Spam accounted for 87 percent of all email messages in 2009, says Symantec.
According to the security vendor's December State of Spam and Phishing report, spam peaked in May, when it accounted for 95 percent of all email messages sent and was at its lowest level (74 percent) at the beginning of the year, just months after US ISP McColo was shut down.
However, the death of the King of Pop, Michael Jackson, generated the most celebrity spam in 2009. According to Symantec, the levels of Jackson-related spam accounted for just under two percent of all spam messages.
Symantec said it expects 2010 to be an active year for spammers, with botnets playing a heavy part in distribution of spam.
The security vendor also revealed spammers will continue using tactics such as URL shortening services such as bit.ly and free web hosting servers to evade detection by antispam filters.