The number of unique new unsolicited e-mail (spam) messages has risen 42 percent from 350,000 per day at the end of 2003 to 500,000 a day by the end of June, according to anti-spam vendor Commtouch Software.

And while 49 countries have been identified as hosting Web sites referenced in spam e-mails, China is still the host for 73.5 percent of such sites, Commtouch said in a statement Wednesday. Spammers include those site links to provide more information regarding their products, or to allow users to buy the products online.

Following the introduction in the U.S. on Jan. 1, 2004 of the Controlling the Assault of Non-Solicited Pornography and Marketing (CAN-SPAM) Act, almost 10 percent of spam now complies with this regulation, Commtouch, based in Netanya, Israel, said.

Other findings by the company include:

• 56 percent of global spam e-mail originates in the U.S. and 80 percent originates from the top five spam countries, which include South Korea (10 percent), China (6.6 percent), Brazil (3.4 percent) and Canada (3 percent.)

• promoting drugs is the aim of 30 percent of all spam, with Viagra alone accounting for 14.1 percent of spam.

• spam is becoming more sophisticated in order to beat content filters, with 21.6 percent of global spam messages including visible random characters in the subject, body or both.

• 5.8 percent of spam is written in a language other than English.

The U.S.'s relatively lenient spam regulations have come in for criticism from user organizations. The Coalition Against Unsolicited Commercial E-Mail (CAUCE) has urged the U.S. to enforce an opt-in policy, by which all spam is forbidden except that which a user has expressly signed up for.

"Without a registry through which consumers, businesses and nonprofit organizations could preemptively protect themselves from the incessant barrage of e-mail advertisements, there is no reason to believe that the current barrage of spam -- estimated by some organizations as being roughly three-quarters of all e-mail sent in May 2004 -- will decrease any time soon," CAUCE said in a statement recently.

Australia's spam legislation came into effect in April, with fines of up to A$1.1 million [m] (US$790,000) per day capable of being levied on violators.