Stability and bug fixes marked yesterday's debut of Thunderbird 5, which like its better-known relation Firefox has adopted a rapid-release cycle. Version-number hawks will notice that Thunderbird 5, available to download for Windows, Mac, and Linux, has skipped version 4 entirely so it can keep pace with Firefox. The new Thunderbird also follows some of Firefox's feature leads by incorporating version 5 of the Mozilla Gecko engine, supporting dragging to reorder tabs, and adding the in-tab add-on manager that launched in Firefox 4 back in March.

A view of Thunderbird Conversations.
A view of Thunderbird Conversations. (Credit: Mozilla)

By and large, the Thunderbird 5 release is more about keeping pace than forging ahead. The highlights of the release are not ground-breaking. The program will launch faster, Mozilla said in a blog post, and the company has also streamlined the account creation wizard for faster e-mail setup. File size will now be included next to e-mail attachment icons, and plug-ins support RSS feeds by default.

Two platform changes include theme fixes for Windows 7 and Vista, while Thunderbird 5 has dropped support for PowerPC on Macs. This follows the end of PowerPC support in version 4 of Firefox.

Also of note are significant improvements to the Thunderbird Conversations add-on. This extension, originally known as Gmail Conversation View, gives Thunderbird a Gmail feel, with e-mail organized along subject threads instead of solely by time stamp. Conversations makes it easy for those who are queasy about using Google's Web-based e-mail service to still get its unique management system.

Read the full changelog for Thunderbird 5 here.