go to your address book , the tab controle.
select ignore , enable it. then click the add button.
you will get a pop up tick ctcp in it and for the user add *!*@*
Adding *!*@* is not a good idea just for one person doing it. You'll ignore everyone's ctcps and that can be a problem later on. Just add that person's address. If the person uses different nicks and/or addresses, adjust how you add the nick/address as needed, but avoid *!*@*.