Convert Thunderbird MBOX file into MS Outlook PST or Office 365

The tutorial summarizes the procedure to convert Thunderbird MBOX files to MS Outlook as well as Office 365. It also mentions the limitations associated with manual conversion approach and suggests a technical solution that allows moving bulk files to PST.

Importing Thunderbird MBOX files to Outlook PST is quite a complex task as it involves a number of manual steps. Thunderbird does not incorporate any straightforward conversion utility. On the other hand, the Import and Export wizard in Outlook 2007 or prior versions does not support MBOX mailboxes. Check out the reasons to move from Thunderbird to MS Outlook/Office 365 in below infographic:

This image has an empty alt attribute; its file name is Reasons-to-Move-from-Thunderbird-to-Outlook.jpg

There are several reasons that call for the need to convert emails from other emailing platforms to Outlook PST. Also, businesses sometimes require exporting Thunderbird MBOX to Office 365 due to the growing popularity.

To export MBOX emails, initially, it requires converting them to EML.

EML is considered an organized file format as it stores one email per file. The entire procedure to convert Thunderbird MBOX emails to Outlook PST can be categorized into three steps:

#1: Convert MBOX files to EML

#2: Transfer EML to Windows Live Mail

#3: Export emails from Windows Live Mail to Outlook PST

Let’s understand the complete Thunderbird to PST conversion process in detail to get a thorough understanding of the entire process.

Step #1: Convert MBOX Files to EML:

The first section describes the process to convert Thunderbird MBOX emails to EML file format supported over multiple emailing platforms.

  1. Launch Mozilla Thunderbird app and navigate to the local folder from where emails need to be exported
  2. Once the emails get enlisted, select emails that you need to export to EML. The app enables to select multiple emails by using Ctrl+A keys
  3. Right click on highlighted emails and select Save As option to store all the files in EML format
  4. The emails can be accessed as EML files by browsing through appropriate folder

Step #2: Transfer EML to Windows Live Mail:

Once the MBOX files are converted to EML format, the next step is to convert the EML files to any of the email programs – Outlook Express, Windows Mail or Windows Live Mail. Here, we will discuss the procedure to convert EML emails to Windows Love Mail.

  1. Launch Windows Live Mail and select the folder that receives EML folder or alternatively create a folder where EML files will be received
  2. In Windows Explorer, open the folder that stores all the EML files
  3. Select all the EML files or the one that you need to convert to PST from Windows Explorer or another file manager. Next, click on the EML file and hold to drag to the mail folder in the Windows Live Mail. Repeat the drag-and-drop procedure for every individual folder that needs to be converted

Note: Manual procedure does not allow batch processing of email messages; however this very limitation can be bypassed using a professional Thunderbird to Outlook conversion utility as it allows moving bulk messages to PST format.

Step #3: Export emails from Windows Live Mail to Outlook PST

Now, when all the email messages are imported to Windows Live Mail, the last step is to export them to MS Outlook to accomplish the conversion procedure.

Make sure that the MS Outlook is installed on the computer. Here, it is important to mention that any image files embedded within the Windows Live Mail messages will be converted as attachments that might appear empty when you attempt to access them. To proceed further with Thunderbird to PST export:

  1. Launch Windows Live Mail, go to File menu, click on Export emails, and then click on Email messages
  2. In the Windows Live Mail Export wizard that appears, select Microsoft Exchange from the enlisted options and click on the Next button
  3. The application will prompt Export Messages dialog box. Click OK to continue
  4. Select Outlook from the enlisted profile names in the Choose Profile dialog box

Note: Usually the Outlook profile is selected by default.

  1. Once the profile is selected, click on the OK button to move further with the export Thunderbird to PST process
  2. Select the folder that needs to be exported to MS Outlook from Windows Live Mail and click on OK. The selected mail folder will be moved to specified MS Outlook profile.


If you are using MS Outlook 2010 or later versions, you can directly export EML messages to PST file format as the latest version of the emailing application supports EML. To do this:

  1. Launch MS Outlook and open the folder that stores EML files in the Windows Explorer
  2. Next, select all the EML files and then drag and drop them to Outlook PST folder

You can also create a new folder in PST mailbox to store all the converted EML files.

Challenges Involved in Manual Conversion Method

You can convert Thunderbird MBOX to PST files by following the above stated manual procedure, but in fact, the entire procedure is complicated as well as time-consuming. Secondly, the procedure does not ensure the integrity of data as the internal structure is put on the stake.

In addition, converting EML files to Windows Live Mail manually requires repeating the same conversion procedure several times for every individual folder. Attachments are displayed as empty after the conversion is completed.

Straightforward Approach to Convert Bulk MBOX Files to PST Mailbox

Stellar Converter for MBOX is a comprehensive solution to convert Thunderbird MBOX to Outlook PST format. The conversion tool allows moving multiple email files from Thunderbird to Outlook mailbox. Batch processing makes export procedure faster and efficient.

Free Download

No compromise is made to any of the components of the email messages. The tool is the most adopted MBOX to PST conversion medium being used as the emails are exported along with attachments and the integral components remain intact.

Apart from Thunderbird, mailboxes from Eudora, Opera, Entourage, AppleMail, Spicebird, Pocomail and other email apps can also be converted to PST directly and efficiently. In addition, the Technical edition of the software allows transferring Mozilla Thunderbird MBOX to Office 365, RTF, HTML, and PDF formats.

  1. Sandra June 6, 2018
    • Eric Simson June 7, 2018

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