Mozilla unleashed a few days ago the first Beta release of the upcoming Thunderbird 10.0 email client for all supported platforms.
Thunderbird 10.0 will include nice features, such as the ability to search the Web, better email searching, drafting email fixes, and the ability to create a new email account, in association with AOL, Hover.com and Yandex.
Thunderbird 10.0 Beta is already available to Ubuntu users. Just add the official Mozilla Thunderbird repository (sudo add-apt-repository ppa:mozillateam/thunderbird-next) and update your machines (sudo apt-get update && sudo apt-get dist-upgrade).
Other Linux users can download the Mozilla Thunderbird 10.0 Beta 1 binaries and source packages for 32-bit and 64-bit architectures right now from Softpedia. However, remember that this is a development release and it should not be installed on production machines.
Also, don't forget to visit our always up-to-date Thunderbird Extensions section, for the latest add-ons!