Mozilla documents how to move Thunderbird data to a new computer by copying the profile folder. Open Troubleshooting Information, find the Profile Folder and copy the hidden .thunderbird folder to a transfer device. Paste it on the new computer and replace the existing data. Both installations need the same or a compatible Thunderbird version. Mozilla warns you not to reopen Thunderbird on the old computer afterward.
Your old mail, folders and settings must reach the new computer. Thunderbird stores all of them in one profile folder. Mozilla describes a copy of that folder as the transfer method.
Facts follow the Mozilla Support article Move Thunderbird data to a new computer. Mozilla lists Thunderbird versions 149 to 160 and 153 ESR. Mozilla last updated it on October 5, 2025.
What to Check Before You Start?
- Version. Update both installations to matching or compatible Thunderbird versions. Mismatched versions can make the transfer fail.
- Backup. Save a copy of the existing data before you replace anything at the destination.
- Old computer. Do not reopen Thunderbird there after the move unless you copy the data back first. Both copies can diverge and Mozilla calls reconciling them by hand tedious.
How to Transfer With a Storage Device?
These steps work on Windows, Linux and Mac. Start on the source machine.
- Connect a USB stick or another storage device.
- Open the Thunderbird menu, select Help and then Troubleshooting Information.
- Find the Profile Folder entry and open it. Button labels differ by operating system.
- Quit Thunderbird.
- Go up the folder tree to the parent folder that contains the hidden .thunderbird folder. Levels to climb depend on your platform.
- Place the .thunderbird folder on the storage device and eject it safely.
Continue on the destination machine.
- Connect the storage device and copy the .thunderbird folder from it.
- Open Thunderbird and close the account setup window if it appears.
- Open Troubleshooting Information again and open the Profile Folder. Then quit Thunderbird.
- Go up to the same parent folder as before.
- Paste the copied folder there and choose to replace the existing data.
What is Different on a Mac?
Press the Option key while you open the Go menu to reveal the Library folder. Copy the Thunderbird folder inside it, for example with AirDrop. Install Thunderbird on the destination Mac and do not open it for mail. Replace its empty Thunderbird folder in Library with yours and test the installation.
How to Move Data Manually on Windows 10 and 11?
- Close Thunderbird on both computers.
- Copy the Thunderbird folder from AppData Roaming of the source PC to transfer media.
- Back up or remove the Thunderbird folder in AppData Roaming of the destination PC.
- Copy the transferred folder into that location and restart Thunderbird.
Different user names on the two machines do not affect this method. If you store your profile at a remote location through Profile Manager, create a new profile at the destination and point it at the same location.
What does Mozilla Not Say?
- Separate Linux steps. Linux appears as an option and no extra steps follow.
- Transfers through a Mozilla account or sync.
- Steps for Thunderbird on Android or for moving from other email clients.
- Recovery when both installations were opened separately.
Related reading: whether Thunderbird opens PST files and how to reindex Thunderbird folders.
Frequently Asked Questions
How do I Move Thunderbird to a New PC?
Copy the hidden .thunderbird profile folder from the source machine to the destination and replace the existing data. Mozilla describes the steps for Windows, Mac and Linux.
Where is the Thunderbird Profile Folder?
Open Help and then Troubleshooting Information in Thunderbird. Select the button next to Profile Folder to open it.
Do Both Computers Need the Same Version?
Yes. Mozilla advises matching or compatible Thunderbird versions on both machines. Mismatched versions can make the transfer fail.
Can I Open Thunderbird on the Old PC Afterward?
Not without copying the data back first. Mozilla warns that both copies can diverge.
Does Mozilla Describe Linux Steps?
No. Linux appears as a selectable option and the article gives no separate instructions.
Key Takeaways
- Thunderbird stores mail and settings in one profile folder.
- Copying the hidden .thunderbird folder moves data on Windows, Mac and Linux.
- Matching or compatible Thunderbird versions are required.
- Mozilla advises a backup before you replace data at the destination.
- Do not reopen Thunderbird on the source machine unless you copy the data back first.
Sources and References
Facts follow Mozilla Support.
- Move Thunderbird data to a new computer (Mozilla Support) support.mozilla.org