We had numerous "Administrative Prohibition" errors with some system email originating at one cPanel server sent to a second cPanel server. After adding 'Mailer-Daemon: root' to /etc/aliases on both servers, the problem seems fix now.

I am not sure about this -- was adding Mailer-Deamon to /etc/aliases doing the correct or was it a bad work-around for a deeper routed problem? You comments are appreciated.

cPanel.net Support Ticket Number: