For Windows, Mac and Linux: After the huge success, here comes the first security and stability update for Thunderbird 3, Mozilla’s desktop email client. Thunderbird 3.0.1 changelog (complete list of changes) is a list of 125 fixed bugs, 25 of which were critical bugs. Several fixes also regarded the user interface and attachment handling.
Ubuntu users with Thunderbird 3.0 can now check for updates, as they are already available. Simply do Help -> Check for Updates and let it roll-out and install the updates. Then restart Thunderbird. Beware, this new version might put-out-of-use some of your add-ons.