SHANGHAI, June 29 -- ZHOU Feng finds it's more and more difficult to do his e-mail marketing business these days.

Several complaints had been made against his company of sending spam mails and he had to explain to the China Anti-Spam Center that the e-mails sent were not.

His reason: the e-mail users actually had agreed to receive the e-mails when they registered on certain Websites, which have either partnered with his firm or are actually run by his own company.

"In many cases they (the users) wouldn't bother to check carefully the mail sender when their mail boxes are stuffed with spam mails," said Zhou, who has been in the business since 2002.

The first thing many Chinese Web users would do when they arrive at work is to delete the junk e-mails, which have become a serious problem in China where around 60 percent of e-mails users get are junk, according to the Internet Society of China.

Most of the junk e-mails are advertisements, the bulk of which are about online shopping or how to make money on the Internet and sex tools and drugs. They account for nearly 40 percent of all junk messages. What's worse, 11 percent of the junk e-mails also contains virus.

The reason is that hundreds of thousands of small businesses and individuals use aggressive marketing tactics and they choose to ignore the rules as they find what they are doing not risky and quite cost effective.

"Their business cost is almost nothing compared to our way," said Angela Li with Roadway.com.cn, a Shanghai-based e-mail direct marketing site that sends e-mails for Dell, Philips and B&Q.

"We have to rent a third party's platform like DoubleClicks' and pay several fen (one fen equals 0.01 yuan) for each e-mail sent and have to evaluate the opening and forwarding rate of the sent e-mails."

In contrast, the junk e-mail senders just need a software that enables e-mails to be sent to a group of e-mail addresses, plus a "Sniffer" tool which hunts the Web for e-mail addresses, or an e-mail address generator to build an e-mail address database.

The only problem is to find and persuade clients to pay, either for the set of database and e-mail sending software or their service of sending the e-mails on clients' behalf.

The charge is usually only a few hundred yuan for such a set of database and e-mail sending software, which enables the buyers to send their advertisements to millions of e-mail addresses within a short time, according to quotes on several Websites that offer such a service.

Under the shadow of junk e-mails, the e-mail direct marketing service providers are fighting back in cooperation with Web regulators.

"We are in close touch with ISC (about the spam mail issue) and report the spammers if we find them, and we participate in drawing up anti-spam regulations," said Kevin Tang with the Topen Database Marketing which was established in Shanghai in 2004.