"When spam clogs our mailboxes, it's annoying. When it rips off investors, it's illegal," SEC Chairman Christopher Cox said in a statement. "Today's trading suspensions, and actions that will follow, should send a clear message to spammers: The SEC will hold you accountable."

The 10-day suspensions took effect Thursday at 9:30 a.m. EST and will terminate at 11:59 p.m. EDT on March 21.

The 35 companies are not exactly household names, but they may ring bells. "Many of these companies are no doubt familiar to anyone who reads their e-mail, because each has been the subject of a spam e-mail campaign," Linda Chatman Thomsen, the director of the SEC's enforcement division, said in a separate statement.

Among the banned-from-trading firms were Apparel Manufacturing Associates Inc., Goldmark Industries Inc., and Healtheuniverse Inc. Those three were singled out by the SEC as examples of what's called "pump-and-dump" scams, where fraudsters buy shares in penny stocks, hype the company in a huge spam campaign, wait for the inevitable increase in trading volume and price, then sell as the price peaks. Investors duped into buying shares by the spam are left holding the bag.

On Dec. 15, the SEC said, shares in Apparel Manufacturing Associates closed at 6 cents, with a trading volume of 3,500 shares. But after a weekend spam run of messages touting, "Huge news expected out on APPM, get in before the wire, We're taking it all the way to $1.00," trading volume the next Monday jumped to 484,568 shares and the price spiked at over 19 cents a share. Two days later the price reached 45 cents. By Dec. 27, though, the price was back down to 10 cents on trading volume of 65,350 shares.