Thunderbird Firefox 15 with new User Interface for download

Mozilla have moved to the Firefox 15 with new features and improvement over the precedent release such as the support for the Ubuntu One OS and Multi-Channel Chat capability, check bellow for the release note.

New

Multi-Channel Chat: You now can enjoy real time conversation with your contacts, right from your favorite messaging application.

Do Not Track: This option has been implemented as an addition to Search the Web.

Ubuntu One is now supported in Filelink - the option to upload large attachments to online storage services.

New User Interface: Thunderbird is replicating the new look and feel of Mozilla Firefox in an effort to provide a similar user experience across all Mozilla software desktop or mobile and all platforms.

Fixed

Various fixes and performance improvements

Various security fixes

Known Issues

If you are unable to view content for your RSS feeds in the Wide View Layout, you can switch to Classic View, or you may need to disable the Lightning Calendar add-on. In both cases, you'll need to restart Thunderbird (see 531397)..