An undisclosed strategic investor and venture capital firms Alloy Ventures, Battery Ventures, First Round Capital and Greylock Partners have invested $5m in Agari, a US-based email security service.
In November 2011, Agari, which was formerly known as Authentication Metrics, raised $2.5m in its series A round from the VC firms.
Agari was formed out of technology first created by IronPort Systems, and further developed at network equipment provider Cisco after it acquired IronPort Systems in 2007.
On a daily basis, Agari protects more than 2.3 billion emails, stopping over four-million suspicious emails and detecting over 40,000 malicious website links.
Ingrum Putz has also joined the company as vice-president of engineering and Vidur Apparao as chief technology officer.