[Postfix] Use name instead of IP

data/Dockerfiles/postfix/whitelist_forwardinghosts.sh

@@ -6,7 +6,7 @@ while read QUERY; do
 		echo "500 dunno"
 		continue
 	fi
-	result=$(curl -s http://172.22.1.251:8081/forwardinghosts.php?host=${QUERY[1]})
+	result=$(curl -s http://nginx:8081/forwardinghosts.php?host=${QUERY[1]})
 	logger -t whitelist_forwardinghosts -p mail.info "Look up ${QUERY[1]} on whitelist, result $result"
 	echo ${result}
 done