UPDATED: As if the constant deluge of spam filling inboxes were not intrusive enough, a new report shows spammers are sending huge amounts of unsolicited ads through instant messaging services, a practice known as spimming.

The report, conducted by the Pew Internet & American Life Project, revealed that more than one-third of the 134 million American adults who use the Internet, also use instant messaging services. Of those 52 million people, nearly one-third have received unsolicited commercial through their instant messages.

That means approximately 17 million adults have received the instant-message version of spam.

"It is not surprising that they do this," said Anne Mitchell, president of the private Institute for Spam and Internet Public Policy. "The typical spammer is absolutely going to exploit any possible soft spot, and the clever ones, in it for the long haul, are going to create soft spots."

Results from the telephone poll, conducted from Jan. 13 to Feb. 9, showed that younger Internet users are more likely to get spim. That is probably because they more often use instant messaging.

Nearly 40 percent of users under 30 who use instant messaging have gotten spim. The number of users from aged 30 to 49 who have received spim is 27 percent.

The poll also showed that broadband users were not any more likely than dial-up users to receive spim, even though those with broadband connections often keep their instant message programs running for longer periods of time than dial-up users, according to the report.

In all, 2,201 adults 18 and over took part in the telephone survey. The results for the spim findings have a margin of error of +/- 5 percentage points.

The report comes the same week Federal prosecutors made the first criminal case involving this new form of spam.

As reported by internetnews.com, Anthony Greco, 18, of Cheektowaga, N.Y. was arrested at Los Angeles International Airport, where prosecutors said they lured him from his upstate New York home in a sting operation. He was charged with violating the CAN-SPAM Act.

The survey did not ask what type of unsolicited commercial messages were contained in the spim. But it did reflect the large difference in age groups that use instant messaging.

Sixty-six percent of Internet users under age 30 use instant messaging, whereas 35 percent do so who are over age 30. Internet users from relatively poor households are among the most likely users of IM, according to the study. Fifty-two percent of online adults who live in households earning less than $30,000 use instant messaging.

Lee Rainie, director of the Pew Internet & American Life Project, said the correlation between low-income households and high instant messaging usage is likely a result of young adults who are only beginning their careers.