Moving Thunderbird Data to a New Computer
How to move Thunderbird data (accounts, messages, passwords) to a new computer.
Profiles - Where Thunderbird stores your messages and other user data
Thunderbird saves personal information such as messages, passwords and user preferences in a set of files called a "profile".
Export your Thunderbird Profile
Thunderbird's export tool lets you create a backup of your Thunderbird profile including accounts, messages, address books, and settings.
Import settings and data into Thunderbird
With Thunderbird's import tool, you can import settings and data from a variety of sources including Thunderbird profiles, other applications or files.