The Securities and Exchange Commission has taken a step toward combating stock spam, the unsolicited bulk e-mail message that promotes cheap stocks for quick profits, which usually prove illusory.

Starting an enforcement effort it is calling Operation Spamalot, the S.E.C. suspended trading in 35 stocks that had been promoted in recent spam campaigns. The suspensions will last for 10 days. The S.E.C. said that further investigation could lead to arrests.

Spam over all has swelled during the last six months, and now accounts for more than 90 percent of all e-mail messages, according to the Internet security firm Secure Computing. Stock spam has been a significant contributor to that growth and now accounts for 30 percent of all spam, the company said.

The e-mail messages seek to persuade recipients to buy shares in a company, generally one that has few shares available to the public. The spammers buy shares before they send out their e-mail messages, then sell when the price rises. The victims who buy the stock typically see the value of their shares fall drastically.