Respondents to a survey run among silicon.com readers revealed that almost twice as many believe spam is a bigger threat to businesses than the actions of hackers, though viruses take top spot as the biggest worry.
Despite the media hype which surrounds hackers, Kevin Chapman, small business director at security firm Symantec isn't surprised to hear that spam is ranked higher as a concern than hackers.
"I'm not surprised at all," said Chapman. "Spam has now gone way beyond the quick and easy 'hit the delete button and it's gone' solution. It's now a really big problem."
He added: "From the employees' point of view it is about productivity and the sheer annoyance of dealing with all these emails. For the employer it is about bandwidth and other network resources issues."
Martino Corbelli, marketing director for filtering software firm SurfControl, agreed.
"Bandwidth and storage are massive issues for companies. These network resources are not infinite and spam is something which is really starting to anger IT departments," he said.
Both men also agreed that the problems of spam on a network also go far beyond the technical concerns.
SurfControl's Corbelli said: "Some of these spam emails have completely inappropriate content which can create serious problems for the employer on a legal basis.
"There may be somebody who feels they should be protected from pornographic content, for example, and in some cases they may be prepared to sue their employer if they feel they are being exposed to offensive material on the company's network.
"Employers must have systems in place to protect themselves."
However, far and away the biggest concern for computer users is the threat of a virus attack. Among the more than 2,800 respondents to the survey, a massive 71 per cent said they believe viruses pose the biggest threat.
Silicon.com's Will Sturgeon reported from the U.K..