Internet users in Idaho, Alabama and South Carolina receive a higher percentage of spam messages in their inboxes than residents in other U.S. states, according to the latest report from security software vendor Symantec's Message Labs Intelligence group.

The report also found that e-mail accounts at small to midsize businesses around the country are targeted with more spam than large enterprise customers, a trend that figures to continue as SMBs often lack the IT resources to invest in top-tier security applications installed by their larger brethren.

"Spam isn't just a simple annoyance to businesses, but a real threat that can consume resources and put valuable information at risk regardless of location," Paul Wood, a senior analyst at Symantec's MessageLabs Intelligence group, said in the report. "From the World Cup to fake PDF Reader updates, even the most intricate scams are now widespread and the sheer size and power of today's botnets are making possible what was once unthinkable."

Idaho, the potato capital of the universe, was a runaway leader in the spam to non-spam e-mail ratio for the second year in a row, checking in at 95.2 percent. Alabama checked in at 94.4 percent, followed by South Carolina (93.6 percent), Indiana (92.7 percent) and Tennessee (92.1 percent).

The rest of the Top 10 states targeted by spammers includes Illinois, Utah, Washington, New Hampshire and North Carolina, all of which reported a much higher rate of spam than the national average of 89.3 percent, according to Symantec.

Meanwhile, Montana, Louisiana and Puerto Rico were the least-targeted U.S. states and territories last year.

By industry, the report found that spammers zeroed in on companies in the engineering, automotive and construction sectors with the most frequency while the least-spammed verticals included finance, administration and the public sector.

That spammers are spending more time using botnets and other malware-laced e-mails on SMBs is both good and bad news. It's good news for large companies, their employees and their customers because it's clear that the investments made in enterprise-class antispam and antispyware applications are having the intended effect of driving spammers elsewhere.

On the other hand, smaller businesses, which according to Panda Security's latest security report often lack even the most basic understanding of how malware is disguised and spread, continue to be peppered with spam campaigns of all types.

"Areas with greater populations of [SMBs] are likely to receive the greatest proportion of spam," the report concluded. "Similarly, the least spammed areas are often home to some of the largest companies. For smaller businesses, spam drains valuable resources such as bandwidth, processing power and employee productivity."

Symantec officials said about 90 percent of the 120 billion spam e-mail messages sent each day come from organized botnets comprised of an estimated 5 million to 6 million spam-sending computers.