[bharath]

There are 2 cases to look at: 1) Personal email IDs: Most people used some form of web-based email. For those of us that use Gmail for example, I dont know if spam is that big of a problem anymore. Some spam (at least for me) makes its way through the gmail filters -- but its at a level where I can live with it. I would imagine that Google's recent Postini acquisition will end up making the Gmail anti-spam solution better. 2) So that leaves us with enterprises. The solutions proposed in the article will not work for enterprises. DKIM for example, will not work in the botnet case. CAPTCHA based solutions have usability constraints -- they cannot be mandated upon customers and others who frequently mail people within the organization. So most enterprises are forced to rely on gateway based antispam solution thats basically a cat and mouse game.