Installing Thunderbird 6.0.2 on Ubuntu 11.04
Installing Thunderbird via Ubuntu Software Centre will install Thunderbird 3. The latest version of Thunderbird available is 6.0.2. This is the way to install the latest Thunderbird.
1. Open up your terminal.
2. Type the following.
sudo add-apt-repository ppa:mozillateam/thunderbird-stable
sudo apt-get update
sudo apt-get install thunderbird
And done!