* Message Tags: Create your own tags for organizing email. Messages can be
assigned any number of tags. Tags can be combined with saved searches and
mail views to make it easier to organize email.
* Visual Theme:Thunderbird 2's theme and user interface have been updated to
improve usability.
* Session History Navigation: Back and Forward buttons allow navigation through
message history.
* Folder Views: Customize the folder pane to show favorite, unread or recent
folders.
* Improved Support For Extensions: Extensions can now add custom columns to the
message list pane in addition to storing custom message data in the mail
database.
* Improved Offline Management: Thunderbird (Linux and Windows) automatically
adjusts the offline state based on current network connectivity.
* Improved New Mail Notification Alerts:New mail alerts include information
such as the subject, sender and message text.
* Folder Summary Popups: Mouse over a folder with new messages to see a summary
of the new messages in that folder.
* Saved Search Folder Performance: Search results for saved search folders are
now cached, improving folder loading performance.
* Find As You Type
* Improved Filing Tools: Recent folder menu items for moving and copying
folders to recently used folders. Move / Copy again functionality.
* Updates to the extension system: The extension system has been updated to
provide enhanced security and to allow for easier localization of extensions.
Rumbling Edge has a more detailed list of notable bug fixes:
http://weblogs.mozillazine.org/rumblingedge/archives/2006/09/2-0beta1.html
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