According to a survey by e-mail filtering company, MessageLabs, more than 80% of e-mails sent to manufacturing companies last year were spam. It also found that viruses were an increasing problem.
While the government and public sector saw the least spam (20%), the worst affected sectors were recreation (74%), retail (64%) and chemicals & pharmaceuticals (64%).
The sector survey also found that viruses was a growing problem. The charity/non-profit sector was the worst affected at 17%, compared with 11% for the government and public sector.
It found that the professional services, such as legal firms, were the best protected with only 2.5% of e-mails containing a virus. The financial services came in in second with 3.5%.
Meanwhile, 10% of e-mails received in the retail sector had viruses, education had 8% and the building and construction sector had 7%.
Mark Sunner, MessageLabs chief technology officer, said, "The convergence of viruses and spam is now dominant - almost all viruses released in 2004 contained some additional component allowing the infected machine to become a spam-sending zombie."
Such "zombies" allow hackers to remotely send spam from infected machines without the infected user knowing.