Spam Email Equals Emissions From 3 Million Cars

by | Apr 15, 2009

carbon_footprint_spam_2New research shows that, on a global basis, e-mail spam uses uses 33 billion kilowatt hours (KWh) annually.

That’s enough to power 2.4 million homes, with the same GHG emissions as 3.1 million passenger cars using 2 billion gallons of gasoline, according to a press release

The study, “Carbon Footprint of Spam,” was produced by McAfee Inc.

Here are additional findings from the study:

  • The average GHG emission associated with a single spam message is 0.3 grams of CO2, or the same as driving three feet (one meter. However, when multiplied by the yearly volume of spam, it is equivalent to driving around the earth 1.6 million times
  • Much of the energy consumption associated with spam (nearly 80 percent) comes from end-users deleting spam and searching for legitimate e-mail (false positives). Spam filtering accounts for just 16 percent of spam-related energy use.
  • Spam filtering saves 135 TWh of electricity per year. That is equivalent to taking 13 million cars off the road.
  • If every inbox were protected by a state-of-the-art spam filter, organizations and individuals could reduce today’s spam energy by 75 percent or 25 TWh per year, the equivalent of taking 2.3 million cars off the road.
  • Countries with greater Internet connectivity and users, such as the United States and India, tended to have proportionately higher emissions per e-mail users. The United States for example, had emissions that were 38 times that of Spain.
  • While Canada, China, Brazil, India, the United States and the United Kingdom had similar energy use for spam by country, Australia, Germany, France, Mexico and Spain tended to come in about 10 percent lower. Spain came in at the lowest, with both the smallest amount of e-mail that was received as spam and the smallest amount of energy use for spam per e-mail user.


Companies increasingly are finding ways to reduce energy used on computers.

Virtualization, or having several users running off a single desktop, is one emerging method to reduce carbon emissions and electricity usage.

Additionally, Microsoft has released the results of a comparative carbon footprint study that quantifies the environmental benefits by providing software online, instead of on a disc, with associated packaing. The digital distribution study, based on the online download of 10 million copies of Microsoft Office 2007, avoided eight times the amount of carbon emissions, or reduced the total tons of carbon emissions by 88 percent, compared to producing and shipping a DVD and its associated packaging through traditional retail distribution channels.

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