This article describes the major changes in Thunderbird version 15. For a complete list of bugs that have been resolved in the release, refer to the complete TB15 bugs fixed list.

Ubuntu One added to FileLink providers

This Thunderbird release adds Ubuntu One support to Filelink to complement the existing Filelink provider, YouSendIt. This will allow sending of large attachments with Ubuntu One in addition to YouSendIt.

You will see Ubuntu One when adding a new outgoing provider for attachments:

• In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings. .
• click on the Attachments tab and then click on the Outgoing sub-tab and then click Add

See the Filelink for Large Attachments article for instructions on how to send large files with UbuntuOne and YouSendIt

Instant Messaging & Chat using Facebook, Twitter, GTalk, IRC and XMPP

Thunderbird 15 now supports chat: you now can enjoy real time conversation with your contacts, right from Thunderbird alongside your email, RSS and NNTP messages. Additionally, Thunderbird makes it easy to search through both past instant messaging conversations and emails.

See the Instant Messaging and Chat article for instructions on how chat and use instant messaging using Thunderbird

Do Not Track

A few months ago we added Search the Web to Thunderbird. Thunderbird 15 implements the Do Not Track option associated with Search the Web.

When this feature is enabled, Thunderbird will tell advertising networks and other websites and applications that you want to opt-out of tracking for purposes like behavioral advertising.

To turn the feature on (by default it's off):

• In the Menu bar at the top of the screen, click Firefox and then select Preferences or Settings, depending on your macOS version.Click the menu button and select Settings. .
• click on the Security tab and then click on the Web Content sub-tab and then check Tell web sites I do not want to be tracked

For further information, please consult the Mozilla Do Not Track FAQ

New Australis Theme

Thunderbird has implemented a brand new menu and toolbar design codenamed Australis. This is to harmonize with similar work in a future version of Firefox. See:

• Thunderbird UX blog Australis posts for insight into the Thunderbird design process
• Firefox Australis Feature Page for insights from the Firefox Design and UX team
• Firefox Australis design mockups for Windows 7, Mac and Linux.