diff --git a/etc/example.conf b/etc/example.conf
index f01393d..8d24b7b 100644
--- a/etc/example.conf
+++ b/etc/example.conf
@@ -52,6 +52,8 @@
 pidfile=/var/run/piler/piler.pid
 
 ; piler will listen here
+; if you have postfix, exim, ... installed on localhost
+; then make sure to set the listen_addr parameter for piler
 listen_addr=0.0.0.0
 listen_port=25