Proofpoint ZenGuide Report Suspicious (formerly PhishAlarm) is a Gmail add-on that allows your users to alert security and incident response teams to suspected phishing emails. This is a valuable addition to security awareness and training programs as early reporting of suspicious emails can dramatically reduce the duration and impact of an active phishing attack. 

A free component of Proofpoint's simulated phishing assessments, Report Suspicious allows users to draw on their knowledge to stop social engineers and hackers in their tracks. As a behavior reinforcement tool, Report Suspicious further strengthens the Continuous Training Methodology by capitalizing on awareness and understanding of phishing issues, and allowing end users to actively apply best practices in defense of their data and systems.

Note: Proofpoint ZenGuide Report Suspicious requires a license.