Mozilla Thunderbird is a standalone mail and newsgroup client. This erratum blacklists a small number of HTTPS certificates. This update also fixes the following bug: * The RHSA-2011:0312 and RHSA-2011:0311 updates introduced a regression, preventing some Java content and plug-ins written in Java from loading. With this update, the Java content and plug-ins work as expected. All Thunderbird users should upgrade to this updated package, which resolves these issues. All running instances of Thunderbird must be restarted for the update to take effect.