How to Migrate Thunderbird to Outlook 2019, 2016, 2013, 2010?

Thunderbird is a cross-platform email client for Windows, Mac, and Linux. The open-source email client stores emails, attachments, and other mail items in MBOX files on the local machine.

If you want to migrate Thunderbird mailbox items to Outlook, you need to convert the Thunderbird MBOX files to Outlook importable PST file format. That's the ideal and most efficient way of migrating Thunderbird MBOX to Outlook without errors and risk of data loss.

However, there are other ways to migrate mail items such as emails, contacts, calendar, notes, etc. from Thunderbird to Outlook on Windows or Mac.

There are three possible methods to migrate or move email and attachments from Mozilla Thunderbird email client to Microsoft Outlook.

Method 1: Move Thunderbird Mail Items to Outlook via Gmail IMAP

You can use your Gmail account to sign in to Thunderbird and move mail items from Thunderbird to Outlook. But first, you need to enable IMAP access in your Gmail account. To do so,

• Sign in to your Gmail account and open 'Settings'
•  Click on 'Forwarding and POP/IMAP'and then click the'Enable IMAP' radio button under'IMAP Access' section



•  Click 'Save Changes'

Step 2: Sign in to Thunderbird using Gmail IMAP Account

• Open your Thunderbird app and click on your Thunderbird email account
• Click 'Email' under 'Set up an account'



• Enter your Gmail username and password. Click 'Continue'



•  Click the IMAP radio button and then click on the 'Done' button

If you experience sign-in errors, follow the troubleshooting guide below on Gmail sign-in error.

Troubleshoot Thunderbird Gmail Sign-In Issue

In case the Gmail login fails and you see a sign-in error in Thunderbird, follow these steps,

Disable 2-Step Authentication in your Google account

• Go to https://myaccount.google.com/security
• Sign in and then click '2-Step Authentication'
• Enter your password again to verify
• Then click 'Turn Off' to disable 2-Step Authentication

Enable 'Less secure app access'

• Go to https://myaccount.google.com/lesssecureapps
• Enable 'Less secure app access' 
• Click on the Allow less secure appstoggle switch to turn ON the option



• Also, visit and follow the setup wizard

Once you are done with these changes, try to sign in to Thunderbird using Gmail credentials. If this still does not work, follow the next method.

Step 3: Copy Thunderbird Mail Items to Gmail Account Folder

• After successful sign in, create a new folder in your configured Gmail account in Thunderbird app
• Right-click on your Gmail Inbox or any folder and choose 'New Subfolder'



• Enter a name and from 'Create as a subfolder of', choose your Gmail Account



• Click Create Folder
• Then copy all your Thunderbird email folders to this new Gmail folder in Thunderbird



• Wait for the Thunderbird to sync the copied emails to Gmail server. This could take a while

• Now open Microsoft Outlook on your Windows or Mac (where you want to migrate Thunderbird mails)and sign in with your Outlook account
• Then sign in with same Gmail account that you used in Thunderbird
• Let Outlook sync all the Gmail folders including the new folder that you created in Thunderbird where you copied all the Thunderbird mails. This may take a while depending on the number of mail items and network speed
• Once synced, copy the folder and paste in your new Outlook account
• After copying the folder, you may sign out from Gmail account. At this stage, you have successfully migrated your Thunderbird to MS Outlook

NOTE: The copied emails are usually inconsistent and may not be in the original format.

Alternatively, instead of copying mail items and folders, you can export the synced Gmail folder that contains Thunderbird mailboxes to PSTfile by using MS Outlook Import/Export wizard.Then import the PST in your Outlook account via Import/Export wizard. Here'show.

• Open Outlook and go to File>Open&Export>Import/Export
• Choose 'Export to a file' and click 'Next'



•  Choose 'Outlook Data File (.pst)' and click 'Next'



• Expand the Gmail profile and choose Folder that contains Thunderbird emails (where you copied the Thunderbird mail)



• Check 'Include subfolders' and click 'Next'
• Then click 'Browse' and select a save location



• Select the desired option and click 'Finish'

You may enter a password or simply click 'OK' to start exporting selected mail items or folder to PST.

Now you can sign out and remove Gmail account from Outlook and import the PST through Import/Export wizard and finish migrating Thunderbird emails to Outlook. The steps are given here.

IMPORTANT NOTES:

• This process will take time as emails are required to be synced at every step
• The folder structure will be lost
• There are chances of missing emails and attachments  

Method 2: Manually Drag 'n' Drop Mail Items to Outlook

This is a time-consuming method but works well when it comes to exporting emails from Thunderbird to Outlook. Follow these steps to manually export emails and address book (contacts) from Thunderbird to MS Outlook on Windows.

• Open File Explorer window on your PC and create a new folder
• Sign in to your Thunderbird
• Hold the Shift key and click on the emails in Thunderbird that you want to migrate to Outlook
• After selecting emails, drag and drop them to the new folder you created
• The emails will be saved with .eml extension

• Open Outlook and sign in to your account
• Create a new folder in the Outlook where you want to import the Thunderbird emails
• Open the folder that contains the .eml files
• Select the.eml files and drag and drop to the Outlook folder that you just created
• Let it finish the import
•  Repeat the steps to import other emails from different Thunderbird email folders

You can also copy these emails or email folders and import the mails on other PC or Mac.

Alternatively, you can open Thunderbird and Outlook side-by-side and drag and drop emails or folders from Thunderbird to Outlook directly. This will quickly migrate Thunderbird mail items to Outlook.

Follow these steps,

• Open 'Thunderbird' and 'Outlook' app on your PC side-by-side
• Create a new folder in Outlook
• Then click on an email item or select multiple emails and then drag them to the Outlook folder

TIP: To select multiple emails at once, click on an email item and press the Shift key. Hold the Shift key and use the arrow down or up key to select multiple email items.

•  Repeat these steps to copy all emails from other folders in Thunderbird to Outlook
• You can also import contacts from Thunderbird to Outlook

IMPORTANT NOTE: You can't estimate how long this process may take to complete. When we tried to import multiple emails at once, the email client freezes. Thus, we had to force close the application and restart again. This could disrupt email properties and folder tree structure when migrating Thunderbird emails to Outlook.

LIMITATIONS AND DRAWBACKS OF MANUAL METHODS

• Not suitable fora large number of emails or batch export from Thunderbird to Outlook
• Chances of data loss and data corruption
• Folder hierarchy is lost and data may be inconsistent
• Can't export deleted emails from Thunderbird to Outlook
• Not to mention, these methods are time-consuming and complex

However, the next method overcomes all these problems.

Method 3: Convert Thunderbird to Outlook by using Stellar Converter for MBOX

As mentioned earlier, the easiest way to migrate Thunderbird to Outlook is to convert the Thunderbird MBOX files to Outlook importable PST. Stellar Converter for MBOX is the best Thunderbird to Outlook converter tool.

By using this Thunderbird to Outlook converter tool, you can move all Thunderbird mail items to MS Outlook while keeping the folder tree structure and data consistency intact.

It also lets you export Thunderbird mailbox items directly to Office 365 account (requires Technician version).

• Close Outlookand Install Stellar Converter for MBOX software on Windows PC
• Copy Thunderbird MBOX files or Identity folders from Mac or Linux system to your Windows PC.
• 1. In Windows,C:\Users\\AppData\Roaming\Thunderbird\Profiles\
  2. In Linux,~/.thunderbird/
  3. In Mac, ~Library/Thunderbird/Profiles/sample. default"
•  If Identity Folder or MBOX files are not found, follow these steps to manually export MBOX files from Thunderbird app:
• 1. Open Thunderbird app and go to 'Tools>Add Ons'
  2. SearchImportExportTools NGand click 'Add to Thunderbird' to install it

  

  3. Then right-click on Thunderbird email profile and select ImportExportTools NG> Exportall the folders

  

  4. Create a new folder and click 'Select Folder'

  

  5. It will save Thunderbird email items in MBOX file format within the folder. This folder can be referred to as Identity Folder

Then follow these steps to convert Thunderbird emails to Outlook PST,

• Launch Stellar Converter for MBOX Software
• Select Thunderbird from 'Email Client' drop-down



• Click 'Select Identity' to browse and select the Identity folder to add Thunderbird MBOX files for conversion



Select the MBOX file(s) from the list and click 'Convert'



• After the conversion, software lists all Thunderbird mail items. At this stage, you can click and preview individual emails and their attachments

NOTE: You must activate the software to export the converted Thunderbird MBOX files to existing Outlook PST or new PST file.

• Make sure Outlook is closed. Click 'Save Converted File' on the top Menu bar under 'Home'tab
• Choose New PST file format and click 'Next'



• Click 'Browse' to choose a save location on your PC or external drive and then click 'Save'

Now you can import this New PST file to your Outlook account via Outlook Import and Export Wizard and migrate Thunderbird to Outlook successfully.

Steps to Import Converted PST File to Outlook Email Profile

You can import this PST to your Outlook on Windows or Mac. You may also import it in Office 365 account.

Import PST in Outlook 2013/2016/2019 for Windows

•  Launch Outlook on your Windows PC and go to File>Open&Export>Import/Export
• Click 'Next'. Choose 'Outlook Data File (.pst)' and click 'Next'



• Click Browse to choose the converted PST file and then click 'Next'



• Select the folder in Outlook profile where you want to import the Thunderbird email items



• Click 'Finish'

Import PST in Outlook 2010

• Navigate to File>Open>Import



• Choose 'Import from another program or file' and click 'Next'



• Select 'Outlook Data File (.pst)' and click 'Next'



• Click on 'Browse'and choose the .PST file. Click 'Next'

  

• Select the email folder to import, select include subfolders' and select the email folder where you want to import emails from PST. Click 'Finish'

Import PST in Outlook for Mac

Open Outlook on your Mac and follow these steps,

• Click 'File>Import….'



• Choose 'Outlook for Windows archive file (.pst)'



• Browse and select the PST file that you exported using Stellar Converter for MBOX software



• Click 'Import' and the Outlook for Mac will start importing the mail items in PST file to your Outlook account

Conclusion

The three methods explained in this guide will help you migrate your mailbox items such as emails, notes, calendar, etc. from Thunderbird to Outlook. You may follow any of these methods based on your requirement and preference.

The two-manual methods explained are efficient if you need to migrate one or two Thunderbird accounts or mailboxes to Outlook that contain only a few hundred emails.

But if the Thunderbird account contains thousands of emails and attachments or you need to migrate multiple Thunderbird accounts to MS Outlook, avoid using these manual methods.

Use a professional MBOX to PST converter tool such as Stellar Converter for MBOX to convert Thunderbird MBOX files to PST. Then import the PST file to your Outlook on Windows or Mac with up to 100% data consistency. The software helps migrate Thunderbird emails to Outlook while maintaining the folder tree structure.  

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About The Author

Ravi Singh

Senior Writer at Stellar®. He is an expert Tech Explainer.