Mozilla has placed the final code for Thunderbird 5.0 on its download servers. Version 5.0 represents the first major upgrade of Thunderbird for 18 months, although the number of headline features is relatively small: an improved email account wizard, better and more versatile tab handling, and a brand new Add-ons Manager and extensions management API.
There's also a new troubleshooting information page (accessible from the Help menu) that contains key information about your individual Thunderbird setup to aid fixing problems that may occur, as well as the fact attachments are now displayed with the file size next to them.
The new, improved email account wizard follows the example of other email programs in simplifying the task of setting up your account: just enter your address and password, and Thunderbird will attempt to detect the settings required automatically for you from its own database.
Tabs can now be reordered and dragged to other open windows, while the brand new Add-ons Manager apes that found in Firefox. Mozilla also claims the software is more responsive as well as being quicker to start and use, in part thanks to nearly 400 platform fixes that improve performance as well as stability and security.
Those wondering what happened to Thunderbird 4.0 will be relieved to learn you've not missed an entire major upgrade; the release number skips version 4.0 in order to synchronize Thunderbird with Firefox (also currently at version 5.0). This also confirms that Mozilla is switching Thunderbird to the same rapid release cycle as Firefox, meaning new version numbers will be appearing every three months or so in the future -- Thunderbird 5.0 itself was only launched as a beta at the beginning of this month.
Thunderbird 5.0 is available now as an open-source, free download for Windows, Mac and Linux.