Change path

data/conf/postfix/master.cf

@@ -56,4 +56,4 @@ zeyple    unix  -       n       n       -       -       pipe
   -o mynetworks=127.0.0.0/8
   -o smtpd_authorized_xforward_hosts=127.0.0.0/8
 
-127.0.0.1:10027 inet  n       n       n       -       0      spawn user=nobody argv=/opt/postfix/conf/whitelist_forwardinghosts.sh
+127.0.0.1:10027 inet n n n - 0 spawn user=nobody argv=/usr/local/bin/whitelist_forwardinghosts.sh