Sorry, but this is nothing to do with thunderbird. The error message is coming from an extension you have installed
** Changed in: thunderbird (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/750556 Title: thunderbird-gnome-support depends on libnotify-bin -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs