diff --git a/script/install/ubuntu1604.sh b/script/install/ubuntu1604.sh
index 715df84..9415264 100644
--- a/script/install/ubuntu1604.sh
+++ b/script/install/ubuntu1604.sh
@@ -67,6 +67,13 @@ mkdir /etc/nginx/ssl/
 openssl req -x509 -newkey rsa:4096 -keyout /etc/nginx/ssl/postal.key -out /etc/nginx/ssl/postal.crt -days 365 -nodes -subj "/C=GB/ST=Example/L=Example/O=Example/CN=example.com"
 service nginx reload
 
+#
+# Configure SMTP on port 25
+#
+iptables -t nat -A PREROUTING -p tcp --dport 25 -j REDIRECT --to-port 2525
+iptables -t nat -A OUTPUT -o lo -p tcp --dport 25 -j REDIRECT --to-port 2525
+iptables -I INPUT -p tcp -m tcp --dport 2525 -j ACCEPT
+
 #
 # All done
 #