Jul 21, 2011 13:22 GMT  ·  By

Mozilla's Thunderbird team is slowly catching up to the Firefox team and is beginning to adopt the same six weeks release schedule. It already adopted the version scheme, Thunderbird 5 came after Thunderbird 3.1, and the Thunderbird 6 Beta is now available.

"Thunderbird Beta, available now for download, is built on top of the Gecko platform," Mozilla announced.

"While this milestone is considered to be stable, it is intended for developers and members of our testing community to use for evaluation and feedback," it explained.

"Users of this latest beta version of Thunderbird should not expect all of their add-ons to work properly with this milestone," Mozilla cautioned.

Thunderbird 5 has only been released, so the changes aren't that big. Thunderbird 6 uses the Gecko 6 layout engine from Firefox 6, of course, but it also comes with a few new features and changes:

- Support for Windows 7 Jump lists - Several fixes when importing email from Microsoft Outlook - Default mail client check now works with newer Linux distributions - Various other user interface fixes and improvements and numerous other bug fixes.

Thunderbird 5 landed at the end of last month, not long after Firefox 5. As such, Thunderbird 6 should be coming not long after Firefox 6, which is scheduled for a mid-August release.

Mozilla hasn't provided an official date though, so this may not happen if things don't go smoothly.

The Mozilla Messaging team is trying to adapt to the new rapid release schedule. While the Firefox team has done it without a hitch, things need to settle with Thunderbird.

Still, there are already builds of Thunderbird 7 'Earlybird' and of Thunderbird 8 'daily.' As it stands, these will be upgraded as soon as Thunderbird 6 final lands, Earlybird will migrate to the beta channel and the daily Thunderbird 8 builds will move to the Aurora channel equivalent, Earlybird.

Mozilla Thunderbird 6 Beta for Windows is available for download here. Mozilla Thunderbird 6 Beta for Mac OS X is available for download here. Mozilla Thunderbird 6 Beta for Linux is available for download here.