how to tell if pop3 or imap services are running?

[Jay Moore <jay81 pacbell net>]

I've been able to successfully get postfix running.  I can send and 
receive mail to accounts on a RH8 box.  I know this because at a shell 
prompt i use the
'mail' command and can see that mail has been received.  When i've sent 
mail to outside account, it gets there ( i think because the mozilla 
client is configured to use my ISP's SMTP).  However, when i try and use 
a pop3 client (mozilla in this case) to retrieve my mail, i get server 
timeouts etc.  I have a Netgear firewall appliance that has port 110 
open, however, I am unsure if the box itself has this port open.  I'm 
slowly still figuring this stuff out, so any direction at all would be 
helpful.
thanks
jay