How to Merge Multiple MBOX files

There are a number of email clients that support MBOX file format like Mozilla Thunderbird, Apple Mail, Entourage, etc. MBOX is a mailbox file which consists of all the emails from one mailbox in a single file. In Thunderbird like application, a user can configure a number of email accounts. But if there are many accounts and emails, then it would be a better option to merge mbox files in a single file for better searching and retrieving of emails. There are many user queries related to MBOX merging process like:

Hey! I am currently using Thunderbird having 5 email accounts and too many folders in my email client. It becomes difficult for me to search a specific email from all the folders because of duplicity. I need a solution to merge Mbox files so that I can refine my searching of emails. Thanks!”

Need To Combine MBOX Files

There are many reasons to join MBOX files. Some are discussed below:

  • In order to speed up the searching and retrieval process of specific email from the number of folders or accounts, then you should merge them.
  • To use the merged or big file in any other email clients like Outlook.
  • One can remove the duplicate emails or data and increase the free space in a hard drive by merging all the emails in one folder.
  • A user can manage to merge MBOX files in one archive file.

Manual Approaches For Merging MBOX Files

There is a two-step process to combine MBOX files by which a user can merge all his emails.Follow the step1 for mbox conversion & step 2 to join MBOX Files..

STEP 1: Convert MBOX Data file

Since, MBOX file & Outlook belong to two different platforms. MBOX Conversion is really a tiresome task. The manual conversion is really so lengthy that it is practically impossible for a real-world user. In such cases a user can go for any Mbox conversion tool to convert .mbox file to Outlook hassle-free.

STEP 2: Merge MBOX Files

After importing emails in MS Outlook, now you have to perform steps to combine mbox files by creating master archive folder. Follow steps below:

  •  In MS Outlook, create a new PST file that is a Master Archive by clicking on File >> Account settings >> Account Settings >> Data Files.
  •  Now browse the location and create new name for Master archive folder.
  •  Click on File >> Open >> Outlook Data File. Connect your master archive to all the emails imported in the previous step and copy the content to it.
  • Disconnect previous archives and save a new master file in default archiving location by Auto-Archive settings. For that click on File >> Options >> Advanced >> AutoArchive settings.
  •  It can merge MBOX files in MS Outlook in the form of PST file format.

Alternate Method For Combining MBOX Files

Above manual approach for merging mbox files is a time-consuming & confusing process. You need to have Mozilla Thunderbird or any other email client that supports MBOX file format and MS Outlook to import emails and merge them. There is a possibility of data loss as you are dealing with bulk data to merge. An easy solution to merge MBOX files is possible by a third-party tool. The tool has some key features that prevent data loss and helps user to combine mbox files successfully. Follow simple steps in the software to get the results:


  • Click on Start menu, search and launch the tool.


  •  Click on Add File to add multiple .mbox files.

  •  Now select the MBOX supported email application from the list. That email client should be installed on your system.

  • Now select the Default Profile Configured option for automatic configuration and fetching of data or click on the Select file(s)/folder from file system to provide the location of the file by yourself. And then click on Next button.

  • Now browse multiple MBOX file using Folder Mode to combine mbox files.

  • Select your desired MBOX file and click on Open.

  • Now export all the MBOX files in selected file formats by selecting Export All Folder.

  • Click on Export button to start the export process.

  • After clicking on Open Location, you will be able to access your files merged MBOX file in PST format.


To merge MBOX files into one file, you must go through above manual approaches to combine mbox files and an expertise solution. It will save your time and efforts. Through this blog we have discussed methods to deal with a large amount of data in MBOX format & to join mbox files.