This is a bugfix release that improves Mozilla's email client
Canonical announced a couple of days ago, December 11, that the recently released Mozilla Thunderbird 24.2.0 email client landed in the Ubuntu 13.10, Ubuntu 13.04, Ubuntu 12.10, and Ubuntu 12.04 LTS operating systems.Officially released by Mozilla on December 10, 2013, the Mozilla Thunderbird 24.2.0 email client is a bugfix release that solves an issue where long email messages that had multiple signatures might no longer be readable, and fixes a problem where users were not able to edit account settings in various non-standard configurations of local folder setups, as well as several security issues.
All Ubuntu 13.10 (Saucy Salamander), Ubuntu 13.04 (Raring Ringtail), Ubuntu 12.10 (Quantal Quetzal), and Ubuntu 12.04 LTS (Precise Pangolin) users can update their Mozilla Thunderbird email client to version 24.2.0 right now, using the pre-installed Update Manager app.
Mozilla Thunderbird 24.2.0 can also be downloaded right now from Softpedia for other Linux users. More details can be found in the official security notice issued by Canonical.