Outlook 98

Menu Bar

Actions-Create Rule (left click)

Check the "from" box

Enter next

Check the "delete" box

and hit "Finish"

You will have to manually delete the message you just flagged, but all future messages from that e-mail address will be deleted.

Unfortunately spammers are smarter than Outlook. Xl0.com is one of dumber ones, they only change the address every week, so you get rid of a week's worth and have to do it again. Some use a different one for each mailing.