In October, 42.5 percent of all spam originated in the United States, according to a report released Monday by Commtouch Spam Detection Center, which analyzed hundreds of millions of unsolicited messages.
The presidential election was a prevalent theme, said Commtouch Software, an Israel-based antispam software company.
"The intriguing thing about the spam we saw was that it was apparently using politics to sell products and make money more than spreading political ideology or pitching a candidate," Avner Amram, an executive vice president at Commtouch, said in a statement.
Other countries that generated a large volume of spam included South Korea, which was the source of approximately 19 percent, and China, with about 11 percent.
China held onto its top ranking as the country that hosted the most Web sites referenced in the content of the spam. Among the 2.55 million referenced URLs in spam, China accounted for nearly 39 percent, followed by the United States with 31 percent, and South Korea with 21 percent.
The study also found that many e-mails that claimed to comply with the Can-Spam Act were not in fact compliant.
For example, 60 messages from one company with variations on "college degree" as a subject were analyzed by Commtouch. All replies to the senders bounced back, according to the report. Among the various requirements in the Can-Spam Act, unsolicited bulk e-mail must have a functioning return e-mail address.
"The Commtouch Spam Lab team found that numerous spam e-mails would contain images within the e-mail stating that they were Can-Spam compliant," Amram said. "The messages we saw purporting to be Can-Spam compliant didn't even come close to being...compliant."