E-mail worms, not long ago the scourge of the Internet, have declined sharply in 2007, a security company has revealed. According to UTM security vendor Fortinet, the incidence of mass-mailing worms has declined by 5 percent each month since the start of the year, putting the once-feared worm well below other types of attack in terms of volume.

The figures come from the company's The State of Malware report for June 2007. Viruses, spyware and software exploits have remained roughly stable in volume throughout the same period, while Trojans have been climbing since February to represent the number one threat.

Much less common mobile, IM, Linux, and non-mailed Win32 worms have all shown marked declines, albeit from relatively low levels.