The mailman queue processor /usr/lib/mailman/bin/qrunner is not running on your system.
I get this issue because Mailman is not started: The mailman queue processor /usr/lib/mailman/bin/qrunner is not running on your system. It can be started in the Bootup and Shutdown module.
para resolver este problema , ingresar al panel :10000 , luego ir a :
System Settings -> Features and Plugins, and in there you can disable the Mailman feature.