seem to be a bit short on support documentation but it would be good to ask the ISP.
From looking around their boards.iol.ie forums it would seem that you need to use the following servers in outlook express:
"Make sure you have set pop.iol.ie as incoming POP server and mail.iol.ie as your outgoing SMTP server."
May or may not need to put in login information also. I would have thought you would.