Mozilla Thunderbird is an open-source application that renders services like email management, RSS Feeds, Junk Filtering, client chat, etc. It provides cross-platform support, which means that the Thunderbird client is free to download and can be installed on all major operating systems like Windows, Mac, Ubuntu, and Linux.

Thunderbird, for sure, is an email client of the modern age, but many professionals nowadays choose to opt. for a more secure and advanced platform like MS Outlook. And users willing to migrate from Thunderbird to MS Outlook have to rely on either a manual approach or automated methods for the MBOX to Outlook PST Converter.

Reasons for Thunderbird to Outlook Migration

There are several governing factors that prompt users to migrate their mailbox data from Thunderbird to Outlook. For instance, many Thunderbird users have continuously reported that they are issues like error messages, frequent deletion of emails, user profile display issues, etc. Thunderbird is a good choice when all you need is an email facility and nothing more; on the other hand, Outlook offers much more than just emails. Outlook has an in-built calendar, Task list, and Contact list. Being part of Microsoft Office Suite, Outlook is much more popular than Thunderbird and consists of enterprise-level features and quality customer support. Outlook supports accounts of POP3, IMAP, or Exchange Server better.

Export Thunderbird Emails to Outlook PST (Windows, Mac, and Linux Versions)

Both Thunderbird and Outlook have entirely different native file formats that don’t facilitate any exchange of data. Therefore, in order to migrate emails from Thunderbird to Outlook, first, you have to convert Thunderbird’s MBOX file to PST format.

Note: The default file format supported by Outlook for Windows is PST, whereas, for Mac, it is OLM.

In the later sections, we have thoroughly elaborated the conversion process for Thunderbird emails to Outlook.

Thunderbird to Outlook Migration on Mac Machine

Suppose you are using Thunderbird and Outlook both on a Mac system, and you want to migrate Thunderbird emails to Outlook for Mac. What are the steps you need to follow in order to do that?

Well, Thunderbird doesn’t provide any inbuilt feature to export its emails to Outlook. Therefore, in order to achieve the migration on a Mac machine, first, you need to convert Thunderbird emails to OLM file format. For that you can use a third-party MBOX file to PST Converter. Though OLM is the native file format for Outlook on Mac, it can import PST files too; thus, you can manually import the converted PST file to Outlook for Mac mailbox without any additional procedures.

Thunderbird to Outlook Migration on a Windows Machine

The most recommended way to migrate Thunderbird emails to Outlook on the Windows environment is to use reliable third-party software to do the conversion task for you. However, you can also opt for a manual approach in case you are not willing to use any third-party Thunderbird to PST converter software.

Thunderbird to Outlook migration on the Windows platform is achieved by implementing these three consecutive steps:

  1. Convert emails from MBOX to EML format
  2. Import EML to Windows Live Mail.
  3. Export emails from Windows Live Mail to Outlook PST.

We will go through each step in a more detailed manner.

Exporting Emails from Thunderbird to EML format

To convert MBOX files to EML format, the first step requires locating the required email messages via the Thunderbird client manually. Once located, follow the given instructions carefully.

  1. Select the messages that are to be exported. You can either select individual messages or press Ctrl + A to select all emails in the desired folder.
  2. Right-click on the selected items and select Save As > EML files.
  3. Select a destination path to save the EML files and click the Save button.

Selected emails will get saved to the specified location with the extension (.eml).

Import EML to Windows Live Mail

The second step involves importing the saved EML files to Live Mail’s mailbox. You can do it manually by following these steps:

  1. Launch Live Mail on your Windows machine. Create a new folder or choose an existing one to move the data.
  2. Launch Windows Explorer and locate the folder containing EML files.
  3. Select the required EML files that are needed to be exported to PST and drag & drop those emails to the desired Live Mail folder.

Export emails from Live Mail to Outlook PST

At last, all you have to do is export the imported data from Live Mail to Outlook PST. In order to do that, follow the given instructions:

  1. Launch Live Mail; go to File > Export emails > Email messages.
  2. In the Live Mail export wizard, select Microsoft Exchange and click Next.
  3. In the Choose Profile dialog box, select Outlook as the profile and click OK.
  4. Now, select the required EML folder that needs to be exported to Outlook and click OK.

Thunderbird to Outlook Migration on Linux

Like Thunderbird, Linux is also an open-source platform with support for multiple email client applications. However, Thunderbird is the most preferred email client for Linux-based users.

Thunderbird stores its data in MBOX format, whether you are using it on Windows, Mac, or Linux. Therefore, to migrate Thunderbird emails (Linux) to Outlook (Windows), first, you have to locate Thunderbird mailbox data on Linux. Usually, Thunderbird emails are saved at the following location on your Linux machine.


Once you get the source location of Thunderbird mailbox data, all you have to do is: Go to the Home directory, press Ctrl + H to unhide hidden files, copy the entire directory and paste it on an external storage device. The data on the external hard drive is then moved to the Windows platform and converted to PST.

Automated Tool for Thunderbird to Outlook PST Migration

Till now, it is quite evident that data migration from Thunderbird to Outlook PST using the manual approach requires a lot of precision and skills. For a novice user, it isn’t very easy to perform the migration without proper guidance. Therefore, to make the migration process easy and quick, one should always look for third-party resources.

Kernel for MBOX to PST Converter tool is the most recommended tool to convert Thunderbird’s MBOX file to Outlook PST. This third-party software converts the data leaving the quality and integrity of data intact.

To convert MBOX files to PST format via this tool, follow these simple steps.

  1. Launch the MBOX Converter tool on your system. Install Thunderbird to PST converter software
  2. Select the mode to add files for the conversion task. To add more than a single MBOX file, select the “Select File(s)” option, whereas to import an entire folder containing MBOX files, choose the “Select Folder” option. Once the mode is selected, click Browse to locate the folder containing MBOX files. Select mode to add files for conversion
  3. Select the required MBOX file and click Open. Then, click on the Finish button. Navigate to the directory containing the Thunderbird MBOX files
  4. The next window contains the preview of the mailbox data associated with the selected MBOX file. You can see the mailbox folders on the left panel. Select an individual item to display its email contents. Once you are done previewing the data, click on the Save button to save the required file. Select MBOX file and open
  5. As soon as you click the Save button, a new window will appear on your screen. Select PST file (MS Outlook) as the output format and click Next. Click finish to complete adding files
  6. In the next window, you can filter the data to save only specific files for your converted PST. Apply the desired filters and click Next. Preview of emails and other mailboxes
  7. To manage huge data files, you can use the Split option provided by the tool. Click on the Split option and choose the size available from the drop-down list. You can also add a prefix to the file name. Both changes are optional, in case you don’t want to make these changes, click Next. Select PST as a saving option
  8. Browse to specify a destination path to save the converted PST and click on the Finish button. Select filter option
  9. Click OK to finish the conversion process. Split large PST files

Wrapping Up

Thunderbird uses a common file format to save its data, whether deployed on a Windows, Mac, or Linux machine, whereas Outlook uses PST on Windows and OLM on Mac. If the MBOX to Outlook migration has to be done only for the Windows environment, then the most recommended way is to use third-party Thunderbird Mail Backup software. This tool can convert MBOX, MBS, and MSF files to Outlook PST, DBX, EML, or MSG from more than 20 clients, including Thunderbird, Apple Mail, Google Takeout, Eudora, ZohoMail, etc. Thus it can be called a one-stop solution to export MBOX to Outlook PST, Office 365, and Gmail.