The SEC is serious in its effort to combat stock spam -- bulk e-mail messages pushing unknown stocks in get-rich-quick schemes. On Thursday, the federal agency suspended trading for 10 days in 35 stocks highlighted in spam campaigns.

By most accounts, spam now represents roughly 90 percent of all e-mail sent or received on the Internet, with stock-pushing spam accounting for as much as a third of all unsolicited commercial e-mail -- as many as 100 million e-mails each week, according to the SEC.

The kinds of e-mail that the SEC is pursuing usually push a company that has only a relatively small number of shares available to the public. The e-mails are readily recognizable with subject lines such as "Ready to Explode," "Ride the Bull," and the unsubtle "Fast Money."

Those spam victims who do buy the stock often find the value dropping quickly after the spammers have seen a spike in prices and sold their shares. The SEC said this could account for hundreds of millions of dollars in losses.

As one of several examples, the SEC cited Apparel Manufacturing Associates, Inc., which trades as APPM. It closed on a Friday in December of 2006 at $0.06 a share, with 3,500 shares traded.

After a weekend spam campaign, touting "huge news expected out of APPM," it spiked to $0.19 a share on Monday, with nearly 500,000 shares trading, before collapsing back down to $0.10 about a week later.