14 DAY TRIAL // Mozilla has released the next major version of its email client, Thunderbird 5.0, which contains several new features and enhacements, but also a bunch of security and stability fixes.
Thunderbird 5 landed a week after Firefox 5 and is the first Thunderbird release resulting from Mozilla's new rapid development cycle that aims produce a new stable version every six weeks.
The most important change in the new version is that it's based on Gecko 5, the same variant of Mozilla's layout engine used by Firefox 5 and, therefore, contains the same security fixes.
According to the release announcement, Thunderbird 5 includes "over 390 platform fixes that improve speed, performance, stability and security," however, no other details were released.
We can safely assume that the new version contains patches for the vulnerabilities addressed in Thunderbird 3.1.11 which was released last week together with Firefox 3.6.18.
It's not clear how much longer the 3.1 branch will be supported considering that it is already one year old. According to Mozilla's old development cycle, major releases used to be supported for a minimum of six months.
However, the company cut support for Firefox 4 once Firefox 5 came out despite the version being released on March 22 this year. This decision caused quite an uproar among enterprise Firefox adopters.
It's worth noting that Firefox 3.6 is still supported and that Thunderbird skipped over version 4 entirely, going directly from 3.1 to 5.0. It's also not clear if Thunderbird 5 will receive silent updates like Firefox 5, considering that Mozilla hasn't yet sorted out the compatibility issues for Thunderbird extensions.
The latest version of Mozila Thunderbird for Windows can be from here. The latest version of Mozila Thunderbird for Mac can be from here. The latest version of Mozila Thunderbird for Linux can be from here.