Long live the software patent

If any of you still regarded software patent as something positive, please consider the fact that the anti-virus specialist company McAfee registered a US patent (nr. 6,732,157) that is very likely to lock the market of anti-spam softwares. Here is the description:
"comprehensive anti-spam system, method, and computer program product for filtering unwanted e-mail messages"
They also describe the methods to fight against spam.