Fewer spam emails are clogging up inboxes than ever in the last 12 years, according to Symantec, which warned other forms of malware are on the rise.
The overall rate of junk messages fell to 49.7 per cent in June - the first time the total has dipped below the halfway mark since 2003, the security company said in its Symantec Intelligence Report.
The figure is the latest in a downward trend, with 52.1 per cent of emails being spam in April, falling to 51.5 per cent in May.
However, on 18 July some 61 per cent of 17 billion emails constituted junk, the research revealed.
Symantec pointed to a police crackdown on botnet networks, as well as European ISPs sharing information on identified botnet networks in an effort to block them, as the main reasons behind the drop.
Phishing emails also fell, from one in 1,865 emails in May to one in 2,448 in June.
Other forms of malware are on the rise, however, as cyber criminals seek alternative ways to target internet users.
A total of 57.6 million new malware variants were created in June, up from 44.5 million in May and 29.2 million in April.
"This increase in activity lends more evidence to the idea that, with the continued drops in email-based malicious activity, attackers are simply moving to other areas of the threat landscape," wrote Symantec.
These areas include ransomware, which crept from a 12-month low in April to reach 477,000 attacks in June.
Crypto-ransomware, where hackers encrypt victims' data until a fee is paid, was also up in June to reach its highest level in six months.
