How to Install/Update Thunderbird 15 in Ubuntu 12.04/11.10

How to Install Thunderbird 15 in Ubuntu 12.04/11.10
Mozilla Thunderbirdis a free, open source, cross-platform email and news client developed by the Mozilla Foundation.

Features of Thunderbird

Message management
Junk filtering
Extensions and themes
Standards support
Cross-platform support
Security

To install Mozilla Thunderbird 15 in Ubuntu open terminal (Alt + Ctrl + t) and type following