Mozilla’s Thunderbird is a great email program (we use it!) but it doesn’t have any built in backup tools. If something goes wrong, or you want to move your profile to another computer, you’ll need a backup.
Windows 10
First of all, make sure Thunderbird is not running.
Open Windows Explorer. In Folder Options, enable “Show Hidden Files, Folder and Drives” .
Then browse to C:\Users\yourloginname\AppData\Roaming, where you will see a folder named Thunderbird.
The Thunderbird folder contains all your Thunderbird settings and address book, as well as all your emails, so it is this folder that you need to copy to your external drive, desktop, or wherever, as your backup. It’s likely to be a very large amount of data so expect it to take a long time!
When you’re done, don’t forget to disable the hidden files view in Windows Explorer by selecting “Don’t Show Hidden Files, Folder and Drives”.
Linux
Make sure that Thunderbird is not running.
Open File Manager (Thunar). Select “Show Hidden Files” from View in the menu bar (or use keyboard combination Ctrl +H) .
In your Home directory (usually your name) look for a hidden directory named .thunderbird (the preceeding dot is part of the directory name and signifies that the directory is hidden) . This is where all your emails, address book and configuration files are stored. It is this directory that you need to copy to your external drive or wherever you want to store your backup. Expect it to take quite a while – it is likely to be a large amount of data.
When you’re done, don’t forget to disable the hidden files view in your File Manager by deselecting “Show Hidden Files” from View in the menu bar (or use keyboard combination Ctrl +H) .