File permissions.secure of Package nullmailer
# Everyone can queue mail, but only trusted users can view the queue. /usr/bin/mailq mail:trusted 4710 /usr/sbin/nullmailer-queue mail:mail 4711
# Everyone can queue mail, but only trusted users can view the queue. /usr/bin/mailq mail:trusted 4710 /usr/sbin/nullmailer-queue mail:mail 4711