and methods to split large MBOX files. When users use email clients like Thunderbird, Apple Mail, or Google Takeout subsequently, they can easily use manual methods. However, if users don’t use email clients then, they directly use professional tools for reliable output.

How to  Divide Large MBOX Files Using Dedicated Software 

MCD MBOX Migrator Software is an efficient and versatile solution to convert large MBOX files into smaller parts. It Converts MBOX files into numerous formats such as PST, EML, EMLX, etc. Additionally, also helps to import into different email clients including Thunderbird, Apple Mail, Yahoo, Office 365, etc. This software is highly compatible with many MBOX files simultaneously without data loss. Furthermore, this tool provides more advanced features that make user data more manageable.

• Options to remove duplicate emails based on To, From, Subject, and Body.
• Allow users to preview the content of MBOX files before conversion.
• Saves the attachments separately while converting MBOX to PST.
• Compatible with all Windows versions including Windows 11.

A Step-by-step guide to how to use it: 

MBOX files are not directly split MBOX file into multiple smaller files but, we have alternate methods to split MBOX files. First, users migrate MBOX files into PST format using this software which also provides an option to split the resultant PST file in the conversion process. 

Follow the below steps to execute the process for split MBOX file into parts :

1. First, launch the MBOX Migrator Tool as an administrator.
2. Click on the Continue button to start the process.
3. Now, choose Add File or Add Folder to pick MBOX files and click Open.
4. After that, preview the file content, select the files, and click Next.
5. Select the Save as option as PST from the drop-down list.
6. Now, choose Split Resultant PST size based on your need.
7. Additionally, apply additional features and provide the Destination Path.
8. Lastly, click on the Convert button to begin the conversion process. 

Method 2: Manual Method to Split MBOX Files into Smaller Files 

If users have an email client or text editor like Thunderbird and EditPad Pro subsequently, they can use manual methods. 

A Step-by-step procedure to manually perform this conversion:

1. Firstly, create two copies of the MBOX files.
2. Open one of those copies with any Text Editor.
3. Now, click in the middle of the MBOX file.
4. After that, search for the Header name and Message ID.
5. Once found, scroll to the end of the messages.
6. Delete entire messages below that point and Save the file.
7. Now, open the Second copy of the MBOX file.
8. Afterward, search for the unique message ID from where you split the MBOX file.
9. Lastly, delete all the messages above the Message ID and Save it.

Limitations of the Manual Method

• The manual method required a technical expert to perform this operation.
• High chances of data loss, misinterpretations, or corruption.
• It requires more time and does not guarantee successful completion.

Hence, the manual methods contain some limitations and do not give a direct solution to split MBOX files into parts. Therefore, many users prefer professional tools for instant results and to save valuable time.

Conclusion  

Split MBOX Files into Smaller Files is crucial for efficient email management and long-term data preservations. The manual method works well for smaller files or if the users have the patience to handle the process themselves. However, for larger files or quick results, use professional methods. Choose the method that suits your requirements and make sure your email data remains organized, accessible, and secure.

Also Read : Convert MBOX to MSG Format.