Thunderbird ESR has been discontinued

Support for Thunderbird 24.x ESR has ended and there will no longer be any further Thunderbird ESR releases. Starting with Thunderbird 31.x, Mozilla is basing the mainstream Thunderbird releases off of the Firefox ESR standards, so Thunderbird ESR releases have been merged into the mainstream Thunderbird releases. This means the mainstream releases will be stable for about one year before a major update is released. Click here for more information.