7 Email Security Metrics That Matter: How to Measure and Improve Your Protection

Despite the evolution of security tools and protocols, email continues to be the primary entry point for cyberattacks. Today’s threats go far beyond spam and malware—they’re socially-engineered, highly targeted, and designed to bypass traditional defenses.

To stay ahead, you need more than intuition. You need data.

Tracking the right email security metrics helps you measure your current defenses, identify gaps, and continuously improve. But not all metrics are created equal—especially when traditional solutions overlook modern threats.

Here, we explore seven key metrics that provide deep insight into your detection speed, response capabilities, and areas of risk—empowering you to improve outcomes and better protect your organization.

Speed is a critical factor in email threat detection. The sooner a malicious message is identified, the less likely it is to cause harm. Mean Time to Detect or MTTD measures how long it takes from the moment a malicious email is delivered to when it's identified as a threat. The longer it goes undetected, the more opportunity the attacker has to engage the target, steal credentials, or move laterally within the environment.

While traditional secure email gateways (SEGs) focus on pre-delivery prevention, modern solutions like Abnormal operate in a post-delivery context—detecting and mitigating threats that bypass initial controls. In this environment, MTTD becomes a vital measure of risk. Reducing it can significantly limit exposure and impact. Minimizing MTTD requires efficient triage workflows and the ability to quickly identify behavioral anomalies. Teams that monitor this metric can benchmark detection speed, uncover workflow gaps, and prioritize automation or training to improve performance.

Quick detection is important—but what happens next matters just as much. Mean Time to Respond or MTTR captures the full scope of your response, from first action to final containment. For email attacks, this may involve notifying affected users, removing malicious messages across inboxes, and locking down compromised accounts.

A lower MTTR indicates a well-integrated and responsive process—from investigation through to complete containment. Tracking this metric helps identify delays, process gaps, or tooling limitations that could allow threats to persist longer than necessary.

Detection isn’t just about finding threats—it’s about finding the right ones. Accuracy plays a critical role in both protecting users and maintaining trust in your security systems. False positives are legitimate emails incorrectly flagged as threats. False negatives are malicious messages that go undetected. Both create problems: false positives disrupt business and erode trust in security tools, while false negatives expose the organization to real danger.

Tracking both rates helps balance detection accuracy and operational efficiency. Ideally, your tools should block threats without overwhelming teams with noise or interfering with normal communication. Understanding these error types can guide tuning efforts and evaluate overall tool performance.

End users can be a helpful line of defense, but they shouldn’t carry the full weight of threat detection. Monitoring how frequently employees report suspicious emails offers insight into both user awareness and the performance of your security tools. A high report rate often signals strong engagement, which is positive—but it may also indicate that too many threats are reaching inboxes or that users are over-reporting due to unclear guidance or lack of confidence. In some cases, it could mean that your security awareness efforts, while well-intentioned, are generating excessive false positives. This creates more work for the security operations center (SOC), potentially slowing incident response and increasing operational overhead.

Monitoring this metric helps you evaluate the right balance between education and automation. It also highlights opportunities to improve threat prevention, reduce user burden, and streamline investigation workflows.

While reporting rates reveal user vigilance, click rates show how often users fall for phishing attempts. Together, they offer a fuller picture of how employees respond to threats in real time. The end-user click rate measures how frequently recipients engage with malicious links or attachments—whether in real attacks or simulated phishing tests. A higher rate may suggest gaps in awareness training, overly convincing lures, or insufficient filtering that allows dangerous messages through.

This metric helps teams identify risk-prone user groups, refine education programs, and assess whether phishing simulations are translating into safer behaviors. Over time, a declining click rate signals progress toward a more security-aware workforce.

When a user clicks a malicious link or unknowingly shares credentials, the next phase of the attack often unfolds behind the scenes. That’s where account takeover detection becomes essential. As attackers move beyond traditional phishing to more stealthy, credential-based compromises, it’s critical to track signals that indicate unauthorized access. Metrics like unusual login behavior, privilege escalations, and MFA bypass attempts can help surface compromised accounts before damage spreads.

These insights extend your visibility beyond the inbox, revealing how attackers may be moving laterally or exploiting internal accounts. Monitoring account takeover attempts is key to detecting post-click activity and reducing the risk of broader compromise.

Beyond individual incidents, understanding the overall makeup of threats targeting your organization provides a strategic advantage. Tracking email volume by threat category—such as credential phishing, business email compromise (BEC), malware, or graymail—helps paint a clearer picture of your evolving risks. It enables teams to prioritize detections, allocate resources effectively, and tailor awareness training to reflect the threats users are most likely to encounter.

Over time, this view becomes a powerful tool for spotting trends and communicating risk to leadership in a more data-driven, contextual way.

The right metrics don’t just track performance—they tell the story of your security posture. They reveal where your defenses are working and where attackers may be slipping through. Most importantly, they empower you to make smart, data-informed decisions that continuously improve your program.

Take stock of where you stand today. Start tracking these metrics. And turn your email security from reactive to resilient.

Interested in learning more about how Abnormal provides resilient email security? Schedule a demo today!