After the furore surrounding Mozilla’s recent announcement that it’s to place its email client, Thunderbird, into an “extended support release”, the launch of Thunderbird 15.0 Beta 1 was always bound to attract attention. And it’s certainly turning heads, thanks to the official debut of a redesigned user interface.

Thunderbird 15 Beta 1 also debuts two noticeable new features in addition to the revamped user interface, extending the global search tool to cover the Chat module, plus implementing the “do not track” feature that debuted in Firefox last year.

The most obvious change in Thunderbird 15 will be the implementation of a new, curvaceous user interface called Australis. This introduces itself immediately with the rounded tabs at the top of the screen, but extends to redesigned lines, a repositioned toolbar and categorized filters, and has the effect of bringing the user interface up to date.

The Australis user interface makes its debut in Thunderbird 15

Revamped user interface aside, there are two notable new features. The unified global search now covers the chat module – which supports Facebook, Twitter and Google Talk among others – while the “Do not track” option introduced in Firefox has been added to Thunderbird too. This option – accessible from the Web Content tab in the Security section of Thunderbird’s Options screen – is of less relevance to email users, but may stop some emails from tracking the user, but only if they’ve signed up for the voluntary code of practice.

Going forward, Mozilla plans to split Thunderbird into two separate code bases, with Thunderbird ESR being maintained by Mozilla and Thunderbird being handed over to the open-source community to develop further. Thunderbird ESR will be updated every six weeks for stability and security only, and its changes rolled into whatever new build of Thunderbird has been developed in that timeframe. It means that while the long-term future of Thunderbird is uncertain, in the short to medium term it remains a viable email client for its 20 million user base.

Thunderbird 15.0 Beta 1, which installs over the top of any existing stable Thunderbird release, is available now as a free, open-source download for Windows, Mac and Linux.