Thunderbird has gone alpha, boys and girls, with quite a few major new features and updates, including:

• Message Tags
  
• Folder Views including favorite folders
  
• Improved New Mail Notification Alerts
  
• New Windows installer based on Nullsoft Scriptable Install System
  
• Find As You Type in the message pane
  
• New combined and improved Add-ons manager for extensions and themes
  
• Updates to the extension system to provide enhanced security and to allow for easier localization of extensions

If you're familiar with the term 'alpha' then you probably know your way around playing around with this latest build. However, Mozilla does have one specific warning for Mac OS X users (they even wrote it in bold in the release notes!): do not run it from the disk image. Apparently doing so will lock Thunderbird into an infinite restart loop which you'll need a Terminal command to stop.

With that out of the way, go get your hands on the first major update to Mozilla's flagship email client.