Postfix setup issue

Question

I'm trying to allow an external server to use my webserver (running postfix) to relay email through. I've gone through several articles on setting up iptables and I think I have it, but I still can't get email to flow. I can't do a telnet to port 25 on the webserver either. Below is my iptables. Anyone see anything I missed?

-A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP
-A INPUT -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -m state --state NEW -j DROP
-A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG FIN,SYN,RST,PSH,ACK,URG -j DROP
-A INPUT -i lo -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 25 -j ACCEPT
-A INPUT -p udp -m udp --dport 123 -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -s X.X.X.X/32 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -s X.X.X.X/32 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -i eth0 -p tcp -m tcp --dport 21 -m state --state NEW,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --sport 20 -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -p icmp -j ACCEPT
-A FORWARD -i lo -j ACCEPT
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
-A OUTPUT -p udp -m udp --sport 123 -j ACCEPT
-A OUTPUT -o eth0 -p tcp -m tcp --sport 25 -m state --state NEW,ESTABLISHED -j ACCEPT
-A OUTPUT -o eth0 -p tcp -m tcp --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT

Answer 1

By default postfix is set to listen on 127.0.0.1 in most distro's

1. open /etc/postfix/main.cf
2. Look for a group of lines that start with inet_interfaces

You might see the one uncommented like

inet_interfaces = localhost

That means its only listening on localhost or 127.0.0.1. Change it to

inet_interfaces = all

Then restart postfix and it should work.