Letting users flag postings they recognize as spam.Using a CAPTCHA to stop automated posting tools.Requiring users to register with a valid email address.Blocking excessive posts from a single IP address.This year, the spammers started winning and are taking over Craigslist. Spam on Craigslist has been a minor nuisance for years. Perhaps that's why I was so disturbed by John Nagle's wartime narrative of the raging battle between Craigslist and spammers. I consider Craiglist a generally benevolent public service. Unfortunately, these same characteristics also make Craigslist a particularly juicy target for spammers and evildoers.
Have you ever used Craigslist? It's an almost entirely free, mostly anonymous classified advertising service which evolved from an early internet phenomenon into a service so powerful it is often accused of single-handedly destroying the newspaper business.