As spam moves from nuisance to serious problem, spending on systems to fight the menace of unsolicited email will rocket, analysts have predicted.

According to a study by IDC, worldwide revenue for anti-spam packages will exceed $1.7bn in 2008 compared to $300m in 2003.

The analyst firm said that the development of spam from a mere nuisance to an increasingly serious and expensive problem is the driver behind explosive revenue growth, innovation and investment in the market.

"The spam problem is being brought under control as a direct result of investments in commercial anti-spam solutions during the past two years," said Mark Levitt, IDC research vice president for collaborative computing.

IDC security products research manager Brian Burke added that the next several years will show continued improvements in reducing the costs of spam.

Progress will depend on how "quickly and well anti-spam offerings keep up with the latest spam innovations and are deployed and managed with antivirus as core elements of broader network security solutions," said Burke.

Anti-spam offerings will continue to converge with overall email content security, IDC predicts. The analyst suggested that two out of three executives view anti-spam applications as part of a larger network security framework.