Spam is not only growing in volume, but it's also becoming harder to distinguish from legitimate email, according to an online survey of U.S. consumers by Harris Interactive. The survey was commissioned by Cloudmark, an anti-spam and email security firm.

In the Harris survey, 42 percent of U.S. adults said they've received more spam over the past 12 months than they had previously -- a trend in keeping with an earlier report by Cisco (NASDAQ: CSCO), which said the global volume of spam is up 30 percent from 2009.

Complicating matters, the Harris survey found that among U.S. adults who had ever received a spam email, 33 percent said that they found it more difficult to figure out what's a legitimate mailing and what's a message from a scammer or rogue marketer.


While it's primarily directed at consumers, spam is also a big issue for IT, since many employees can check personal accounts while at work -- accounts that aren't as well protected as corporate email and which could expose them to malicious links and other threats.

Although spam started out as, and often still is, relatively innocuous mass market emails, security firms have long warned that spam can also include links to malware sites and other dangerous content.

Despite the risks, spam still manages to dupe a large portion of the online public. In the Harris survey, 38 percent of U.S. adults who had received spam email said they had also at least once responded to spam messages. And of those who responded to spam, 55 percent said the two most common results they experienced were that they either received more spam or contracted a computer virus.

Among the various threats posed by spam, having their computer infected by a virus was the most widespread fear among U.S. survey respondents, with 74 percent of them citing it as a key worry. The second most common fear was identity theft, at 56 percent.

"This survey demonstrates that there is still much work to be done to protect consumers from spam and the threats that it brings with it," Leon Rishniw, senior vice president of engineering for Cloudmark, said in a statement. "Not only must users adopt the necessary technologies to fortify their defenses against email threats, they also must be more vigilant about opening and responding to messages only from known senders."

Fortunately, many users are heeding the word, with the Harris survey reporting that a majority of consumers have taken action to try to manage or minimize the impact of spam. In the U.S., 43 percent said they have created separate email accounts for activities they think might attract spam. Also, a majority of U.S. and European adults surveyed (68 and 60 percent, respectively) said they had anti-spam protection installed on the computer they use for email.

Still, despite the risks and the growing deluge of spam landing in their inboxes, many users are less likely to be flummoxed by spam than they are by missing legitimate emails: According to Harris, 65 percent of respondents in the U.S. said that they felt receiving a spam message was preferable to not receiving an email from a legitimate sender.

David Needle is the West Coast bureau chief at InternetNews.com, the news service of Internet.com, the network for technology professionals.