[WBEL-users] Help with mail.

[Cameron Showalter]

from the server console, you can type iptables -L, which will give you a 
list of ports blocked.  typically with centos unless you disable the 
firewall or open smtp, port 25 is blocked.  to clear it out - until next 
reboot (or you do service iptables restart), type iptable -F

I think there is a system-config-firewall installed, you can run that 
also to customize.   or if you like vim, /etc/sysconfig/iptables is the 
file that controls the default firewall config. 

from another server, you can type nmap [yourserver/ip] and it will list 
what is open.   you will see filtered or closed if port 25 is blocked.

hth,
cameron