The U.S. state of California has taken a tough stand against spam email after Governor Gray Davis signed a law prohibiting anyone from sending unsolicited commercial email advertisements to any California email address.

The law, which will take effect on January 1st 2004, sets up an ‘opt-in’ requirement, the aim being to prevent email users from getting advertisements unless they asked to be on the sender's list.

Senders of unsolicited messages could be held liable for damages up to US$1,000 for each message to an individual and up to $1 million for each email advertisement sent out. The recipient, the state attorney general, or the email service provider could seek damages.

The law also bans sending spam from California and prohibits the collection of email addresses or registering multiple email 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 a 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. "I don't think this is the silver bullet to spam. You're still going to want email 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 California.

Companies that may have been on the fence about whether to send unsolicited commercial email now have a clear sign that it is illegal and the potential for lawsuits will enter the cost equation, he said.