Thunderbird 3.1.16 has been released. Users on 3.1.15 or older may update via Help > Check for Updates. This release included several fixes to improve stability and security, see the Security Advisory. For a more detailed list of bug fixes, see the complete list of changes in this version. Unless there is a firedrill release prior, the next version (3.1.17) will be released on December 20th, 2011.