- An estimated worldwide total of 62 trillion spam emails were sent in 2008.
- Global annual spam energy use totals 33 billion kilowatt-hours (KWh), or 33 terawatt hours (TWh). That’s equivalent to the electricity used in 2.4 million homes in the United States, with the same GHG emissions as 3.1 million passenger cars using two billion United States gallons of gasoline.
- The average GHG emission associated with a single spam message is 0.3 grams of CO2. That’s like driving three feet (one meter) in equivalent emissions, but when multiplied by the annual volume of spam, it’s like driving around the Earth 1.6 million times.
- On November 11, 2008, McColo Inc., a United States-based web hosting provider notorious for its prolific contribution to email spam, was taken offline by its upstream Internet Service Provider (ISP). Overnight, global spam volume dropped by 70 percent. The energy saved in the ensuing lull — before spammers rebuilt their sending capacity — equated to taking 2.2 million cars off the road.
I'm a long time participant in Project Honeypot, which works to identify email address harvesters and spam senders by posting "honeypot" email addresses and mail servers, kind of like bait cars used in sting operations to find car thieves.