#!/bin/bash
# As my preferred Exchange add-on doesn't like Thunderbird 15, it has to be downgraded. Here is a guide on how to do it:
sudo add-apt-repository ppa:mozillateam/thunderbird-stable #to make sure access the official repositories
sudo apt-get update # to get the descriptions
sudo apt-cache showpkg thunderbird # to list the available versions
sudo apt-get install thunderbird=14.0+build1-0ubuntu0.11.10.1 # install the desired package, this might remove some packages
sudo apt-get install thunderbird-locale-de=1:14.0+build1-0ubuntu0.11.10.1 \
  thunderbird-locale-da=1:14.0+build1-0ubuntu0.11.10.1 \
  thunderbird-locale-en=1:14.0+build1-0ubuntu0.11.10.1 \
  thunderbird-locale-en-gb=1:14.0+build1-0ubuntu0.11.10.1 # make sure to reinstall the packages you need
# goto https://addons.mozilla.org/en-US/thunderbird/addon/lightning/versions/, get the right version of lightning and you should be done