Quote:One in every hundred emails sent around the globe has malicious intent, likely to deliver malware, conduct spear-phishing, commit fraud or other activity conducted by cyber criminals.

It's not a theoretical threat, either: recently published documents by the US Department of Justice detail how email played a key role in in the 2014 Sony Pictures breach and other attacks by North Korean cyber attackers. In many cases, it just takes one malicious email being successful to provide attackers with a doorway into the back end of a target network and a route to significant damage.

Researchers at FireEye have examined over half-a-billion emails sent between January and June 2018 and found that one in 101 emails are classed as outright malicious, sent with the goal of compromising a user or network. When spam is discounted, only one third of emails are considered 'clean'.