Migrate Thunderbird Emails, Contacts & Calendar to Outlook

Although Mozilla Thunderbird is an open-source desktop email client widely used for its simple interface and customization (through add-ons), yet users tend to migrate to Microsoft Outlook for its security, phishing detection, and advanced filters, and its integration with the Microsoft Office Suite.

All procedures are listed here to import Thunderbird emails in Outlook 2021, 2019, 2016, 2013, and 2013 with attachments, contacts & calendar.

Important Note: Backup your Thunderbird profile before starting the migration process.

Start Thunderbird to Outlook Transfer Using Tool – Steps

Even with the Thunderbird to Outlook migration tool, you cannot directly import Thunderbird data into the Outlook desktop application (although possible with Outlook.com) due to security. Thunderbird data is converted into PST/OLM format using the tool, which is then imported into your Outlook email client (New, Classic, or Mac).

1. Download and run the solution on your machine.
   
2. Click on convert configured Thunderbird mailbox data. If configured, otherwise select files.
   
3. After pressing the next button, select Thunderbird mailbox data as you need to convert.
   
4. Now, choose the required saving option.
   
5. Browse Filter options and click on Convert to start migrating Thunderbird emails to Outlook.

Steps to Import PST (Converted from Thunderbird) to Outlook

1. Open Outlook and then click on the File option as it appears in the upper menu.
2. Now, choose Open and Export, and next, click on Import/Export.
3. Select Import from another program or file.
4. Click on Next to confirm.
5. Choose the Outlook PST file and click Next to continue.
6. Browse the PST file location that you have converted using the solution.
7. Click on the Finish button to complete the Thunderbird to Outlook migration.

Prime Features of Thunderbird to Outlook Migration Tool

Using the tool is the expert-recommended way to migrate Thunderbird to Outlook. Its advanced yet user-friendly features that streamline and make it easy:

• Migrate any number of Thunderbird profiles (configured or backed up) in one shot without any limitations.
• Import Thunderbird emails, contacts, calendars, at once with hierarchy, attachments, metadata, and other properties fully preserved, ensuring zero data loss.
• It also offers filter options to convert mailbox data as per date range, subject, sender, recipients, exclude folders, root folder, sender blank address, receiver blank address, etc.
• This application is created with a simple interface to be easily operated by any users who may be technical experts or have limited technical knowledge.
• Using the tool is the most secure way to convert Thunderbird to Outlook, as it works offline and complies with international data privacy policies.

Free Manual Way to Migrate Thunderbird Mail into Outlook  (Using IMAP)

To convert Thunderbird emails to use in Outlook, you can use any  IMAP-supported email account, such as Gmail, Yahoo, or Outlook.com, as an intermediate email service to transfer data between the two email accounts.

Here, we use an Outlook.com email account as an intermediate step, which can be directly accessed in Outlook Web.

Part 1: Configure Outlook Account in Thunderbird

1. Open Thunderbird.
2. Click on the Navigation menu on the top-right.
3. Click on Add Mail Account and enter your full name and email address.
4. After pressing continue, it will auto-detect IMAP configuration details.
5. Choose IMAP and click on Done.
6. Log in to the Outlook Account in Thunderbird using OAuth 2.0.

Part 2: Move Thunderbird Emails to Outlook Account

1. Once the account is configured, create a new folder called ThunderbirdImport under the account.
2. Move Thunderbird Custom Mailboxes to Outlook: 
   1. Right-click on the folder >> Move To.
   2. Move then to the newly created ThunderbirdImport folder.
3. For pre-built mailboxes (bulk transfer not possible):
   1. Open the Mailbox (Inbox, Draft, Sent, etc.)
   2. Select emails you want to migrate from Thunderbird to Outlook.
   3. Right-click and choose Move To.
   4. Select the newly created folder.
   5. Alternatively, you can drag and drop the emails into the folder.

Wait for the IMAP sync to get completed. You can verify the completion on the activity bar below before proceeding with further steps.

Part 3: Migrate Thunderbird Contacts (Address Books) to Outlook

1. Open the Address Book in Thunderbird.
2. Locate the account-specific address book of your email.
3. Go to All Address Books.
4. Then, select the contacts you want to move.
5. Drag and drop them into the Outlook account’s remote address book.

Part 4: Add Email Account in Outlook to Complete Migration

1. Open Microsoft Outlook and click on the File.
2. Now, press on Add Account.
3. Enter your email address, and press Continue.
4. Log in to your account in Outlook via Microsoft OAuth 2.0.

You have successfully migrated Thunderbird to Outlook- with contacts & emails.

How to Import Thunderbird Calendar to Outlook? Using ICS Export

IMAP sync does not move Thunderbird calendar data to Outlook. To ensure a complete transfer, you need to export the calendars as ICS files and then import them into Outlook.

1. Open Thunderbird on your PC.
2. Press Alt + 3 to go to Calendars.
3. At the bottom, go to Home.
4. Right-click and choose Export Calendar.
5. Save the ICS file at your desired location on your PC.
6. Open Microsoft Outlook.
7. Click on File.
8. Choose the Open & Export, then select Open Calendar.
9. Open the Thunderbird-exported ICS file to complete the Thunderbird to Outlook migration.

Limitations of the Manual Migration Approach

• This process will take many hours, depending on the size of the mailbox data. Be patient, as all emails will sync between Thunderbird, Gmail, and Outlook.
• Integrity may not be preserved the same as in Thunderbird, and there is no guarantee of getting the entire mailbox data without losing any information.
• Multiple configurations increase the possibility of data loss and file corruption.
• Stable connectivity is required to perform the entire migration.

User Benefits of Migrating Thunderbird to Outlook

• Advanced email management with spam filters.
• Cloud data security.
• Outlook is more reliable- No crashes like Thunderbird.
• Integration with other Microsoft Office Suite applications like Word, Excel, SharePoint, etc.
• Easily manage bulk-sized mailbox data for enterprise and business users.

Common Questions Related to Thunderbird to Outlook Migration

Q1: How do I import only email addresses from Thunderbird to Outlook?
Export email addresses from Thunderbird as CSV. Then, open Outlook >> File >> Open & Export >> Import/Export. Then click on Select Import Program or File and then choose Comma Separated Value (CSV); then press Next to select the exported CSV file from Thunderbird and press Start Import.

Q2: What File Format Does Thunderbird Use to Store Emails?
Thunderbird stores its emails in the MBOX file format. In order to import emails from Thunderbird into Outlook, you need a PST file generated by Thunderbird to Outlook converter.

Q3: What is the free way to export Thunderbird emails to Outlook?

You can migrate Thunderbird to Outlook using the IMAP bridge, or use the ImportExportNG Tools to bulk export Thunderbird emails in EML files, and then open the exported EML files in Outlook. If you have a limited number of emails, you can also use demo version of Thunderbird to Outlook converter.

Final Analysis

In this guide, we have outlined all the information with a reliable solution to migrate Thunderbird to Outlook manually, and using Thunderbird to Outlook Converter. 

The manual approach comes with lots of limitations and a very lengthy process. Hence, we recommend you opt for the expert first choice, Thunderbird to Outlook Migration Tool, as it is specially created for instant output with preserved structure and attributes.