Mozilla Thunderbird 5.0 released

http://www.mozilla.org/en-US/thunderbird/

The latest version of Thunderbird has the following changes:

More responsive and faster to start up and use.
Thunderbird is based on the new Mozilla Gecko 5 engine.
New Add-ons Manager.
Revised account creation wizard to improve email setup.
New Troubleshooting Information page.
Tabs can now be reordered and dragged to different windows.
Attachment sizes now displayed along with attachments.
Plugins can now be loaded in RSS feeds by default.
There are several theme fixes for Windows Vista and Windows 7.
Support for Mac 32/64 bit Universal builds (Thunderbird no longer supports PowerPC on Mac).
Over 390 platform fixes that improve speed, performance, stability and security.