Spam emails use up an estimated 33 terawatt hours of power each year,
according to a report on the state of the spam industry by security vendor
McAfee.
The
Carbon
Footprint of Email Spam Report (PDF) states that 62 trillion spam emails
were sent in 2008, and that the energy used to send and delete them could power
2.4 million American homes. Each spam email generates 0.3 grams of carbon, the
report said.
McAfee estimates that, while spam filters can cut the carbon footprint of
spam by 75 per cent, it is far better to shut down spam at the source. The
closure of the
McColo
spam operation last year caused a dramatic drop in spam levels, which had an
unexpected environmental benefit.
"The most obvious benefit of the McColo shutdown for practically anyone with
an email address was an immediate reduction in unsolicited junk messages," the
report said.
"At the same time, the planet experienced a less obvious environmental
benefit. For every spam email not sent, an associated reduction in electricity
use, and therefore carbon emissions, took place."
Overall, the McColo shutdown saved the equivalent energy of taking 2.1
million cars off the road.
Businesses are also taking a financial hit from spam, the report said. A
typical medium sized firm uses 50,000 kilowatt hours to run its email system,
but over a fifth of that power is used to deal with spam.
The average business email user is responsible for 131Kg of CO2 per year in
email-related emissions, and 22 per cent of that is spam related. Users viewing
and deleting spam is the largest energy drain associated with spam, at almost
18 billion kilowatt hours or 52 per cent of total spam energy.
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