Spam filter fails on Outlook Express

Several of my web sites have contact forms. Some of them are being used by nut cases to send a message containing rubbish.
Like any other spam, the sender's name is changed each time. However, the rubbish in the body of the message is the same each time.
I used to be able to utilise a constant like that to set a message rule in Outlook Express. I would set the filter to look for one or more of the rubbish words in the body of the email, and then I set the filter to to delete the message from the server.
Now, the message rule fails to delete the email from the server. Has something changed in Outlook Express?

Regards

awestruck