#!/bin/sh

IP=$(curl ifconfig.me)
curl_retval=$?

if [ $curl_retval -gt 0 ]; then
	# TODO send warning email to postmaster here
	exit 1
fi

host_answer=$(host "$IP")
rev_dns="${host_answer##* }"
rev_dns="${rev_dns%.}"

echo "Rev. DNS is: $rev_dns"

sed -e "s/^myhostname.*/myhostname = $rev_dns/" -i /etc/postfix/main.cf