'''On your old computer''' # Press the window key +R # Type %appdata% and press enter (Windows file manger will open showing a list of folders.) # right click the Thunderbird folder and select properties # Note the size of the data to be transferred, because you are going to need a usb drive larger than the size reported. # Right click again and select copy. # open the file manager in a usb drive large enough to hold the profile. Select paste from the menu. '''On your new device''' after you plug in the usb drive # Open the file manager and navigate to the location where the copied Thunderbird folder is located. Drive letters are allocated dynamically so what it will be is anyone's guess. Windows will probably prompt you to open the file manager / explorer when you plug the drive in. # Right click and select copy # press the window key +R # Type %appdata% and press enter (Windows file manger will open showing a list of folders.) # Right click over the list of folder and select paste from the menu. Now install Thunderbird and allow it to run when the install is complete. It should just launch with the old data ready.