Agari, a provider of real-time data-driven security solutions, has raised $15 million in Series C funding led by Scale Venture Partners, with participation from existing investors Alloy Ventures, Battery Ventures and First Round Capital, among others. Agari has now raised about $23 million in venture funding; its Series B funding in early 2013 brought in $5.25 million at a valuation of over $20 million. The company's software collects data on emails that a business's consumers receive, then analyzes and categorizes that data to help detect and stop third-party domains that send cyberthreats. Agari has doubled its client base and tripled its revenue in the past year. As part of the funding, Ariel Tseitlin of ScaleVP will join the Board of Directors.