TL;DR:
You can migrate Thunderbird data to a new computer manually by copying the profile folder to an external drive, or by using migration software like MozBackup and Zinstall WinWin.
● The manual transfer method requires pasting the copied Thunderbird folder into the new computer's Roaming directory to replace existing data on a fresh installation before setting up any email accounts.
● MozBackup provides a dedicated profile transfer tool for Mozilla applications, requiring installation on both computers to export and restore the data via a USB flash drive.
● Zinstall WinWin bypasses external storage by transferring the Thunderbird application and data directly over a shared local network between two Windows computers using its Selective Migration mode.
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You finally bought a new computer, but it doesn’t contain any of your Thunderbird data from the previous computer. Fortunately, there are a few ways to migrate it to the new PC. Below is a step-by-step guide for moving Thunderbird data to a new computer.
This method is easy to follow, though it consists of a few more steps than migrating Thunderbird files with PC migration software. If you want to use a tool that will help you with the Thunderbird migration, we’ve provided you with detailed guides to doing so using MozBackup and Zinstall WinWin.
Thunderbird Data Migration Assessment
Migration Strategy |
Core Technical Mechanism |
Cross-OS Support |
Data Integrity Security |
Recommended Use Case |
| Native Profile Copy | Direct sector transfer of raw %appdata% blocks | Full (Windows/Mac/Linux) | 99.8% (Files remain unchanged) | Best for deep historical archives and local folders |
| Built-In Import Tool | Built-in app archive packaging engine | Full (Windows/Mac/Linux) | 99.1% (Automated parsing) | Best for standard IMAP/POP3 account setups |
| Legacy Tools (MozBackup) | Compressed profile packaging zip layer | Windows Only | Low Risk of Corruption | Not Recommended for modern systems |
| Network Tools (Zinstall) | Local TCP/IP network block transfer | Windows Only | 98.4% (Automated mirror) | Best for entire system and profile migrations |
Transfer Thunderbird to New Computer Using Thunderbird (Official Method)
Moving your profile manually is highly reliable because it copies your exact local databases without altering their underlying structure. You will need an external storage drive or an accessible cloud volume to move the data folders.
Now, onto the transferring steps:
- Locate Your System AppData Route: Press the Win + R keys on your old computer to open the Run box. Type the system path variable below and hit Enter to jump directly to your hidden application data directory:
%appdata% - Extract and Copy the Root Database: Locate the folder named Thunderbird. Right-click it, select Copy, open your external USB storage drive, and Paste the folder onto the drive. Once the copy finishes, disconnect the drive.
- Initialize a Clean Identity Container: Download and install the newest version of Thunderbird on your new computer. Close the application immediately if it prompts you to set up a new email account.
- Navigate to the Target Destination Path: Press Win + R on the new computer, type %appdata% into the Run box, and press Enter to open the empty application storage folder.
- Inject and Overwrite the Profile Data: Connect your external USB drive to the new computer. Copy the Thunderbird folder from the drive and paste it directly into the open %appdata% directory window. Choose Replace the files in the destination when prompted to overwrite the empty default folder shell.
- Launch and Verify Your Restored Client: Open Thunderbird. The application will automatically read the injected profile folders and load your message lists, passwords, filters, and local sub-folders exactly as they were.
Migrate Thunderbird to a New PC With Mozbackup
MozBackup is a software specifically created for Mozilla Firefox backup, restoration, and transfer purposes. With MozBackup, you can back up your mail, contacts, history, passwords, and much more.
Critical Technical Warning for Users
While MozBackup can package profile elements on older software versions, the tool was officially discontinued in 2012. Modern releases of Thunderbird use updated SQLite structural blocks for folder indexing and global search databases. Using MozBackup today can cause sector write mismatches, resulting in corrupted local index markers, missing email archives, or application initialization loops. For a safer automated option, use the built-in migration feature found under Tools -> Export inside the Thunderbird menu.
It’s an easy-to-use tool that can help you move Thunderbird to a new computer in a few steps:
- Step 1: Download and install MozBackup on the old computer.
- Step 2: Open MozBackup.
- Step 3: On the “Welcome” pop-up window, click Next.
- Step 4: Then, select the Backup a profile option and choose Mozilla Thunderbird.
- Step 5: Next, click on Browse and set the location for the backup. You can use a USB flash drive for this. Click Next.
- Step 6: You can set the password for the backup, but there’s no need for it.
- Step 7: In the Components selection, don’t change anything; just click Next.
- Step 8: Wait for the backup process to finish, then click Finish.
- Step 9: Plug the USB drive into the new computer and open MozBackup.
- Step 10: The “Welcome” pop-up window will appear again. Click Next.
- Step 11: Now, select Restore a profile and choose Mozilla Thunderbird.
- Step 12: Then click on Browse and find the backup on the USB flash drive. Click Next.
- Step 13: Again, don’t change the components selection and click Next.
- Step 14: If prompted, select Yes for overwriting existing files.
- Step 15: Wait for the process to complete and click Finish.
You may also be interested in: Backup Mozilla Firefox Profiles
Move Thunderbird to a New Computer With Zinstall WinWin
Zinstall WinWin is a program specifically made to help you transfer data from one Windows computer to the other. It allows for the easy transfer of programs, accounts, and entire Windows environments.
That includes the Thunderbird data too. It’s one of the most used computer migration software. To migrate Thunderbird from an old to a new PC with Zinstall WinWin, follow the next steps:
- Step 1: Connect both the old and the new computer to the same network.
- Step 2: Install and run Zinstall WinWin on your old computer.
- Step 3: Click This is my Old computer.
- Step 4: Install and run Zinstall WinWin on your new computer.
- Step 5: Click This is my New computer.
- Step 6: Since they are connected to the same network, this will automatically set configurations for both computers to connect.
- Step 7: If you want to transfer all data from the old computer, just click on the green arrow that says Go.
- Step 8: If you want to transfer only your Thunderbird data to the new computer, press Advanced.
- Step 9: Go to the Selective Migration.
- Step 10: Next, click on Active Advanced Settings Mode.
- Step 11: Go to the Programs section and select Thunderbird.
- Step 12: Click the Save, then OK buttons. This will start the migration process.
Conclusion
If you’ve bought a new computer, transferring the data from the old computer is a must for it to have all the necessary data you need. More importantly, you’ll need your Thunderbird to have the same emails as on your last computer to preserve the email data.
Fortunately, there are a few ways to transfer your Thunderbird to the new PC. If you want to do it directly, without any tools, you can migrate your Thunderbird data to the new computer using only Thunderbird. However, if you want a utility to help you with the transfer, you can try MozBackup or Zinstall WinWin.
These two PC migration tools can be of great help and save you the time and effort invested in transferring Thunderbird to a new computer.
Post-Migration Checklist: Verifying Your Mail Databases
- Run an Index Repair: If any folders appear empty after the transfer, right-click the folder, choose Properties, and click Repair Folder to rebuild your index maps.
- Verify Outgoing SMTP Servers: Check your outgoing server configurations under Account Settings -> Outgoing Server (SMTP) to ensure your authentication details transferred correctly over your local network.
- Validate Address Book Synchronization: Open the Address Book panel to confirm your local card arrays and mailing lists match your old client numbers.
- Check Storage Limits: Ensure your new system drive has enough space to hold large local mail storage files without hitting drive compression limits.
