In present arena, Emails are considered to be as the best platform for cross-connection between organizations. As, the popularity of the digitization is increasing as a result there are so many email clients available in online market. Outlook and Thunderbird are two such platforms and both the email client store their respective data in different file formats. Outlook supports PST whereas Thunderbird supports MBOX file format. In order to maintain the continuity of the work sometimes in different live scenarios the need to migrate Outlook to Thunderbird arises. In the following write-up, we will discuss why & how to convert Outlook PST file to Thunderbird MBOX format. Let’s us discuss, why user would migrate Outlook to Mozilla Thunderbird email client.

Need to Transfer Outlook PST File to Thunderbird Windows

Thunderbird provides many remarkable offers like advanced message filtering, saved search folders, quick search, message grouping, etc. Therefore, a user can think to migrate Outlook to Thunderbird. Also, as mentioned above, both email clients supports different file format. So, sometimes the need of the migration arises. Consider the following query to understand the need of shifting Outlook PST file to Thunderbird.

“I am using Outlook for the management of emails. I have received a mail from a my senior in MBOX file format. As the matter of fact, that Outlook does not supports MBOX file. So, I want to know that how to import Microsoft Outlook PST file to Thunderbird (.mbox) format?”

How to Migrate PST to Thunderbird MBOX File Format

To move Outlook data file (.pst) to Thunderbird, you need to first convert PST to MBOX file. In the following section we will going to discuss the methods for the migration:

For Single Machine

  • Firstly, go to start >> Default Programs >> Set your default program. After this, choose Outlook from the given options and click on the button of “Set this program as default”
  • Now, the next thing you need to do is to run Thunderbird and go to the option of “Tools” and then, click on “Import”.
  • Select radio button, which is next to “Mail”, then click on “Next”. Now, choose Outlook from given options and click on “Next”. Once you done that, click on “Finish” to import.
  • To proceed further, follow the same steps and this time choose “Address Books” or any item, which you want to import from Outlook to Thunderbird.
  • Now, go back to Default Programs widow once again. Open it and select Thunderbird and then, select “Set this program as default”

From One System to Multiple System

  • Install Thunderbird to the same system where Outlook is running.
  • Close Thunderbird programs.
  • Now, go to Start button then type %APPDATA% in the search box and choose the folder namely “Roaming”.
  • Now, connect an external device to USB port. Then, make a right-click in Thunderbird folder in the window of Roaming and also, tap “Send to”. Select the USB device and import all the data.
  • Connect the USB device in the same system where Thunderbird program is installed. Open, USB device make a right-click on the folder of Thunderbird and select the option of “Copy”.
  • Again to Start option and type %APPDATA% and select “Roaming” folder. Then, remove Thunderbird folder, which is there and “Paste” the selected copy to Roaming folder.
  • Finally, you see all the Outlook information wherever you launch the Thunderbird.


There are certain limitation in this given manual methods like:

  • This method does not allow to move Outlook contact to Thunderbird.
  • This manual method is slow and you can lose the data due to any wrong step.

Trouble Free Way

To migrate Outlook PST file to Thunderbird users can opt for a trouble free way. They can use a well developed software namely Outlook to MBOX converter tool. Using this software users can convert PST files into MBOX format. This software gives the data in its original form. To move Outlook PST file to Thunderbird users need to follow these mentioned steps:

Step 1: Download and Launch Tool

  • Firstly, click on Start menu >> All programs >> Outlook to MBOX Converter. Outlook to MBOX utility appeared.
  • Now, click on the tab namely “Open” to proceed further.

Step 2: Choose PST File or Folder(s)

  • Now, click on Browse and select location of PST file.

Step 3: Select desired PST path

  • Choose PST file you want to convert into MBOX format.

Step 4: Choose Location of Destination

  • Select the location where you want to save the files after conversion.

Step 5: Give Destination Path

  • Now, click on Browse and choose the location where you want to save PST files.

Step 6: Maintain Hierarchy of Folder

  • Once you define the destination path now, you need to select from the given options to maintain folder hierarchy.
  • Keep folder in the same order as the previous email client by clicking on “Yes” or “No”.

Step 7: Export PST in MBOX

  • Click on “Export” and start the process of migrations.
  • After this, when the migration is done you will see message box showing completion. It will also show the path of the converted PST file.

Step 8: Count Details

  • Once the process is completed you will the count details and you need to press on “OK” when the process is completed.

Step 9: Check Migrated File

  • Navigate to that location where you have saved all the converted Outlook files into MBOX. You can see the Output MBOX file.


Every organization uses different platforms to maintain the continuity of the work. As we have discussed in the above section, sometimes users need to move from Outlook to Thunderbird email client. We have also discussed, some manual methods of PST to MBOX conversion. Users can go for either of the ways as per their requirement.



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