The number of unsolicited e-mails received in the US appears to be falling thanks to new laws and better technology, a government report says.
Surveys show internet users are becoming more tolerant of spam
The Federal Trade Commission (FTC) said internet users still disliked spam - but most got less than two years ago.
Spam filters and a 2003 US law allowing people to opt out of future mailings were helping cut the problem, it said.
However, the report warned spammers were improving their technology and the number of e-mail scams had risen.
The US CAN-Spam legislation (Controlling the Assault of Non-Solicited Pornography and Marketing Act) was introduced in the US in January 2004.
The FTC said a survey by e-mail filtering firm MX Logic found spam accounted for 67% of traffic through its system for the first eight months of 2005 - a 9% drop from a year earlier.
Time Warner's internet unit AOL reported a 75% fall in spam received by its members from 2003 to 2004, the report added.
The FTC said studies from other countries, including Canada and Finland, "similarly report a decrease in the amount of spam reaching consumers' inboxes".
Most retailers and marketers were complying with legislation under CAN-Spam which allowed consumers to opt out of future mailings, it said.
Surveys also showed users were becoming more tolerant of spam, seeing it as "an acceptable nuisance rather than a cause for abandoning e-mail".
Internet service providers (ISPs) had improved their filters, the FTC said, and could now effectively block the vast majority of spam messages.
However, the government report warned, there has been a troubling shift in spamming techniques over the past two years.
"Spam advertising commercial products or services is being replaced by spam that is potentially more harmful, as opposed to merely annoying," it said.
"For example, phishing spam, which attempts to trick recipients into providing personally identifiable information to scam artists posing as legitimate businesses, has increased significantly since the enactment of CAN-Spam."