Blaming an over-reliance on the SMTP mail protocol Tom Gillis, IronPort marketing vice president, said the basic lack of identity and reputation of e-mail senders exacerbates the issue.

To overcome spam, Gillis said the entire industry needs to change the underlying infrastructure of e-mail, adding that the new wave of secured e-mail will be based on three core factors: identity, reputation and policy.

"We believe the root cause associated with all the things that slow e-mail down is in the SMTP protocol itself as it was designed when the Internet was a communication vehicle for scientists; the things that make e-mail successful are the things that make it vulnerable today," Gillis said.

"The key tool is adopting the notion of sender reputation because it is simple - if you look at the behavior of the entity, mail or Web server, past performance is a good indicator of the future - all the industry is gravitating around the reputation of the sender, because it is much harder to spoof."

Ambika Gadre, IronPort director of information services, said 80 percent of spam now contains a URL, so tracking the reputation of spam senders is important.