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.

While checking the gmail spam folder, I decided to count them in miles from now :(

McAffee: The Carbon Footprint of Email Spam Report