If your junk mail folder seems smaller as of late, there's good reason for that. Computer security experts collaborated to take down Grum, the world's third largest botnet, which they say was serving up 18 percent of spam around the globe by way of 18 billion spam messages every 24 hours. A few more victories like that and it may become easier to buy fake Rolex the old fashioned by -- by seedy looking individuals wearing trench coats.