Is pop3-filter in kmail 1.4 broken?

Is pop3-filter in kmail 1.4 broken or am I doing the wrong thing? I have set up my pop3-filter so that messages where any header contains the string "mail[a-z].telia.com" "hotmail" and "yahoo" should be deleted on the server. They don't, which is most annoying, since I get flooded in spam from these locations. Has anyone else experienced this, and if so - is there a solution?