This article describes the major changes in Thunderbird version 9. For a complete list of bugs that have been resolved in the release, refer to the Thunderbird Builds thread on MozillaZine. (This article is based on a late beta version of Thunderbird 9.)
There are several cosmetic bugs fixes and improvements in the user interface, including a bug with moving indentation levels to the left in nested lists, displaying quotas in the status bar on Windows, and others.
The compose, message and address book windows now support Personas.
When importing address book entries from Outlook and Outlook Express, the birthday field is now included.
Thunderbird can now handle vCard files. When you open a vCard (for example from your desktop or a web page), Thunderbird will ask if you want to add it to your address book.
Keyboard shortcut changes
When composing a message, the Tab and Ctrl + Tab keys now move through the attachment fields.
There is a new Mac keyboard shortcut for Get Messages / Get All New Messages: Command + Y / Command + Shift + Y. (F5 still works.)
Windows users can toggle the display of the menu bar with the Alt key.