Mozilla now plays an alert sound when new messages arrive. A new sidebar item for global history has been added. The history and bookmark managers can now remember sort orders between sessions. Drag and drop for mail folders is available. New windows now cascade properly instead of loading on top of each other.
New preferences are available for display of animated gifs.
You can now choose not to animate images or to only cycle through them once. On Linux, popups and context menus can now be used with a single drag. Improved support for system colors on Linux, Windows NT, and Windows 2000 is in place. In mail, you can now sort by unread in the threaded view. On Mac and Windows, when you download a file, you have the option to launch the file when the download completes or to open your file manager to the directory location of the downloaded file.