Business Green: Anyone with an email account knows that spam is a nuisance, but as well as wasting time unsolicited emails are also guilty of wasting huge quantities of energy, according to new research released today. The study from environmental research firm ICF was commissioned by security software firm McAfee and found that the 63 trillion spam email messages sent each year waste 33 terawatt hours of energy, or enough to power 2.4m homes. The research also assessed the carbon footprint …