California took a tough stand against spam e-mail on Wednesday after Governor Gray Davis signed a law prohibiting anyone from sending unsolicited commercial e-mail advertisements to a California e-mail address.

The law sets up an "opt-in" requirement, the aim being to prevent e-mail users from getting e-mail advertisements unless they asked to be on the sender's list. Senders of unsolicited messages could be held liable for damages up to $1,000 for each message to an individual and up to $1 million for each e-mail advertisement sent out. The recipient, the state attorney general or the e-mail service provider could seek damages.

The law also bans sending spam from California and prohibits the collection of e-mail addresses or registering multiple e-mail addresses for the purpose of sending spam. It passed the state Senate on Sept. 11 as Senate Bill 186. Another bill, Senate Bill 12, which proponents said would have allowed Internet service providers to be held liable for spam, died in an state Assembly committee in July. The author of that bill, State Senator Debra Bowen of Redondo Beach, said Microsoft had spearheaded an effort to defeat it. Microsoft denied the charge.

The law is set to take effect Jan. 1, 2004.

Microsoft sees the law as a positive step, according to spokesman Sean Sundwall. The company has taken several steps to keep spammers from taking advantage of its Hotmail service, he said. If a spammer uses such a service to send unwanted e-mail, "that's the fault of the spammer, not the fault of the ISP," Sundwall said.

Its provision for individuals to sue over spam makes this law stand out, said commentators familiar with the legal issues.

Unscrupulous spammers who are hard to track down are unlikely to knuckle under, but the law should have some effect on both senders and recipients of commercial e-mail, they said.

"I don't think this is the silver bullet to spam. You're still going to want e-mail filters and you're still going to receive spam from parts unknown, but this will make a dent," said David Kramer, a partner at the law firm Wilson, Sonsini, Goodrich and Rosati, in Palo Alto. Companies that may have been on the fence about whether to send unsolicited commercial e-mail now have a clear sign that it is illegal and the potential for lawsuits will enter the cost equation, he said.

The IDG News Service is a Network World affiliate.