Why is Europe so popular with spammers?

The latest Sophos ‘Dirty Dozen’ list of those countries which are responsible for the largest amount of spam relaying was published today. While there were no surprises right at the top, apart from the fact that the US has actually managed to pull even further ahead (up from 13.1% of the world’s spam to 15.2%) of the rest of the world which many of us didn’t think was possible, the list does not make good reading for those of us with an interest in domestic web security matters.