Just for my references. I made changes to it before, but I now added the comments to them (for custom notifications and acknowledgements):

define command{
        command_name    notify-host-by-email
        command_line    /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nComment: $NOTIFICATIONCOMMENT$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /usr/bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert ($SHORTDATETIME$): $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTEMAIL$
}
 
define command{
        command_name    notify-service-by-email
        command_line    /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nComment: $NOTIFICATIONCOMMENT$\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$" | /usr/bin/mail -s "** $NOTIFICATIONTYPE$ Service Alert ($SHORTDATETIME$): $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$
}
 
define command{
        command_name    notify-host-by-sms
        command_line    /usr/local/sbin/send-sms.sh -n $CONTACTPAGER$ -m "$HOSTNAME$: $NOTIFICATIONTYPE$, $HOSTSTATE$ ($NOTIFICATIONCOMMENT$)"
}
 
define command{
        command_name    notify-service-by-sms
        command_line    /usr/local/sbin/send-sms.sh -n $CONTACTPAGER$ -m "$SERVICEDESC$ on $HOSTNAME$ $NOTIFICATIONTYPE$ ($NOTIFICATIONCOMMENT$): $SERVICEOUTPUT$"
}