well you could try to run nmap (http://insecure.org
) to se if the port is open
xinetd may not help becasue by default it runs as a daemon.
if you grep your ps output for courier you should find around 6-8 processes (depending on wether or not you are running ssl or not), a bunch are called authdaemond, there should be a couriertcpd and a logger
but first things first, get nmap do a port scan an see what you get (you can use netstat -a is you don;t want to get nmap, but nmap is so handy i would recommend it regardless).