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How to Compress MBOX File and Reduce Its Size?

Published By Nilesh Kumar
Debasish Pramanik
Approved By Debasish Pramanik
Published On May 5th, 2023
Reading Time 7 Minutes Reading
Category MBOX File

MBOX is a popular file format used by email clients to store and organize email. However, over time, these MBOX files can grow in size and take up valuable storage space on your computer or email server. This can slow down your email client and make it difficult to find specific messages. To solve this problem, you can compress MBOX file to reduce its size and free up storage space.

In this article, we will discuss the benefits of compressing MBOX files and provide detailed instructions on how to do it. We will also explore some of the best tools and techniques to reduce MBOX file size.

Why Reduce MBOX File Size? Importance of Compression

MBOX files are commonly used by email clients to archive email messages. However, over time, these files can grow in size and take up a lot of storage space on your computer. This is where compressed MBOX files come into play. By compressing MBOX files, you can reduce their size and free up valuable storage space on your computer.

Compressing MBOX files has other benefits as well. It can help improve the performance of email clients because it reduces the amount of data that needs to be processed. This can lead to faster email searches and faster email load times. Also, compressing MBOX files makes it easy to transfer or backup email data.

In short, compressing MBOX files is important as it saves storage space, improves the performance of email clients, and makes the process of transferring or backing up email data easier. So, if you haven’t already, consider compressing your MBOX files now to get these benefits.

Top 5 Ways to Compress MBOX File

There are several effective ways to reduce MBOX file size and free up valuable storage space on your computer. Here are the top 5 ways to compress MBOX files:

By following these top 5 ways to compress MBOX files, you can reduce their size and free up valuable storage space on your computer. So, let’s get to know them below.

#1 Delete unnecessary emails

The first step in compressing MBOX files is to delete all unnecessary emails that you no longer need. This will reduce the overall size of the MBOX file and make the compression easier.

  1. Open MBOX file in a supported email client like Thunderbird.
  2. Choose redundant emails and other unnecessary messages.
  3. Press the Delete key to remove attachments from MBOX file.

#2 Archive old emails

Another way to compress MBOX files is to archive old emails that you don’t need to access often. This will move those emails into a separate file, thus freeing up space in the MBOX file.

  1. Open your email client and locate the MBOX file containing the emails you wish to archive.
  2. Create a new folder on your computer where you want to store archived emails.
  3. Select the emails you want to archive and drag them into the new folder you created.
  4. Now remove them from email clients to reduce MBOX file size.
  5. Compress the folder containing your archived emails using a tool like WinZip or 7-Zip.
  6. Store the zipped folder in a safe place, such as an external hard drive or cloud storage service.

#3 Use an MBOX compression tool – Recommended

There are several compression tools available that can compress your MBOX file and reduce its size. These tools work by compressing the data in your file, making it smaller and easier to store. We recommend downloading the following software to get the job done. It can remove attachments to reduce the size as well as extract MBOX attachments to specified location.

Download Now Purchase Now

How to Compress MBOX File Quickly

  • Run MBOX Compress software on your system.
  • Click on ‘Add File’ button.
  • Select one or more MBOX files you want to compress.
  • Choose whether to remove attachments or save them.
  • Apply date and file filters on MBOX file.
  • Click ‘Next’ to compress MBOX files successfully.

1- Launch MBOX Compress software on your computer.

start mbox compress tool

2- Select the type of file format (MBOX/MBS/MBX).

choose the mbox file type

3- Click on Add File to choose the MBOX file you want to compress or search your computer for MBOX files using the Search button.

either add mbox file or search mbox file

4- Choose whether you want to remove attachments permanently or remove them from the file but save them on your computer.

remove or save attachments

5- In the next screen, make sure to give out the destination location where you want to save the new MBOX file after compression.

change destination location

6- Go to the next screen to include/exclude attachments according to selected filters: Date filter and File filter.

choose filters for mbox file attachments

7- Finally, click the Next button to start compressing MBOX file live.

reduce mbox file size

You can check the different reports regarding the process and the compressed MBOX file at the destination location.

#4 Split your MBOX file

If your file is too large to compress, you can split MBOX into smaller files manually or by using a tool. This will make it easier to manage and compress each file individually.

#5 Convert to a different file format

Finally, if all else fails, you can convert the MBOX file to a different file format like PST or EML. These file formats are usually smaller than MBOX files, making them easier to store and manage.

Best Practices for Efficient Email Management

Now that you have compressed your MBOX file and reduced its size, it is important to implement some best practices for efficient MBOX email management. Here are some tips to help you manage your email effectively:

  1. Organize your emails into folders: Create folders for different types of emails and organize them accordingly. This will make it easier for you to find a specific email when you need it.
  2. Use filters and rules: Most email clients have filters and rules that automatically sort your mail into folders based on certain criteria. Use these tools to save time and keep your inbox organized.
  3. Regularly delete unwanted emails: Don’t let your inbox fill up with unwanted emails. Regularly delete emails so you no longer need to keep your inbox tidy.
  4. Back up your MBOX: It’s important to back up your emails regularly to avoid losing important data. Use a cloud storage service or an external hard drive to back up your mail.
  5. Use a reliable email client: Choose a reliable email client with the features you need. Look for an email client with good performance, security features, and an easy-to-use interface.

By following these best practices to manage your MBOX emails effectively, you can keep your inbox organized and your emails secure.

Conclusion and Final Thoughts

Compressing MBOX files and reducing their size is essential for efficient email management. By following the top 5 ways to compress MBOX files, you can free up valuable storage space on your computer, improve the performance of your email client, and make the process of transferring or backing up your email data easier. So give them a try and enjoy a faster and more efficient email experience!


How often should I compact my MBOX file?

There are no mandatory rules regarding this. It all depends on how frequently you receive emails and the size of the MBOX file.

How long will the compress process take?

The time required for the process to complete depends on the total size of your MBOX file and how many attachments need to be deleted. For a small MBOX file, it finishes in a few minutes. But an MBOX file that exceeds 10s GB in size requires 10-30 minutes based on the number of attachments.