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.
Do I need Mailman? We have email accounts on servers, but not using any mailing list manager. So should I follow the instructions and enable it? Or if I dont need it how do I get rid of the issue?