Procedure

1. Restart the first Sendmail daemon to receive SMTP traffic on port 25 using the following command:
   • RedHat Enterprise Linux 6
     # /etc/init.d/sendmail restart
   • RedHat Enterprise Linux 7 or 8
     #systemctl restart sendmail
2. Create the following new file for the second Sendmail daemon.

   Note Make sure there are no extra trailing spaces in each line of the new file.

   • RedHat Enterprise Linux 6
     Create the sendmail_delivery file.
     vi /etc/init.d/sendmail_delivery

     #!/bin/bash
     #
     # sendmail_delivery  This shell script takes care of 
     #                    starting and stopping
     #                    sendmail_delivery
     #
     # chkconfig: 2345 80 30
     #
     
     PROG=sendmail_delivery
     CONFFILE=/etc/mail/sendmail.cf.delivery
     PIDFILE=/var/run/sendmail_delivery.pid
     
     # Source function library.
     . /etc/rc.d/init.d/functions
     
     # Source networking configuration.
     [ -f /etc/sysconfig/network ] && \
     . /etc/sysconfig/network
     
     # Source sendmail configureation.
     if [ -f /etc/sysconfig/sendmail ]; then
         . /etc/sysconfig/sendmail
     else
         DAEMON=no
         QUEUE=1h
     fi
     
     # Check that we're a privileged user
     [ `id -u` = 0 ] || exit 4
     
     # Check that networking is up.
     [ "${NETWORKING}" = "no" ] && exit 1
     
     [ -x /usr/sbin/sendmail ] || exit 5
     
     start() {
         ret=0
         echo -n $"Starting $PROG: "
         daemon --pidfile $PIDFILE /usr/sbin/sendmail \
             $([ "x$DAEMON" = xyes ] && echo -bd) \
     	$([ -n "$QUEUE" ] && echo -q$QUEUE) \
             $SENDMAIL_OPTARG -C $CONFFILE
         RETVAL=$?
         echo
         [ $RETVAL -eq 0 ] && touch /var/lock/subsys/$PROG
         let ret+=$RETVAL
     
         [ $ret -eq 0 ] && return 0 || return 1
     }
     
     stop() {
         echo -n $"Shutting down $PROG: "
         killproc $PROG
         RETVAL=$?
         echo
         [ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/$PROG
         return $RETVAL
     }
     
     status -p $PIDFILE >/dev/null
     running=$?
     
     case "$1" in
         start)
     	[ $running -eq 0 ] && exit 0
     	start
     	RETVAL=$?
     	;;
         stop)
     	[ $running -eq 0 ] || exit 0
     	stop
     	RETVAL=$?
     	;;
         restart)
     	stop
     	start
     	RETVAL=$?
     	;;
         status)
     	echo -n $PROG ; status -p $PIDFILE -l $PROG
     	RETVAL=$?
     	;;
         *)
     	echo $"Usage: $0 {start|stop|restart|status}"
     	RETVAL=2
     esac
     
     exit $RETVAL
     

   • RedHat Enterprise Linux 7 or 8
     1. Create the sendmail_delivery.service file.
        vi /usr/lib/systemd/system/sendmail_delivery.service

        [Unit]
         Description=Sendmail Mail Transport Agent 
         for Delivery
         After=syslog.target network.target
         Conflicts=postfix.service exim.service
        
         [Service]
         Type=forking
         StartLimitInterval=0
         PIDFile=/var/run/sendmail_delivery.pid
         Environment=SENDMAIL_OPTS="-q1h"
         EnvironmentFile=-/etc/sysconfig/sendmail
         ExecStartPre=-/etc/mail/make
         ExecStartPre=-/etc/mail/make aliases
         ExecStart=/usr/sbin/sendmail -bd $SENDMAIL_OPTS 
         $SENDMAIL_OPTARG -C /etc/mail/sendmail.cf.delivery
        
         [Install]
         WantedBy=multi-user.target

     2. Create a soft link to the sendmail_delivery.service file.
        ln -s /usr/lib/systemd/system/sendmail_delivery.service /etc/systemd/system/multi-user.target.wants/sendmail_delivery
3. Restart the second Sendmail daemon to receive SMTP traffic from IMSS using the following command:
   • RedHat Enterprise Linux 6
     #chmod 755 /etc/init.d/sendmail_delivery
     # /etc/init.d/sendmail_delivery restart
   • RedHat Enterprise Linux 7 or 8
     #systemctl restart sendmail_delivery