update thunderbird

Can you give the output of:

lsb_release -a; uname -a

What version do you want to upgrade to?

owner@owner-desktop:~$ lsb_release -a; uname -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04.4 LTS
Release: 10.04
Codename: lucid
Linux owner-desktop 2.6.32-40-generic #87-Ubuntu SMP Mon Mar 5 20:26:31 UTC 2012 i686 GNU/Linux

I install lsb here is what I get.
owner@owner-desktop:~$ lsb_release -a; uname -a
LSB Version: core-2.0-ia32:core-2.0-noarch:core-3.0-ia32:core-3.0-noarch:core-3.1-ia32:core-3.1-noarch:core-3.2-ia32:core-3.2-noarch:core-4.0-ia32:core-4.0-noarch:cxx-3.0-ia32:cxx-3.0-noarch:cxx-3.1-ia32:cxx-3.1-noarch:cxx-3.2-ia32:cxx-3.2-noarch:cxx-4.0-ia32:cxx-4.0-noarch:desktop-3.1-ia32:desktop-3.1-noarch:desktop-3.2-ia32:desktop-3.2-noarch:desktop-4.0-ia32:desktop-4.0-noarch:graphics-2.0-ia32:graphics-2.0-noarch:graphics-3.0-ia32:graphics-3.0-noarch:graphics-3.1-ia32:graphics-3.1-noarch:graphics-3.2-ia32:graphics-3.2-noarch:graphics-4.0-ia32:graphics-4.0-noarch:printing-3.2-ia32:printing-3.2-noarch:printing-4.0-ia32:printing-4.0-noarch:qt4-3.1-ia32:qt4-3.1-noarch
Distributor ID: Ubuntu
Description: Ubuntu 10.04.4 LTS
Release: 10.04
Codename: lucid
Linux owner-desktop 2.6.32-40-generic #87-Ubuntu SMP Mon Mar 5 20:26:31 UTC 2012 i686 GNU/Linux

What version do you want to upgrade to?

This version of Thunderbird will be obsolete from April 24th, 2012. You will no longer have the benefit of security and stability enhancements, therefore you will be at greater risk of security vulnerabilities and attack. We strongly recommend that you get the newest version now.

You will not only enjoy a safer and faster email experience but also discover all the great features of the most up-to-date Thunderbird.

    * ThunderbirdFree Download11.0.1 for Linux i686, English (US)

Release Notes - Other Systems & Languages

Can you give /etc/apt/source.list

owner@owner-desktop:~$ /etc/apt/source.list
bash: /etc/apt/source.list: No such file or directory

Thanks actionparsnip, that solved my question.

You are a wizzard action

No, I just used the internet and searched. Anyone can do it..

it seems wrong that we would have to use a 3rd party PPA to keep thunderbird updated. shouldn't thunderbird be updated through the main/default sources that are included with ubuntu?

You could report a bug stating why it should be upgraded in the main repo.

In fact this bug already exist, see: Bug #972840: Thunderbird 11 stable release migration

It seems that Ubuntu 10.04 will be updated with the latest release of Thunderbird.