A study has blamed spam for the production of more than 33bn kilowatt-hours of energy every year, enough to power more than 2.4m homes, the BBC reports.
The report, The Carbon Footprint of e-mail Spam, estimated that 62 trillion spam emails are sent globally every year. Climate consultants ICF International and anti-virus firm McAfee carried it out. The report found the spam amounted to emissions of more than 17 million tons of CO2.
Searching for legitimate e-mails and deleting spam used some 80% of the energy: the study found that the average business user generates 131kg of CO2 every year, of which 22% is related to spam.
ICF say that spam filtering would reduce unwanted spam by 75%, the equivalent to taking 2.3 million cars off the road, but argues that while spam filtering is effective in reducing energy waste, fighting it at the source is far better plan.
The report highlights the case of McColo, a US web hosting firm that had ties to spammers. The day after it was taken offline by its two internet service providers, global spam volume fell by 70%.
Although the respite was only temporary, McAfee said the \'day without spam amounted to talking 2.2 million cars off the road\' and that tackling spam should be part of the campaign to reduce carbon emissions.
The BBC points out that the Spam Report is published days after Symantec\'s bi-annual Internet Security Threat report, which found that spam had increased by 192%, with bot networks responsible for approximately 90% of all spam e-mail.
Spam analyst Richi Jennings said that while McAfee and Symantec had different ways of measuring spam, he was in total agreement with the bot network figure.
He was reported by the BBC saying, \'The vast majority of spam is sent via botnets. We\'ve got Conficker building a fantastic network and you can bet your bottom dollar that it will wind up being used to send spam.
\'There is speculation that the botnet Conficker is building up is owned and run by the owners of another active botnet - Waledac, itself probably connected to the classic Storm botnet - and the theory is that the owners are keeping their powder dry at the moment and will activate it once Waledac goes down.\'