How to Transfer Emails and Contacts from Thunderbird to Outlook

There are different ways to transfer email messages, contacts, and calendars from Thunderbird to Outlook. While the migration of contacts and calendars is easily achievable through manual means, same cannot be said for moving email messages. It gives user some hiccups here and there due to data loss issues. But that can be handled as well. So here in this blog, we will introduce to you the profound ways to transfer both the emails messages and contacts from Mozilla Thunderbird to Outlook.

Topics covered in the blog:

Without further ado, let us start with the first process.

thunderbird to outlook

Transfer Address Book from Thunderbird to Outlook

Migration of contacts can be done manually using the built in features of both Thunderbird & Outlook. The process is as follows:

  • Launch Mozilla Thunderbird and click on the Address book icon (or hit Ctrl+Shift+B).

  • In the address book window, select All Address Books to transfer all the contact list.

  • Go to Tools and click on Export option.

  • Now select the name and location to save the first address book and click on Save button.

  • It will save the files in .csv file format.

thunderbird contacts

Once you click on the Save button, the window for next Address book will appear. So save all the address books in this manner into CSV format. Once done, follow the steps given below to import the csv contacts in Outlook.

  1. Run MS Outlook and go to File menu.

  2. Select Open & Export and click Import/Export option.

  3. Select the Import from another program or file option in the Import and Export Wizard window that appears, then click Next.

  4. Select Comma Separated Values option in the Import a file window, then select Next.

  5. Click Browse and select the CSV file exported from Thunderbird, then click Next.

  6. Select the folder in Outlook to store the Thunderbird contacts (preferably Contacts folder) and click Next.

  7. Outlook automatically maps the fields in the CSV file with the Outlook address book fields, but you can change the mapping with Map Custom fields button.

  8. Click Finish to complete the process.

This is how you can transfer contacts from Thunderbird to Outlook. There is no requirement of any external guidance or software for this task. Now to transfer emails, let us move onto the next section.

How to Migrate Emails from Thunderbird to Outlook

thunderbird emails

Manual migration of Thunderbird emails to Outlook is fairly easy if you have a certain level of technical knowledge. The process for transferring Thunderbird mailbox to Outlook for free is as follows:

  1. Run Mozilla Thunderbird and open the mailbox folder that contains the email messages you want to transfer.

  2. Select all the email messages manually or simply press Ctrl+A for automatic selection.

  3. Now, right-click on the selected messages and select the Save As option.

  4. Locate a folder to store these email messages and click on Select Folder option.

  5. Quit Thunderbird.

The emails are now saved as EML files in the selected folder. Proceed with the migration in Outlook as follows:

  1. Launch MS Outlook.

  2. Create a new folder and name it accordingly.

  3. Open this empty new folder.

  4. Now, keep Outlook open and select the EML files exported earlier from Thunderbird.

  5. Drag and drop these email messages onto the center pane of Outlook.

  6. Wait for the import process to complete.

This is how you can transfer emails from Thunderbird to Outlook with the manual method.

Important Points to Note:

While the manual method seems capable of getting the job done, it can be deceitful in terms of email migration. There have been multiple issues with the manual method in the past that you need to be aware of as well.

  • Losing Email Attributes: A growing concern among users who have tried manual method is the loss of some of the metadata in email messages. It can be much more impactful when transferring email messages in thousands.
  • Time-consumption: This may not appear to be a major concern at first sight but time-consumption plays a very important role in mail migration. The more the number of emails, the more time it takes for the process to complete. It may eventually lead to hanging issues which can corrupt certain emails. Also the fact that the emails first need to be exported and imported adds to the overall complexity and time consumption as well.
  • Data Loss: During the transfer of emails and contacts from Thunderbird to Outlook, the major concern of a user is loss of data. Human error makes up for 70% of mishappenings with manual data transfer. And the process which requires technical skills and plenty of time to execute, the chances of data loss increases significantly.

So what to do?

To ensure that nothing goes wrong while transferring Thunderbird contacts and emails to Outlook, the best set of process is:

  1. Transfer contacts from Thunderbird to Outlook with manual method (no data loss issue),

  2. Convert Thunderbird Emails to PST and Import in Outlook with SysTools MBOX Converter (no data loss issue).

SysTools MBOX Converter

With this software, migration of Thunderbird emails becomes a child’s play. You can easily extract Thunderbird MBOX files (database files that contain email messages) and convert them to PST format. Thus enabling you to import MBOX to Outlook without any issues. This process ensures that no data is left behind or skipped while transferring Thunderbird emails to Outlook. The method is fast, reliable and user-friendly. More information is in the following inforgraphic:



This article demonstrates how to transfer emails and contacts from Thunderbird to Outlook in a fast and secure way. While the manual method for transferring contacts is perfectly capable to getting the job done, migration of emails is a little tricky. To avoid losing a single bit of email data, it is recommended to go for MBOX converter and import Thunderbird messages in Outlook easily.