"That's because spam has a sizable carbon footprint -- using 33
billion kilowatt hours (KWh) each year, according to a report by
security vendor McAfee.
"But McAfee also said that if every inbox were protected by a
state-of-the-art spam filter, the energy required to deal with spam
could be reduced by 75 percent -- the equivalent of taking 2.3
million cars off the road. That's because filters use less energy
than humans do.
"Humans delete each spam individually, taking up to three
seconds per spam e-mail. Machines are more efficient and filters
account for only about 16 percent of annual spam energy use, the