Thunderbird 3 comes with an interesting new interface for arranging your emails which is especially useful if you are using it to handle multiple email accounts. The new "Smart Folders" view automatically bundles special folders from multiple accounts. In the smart folders view, all the Inbox folders from your multiple accounts get bundled together under one global Inbox, containing messages from both accounts. Similarly your Draft, Sent mail and Trash folders are all consolidated. This makes it considerably easier to work with multiple accounts -- a scenario which is becoming more common nowadays.