McAfee research shows that every single year, spam emits carbon dioxide in the amount equivalent to 3.1m cars. Nearly 80% of spam-related energy is wasted when spam messages are deleted and when users are searching for right emails. This amount of energy is equivalent to what 2.4m American households use.
The report points out that when in November 2008 McColo web page, responsible for spam generation, was closed down, the amount of spam in the world wide web dropped by 70% from one day to the next. It can be compared to removing 2.2m cars from the roads. McAfee suggests that anti-spam filters eliminate 75% of such emails but much better effect is achieved when spam sources are removed.