The nation's first federal law regulating spam, called the Can-Spam Act, took effect Jan. 1, 2004, and set off a string of lawsuits and new state regulations criminalizing unsolicited bulk e-mail.

The year also marked the 10th anniversary of the first spam message, in what continues to be a serious threat to the efficacy of e-mail.

Despite the many efforts to curb spam, it continued to swell. In North America, spam accounted for 38 percent of the 31 billion e-mails sent each day this year, up from 24 percent in 2002, market researcher IDC reported.

More than ever, spam threatened to foil the utility and sheer enjoyment of e-mail, a 33-year-old communication wonder that's only been popularized in the last decade. People were more cautious this year about opening suspicious attachments, clicking on e-mail links or giving out their addresses online.

Momentum built this year for e-mail authentication standards to ensure that senders of e-mail are who they say they are. Major Internet and software companies, including Microsoft, Yahoo and America Online, pushed new technical standards to help separate the wheat from the chaff in e-mail. Giants like AOL eventually began testing Microsoft-backed Sender ID, a technical system for identifying the source of an e-mail.

Even tech giants like Amazon.com lobbied the government to take action and support more rapid development of new e-mail standards.

Still, Microsoft's effort to convince the Internet Engineering Task Force to adopt its patented technology for e-mail authentication failed in September amid concerns it would cede too much control over the future of worldwide correspondence to one company.

Prosecutors also brought many successful lawsuits under the federal Can-Spam Act for the first time. The Justice Department, federal prosecutors and several corporations filed criminal charges against spammers who falsified headers, tried to mislead consumers and used false information when buying a domain or signing up for a Web mail account.

In one example, a Southern California man pleaded guilty to spamming people through unprotected hot spots.

Meanwhile, Maryland became the first state to pass legislation to criminalize fraudulent e-mail following the enactment of the Can-Spam Act. In April, the government recommended stiff penalties for people convicted under the law.

Still, the new spam law's criminal sanctions did not stem the flow of bulk solicitations.

Antispam experts warn that 2005 will be the year of the professional virus, or viruses written by engineers with a profit motive that's largely derived from spam. But, they say, security systems will be more robust to fend off threats coming in through the Web, downloadable software and e-mail. Already the industry has consolidated to build multipronged software packages. AOL bought Mailblocks; Symantec acquired Turntide; and Microsoft bought anti-spyware firm Giant Company Software, among other acquisitions and new products.

--Stefanie Olsen and Rob Lemos