KnowBe4 Defend Leads Microsoft's Email Security Benchmark Tests

Author : John Brown | Published On : 16 Oct 2026

KnowBe4 has earned the top position across three incremental detection metrics in Microsoft's latest real-world email security benchmark. The company's email security threat detection solution, KnowBe4 Defend, identified malicious messages that Microsoft Defender missed while maintaining a low overlap with Microsoft's detections. The benchmark evaluated seven integrated cloud email security solutions using live Microsoft Defender customer data, highlighting how additional security layers can strengthen protection against sophisticated email-based attacks.

KnowBe4 Defend Delivers Strong Incremental Threat Detection

Microsoft's latest benchmark examined how effectively integrated cloud email security (ICES) solutions detect threats beyond those already identified by Microsoft Defender. KnowBe4 Defend ranked first across all three incremental detection metrics reported in the assessment.

According to KnowBe4, Defend detected 1.11% of malicious emails that Microsoft Defender missed, compared with an average of 0.30% across the evaluated solutions. This result indicates that the platform identified additional malicious messages that the underlying Microsoft security layer did not catch.

KnowBe4 Defend also recorded a 0.65% overlap with Microsoft Defender detections, the lowest among the tested ICES solutions. Low overlap can indicate that an additional security product identifies threats that the primary platform does not already detect.

The platform also accounted for 16.92% of post-delivery malicious email removals, more than double the average reported for the evaluated add-on solutions. This measure highlights its contribution to identifying and removing malicious messages after delivery.

Behavioral Analysis Helps Identify Sophisticated Email Attacks

Cybercriminals increasingly design malicious emails to resemble legitimate business conversations. Attackers may imitate colleagues, executives, suppliers, and trusted partners to persuade employees to open attachments, click links, disclose credentials, or authorize fraudulent transactions.

Traditional email filters often rely on indicators such as known malicious URLs, suspicious attachments, and established threat signatures. Although these methods remain important, attackers can change their techniques to evade detection.

KnowBe4 Defend uses behavioral signals and relationship context to help identify suspicious communications. Rather than examining only an email's technical characteristics, the platform considers patterns that may reveal unusual or deceptive interactions.

Stuart Clark, senior vice president of product at KnowBe4, explained that modern attacks often resemble normal business communication. He said Defend evaluates behavior and relationships rather than focusing exclusively on message payloads.

This approach can help security teams identify suspicious messages that appear legitimate at first glance. It is particularly relevant to business email compromise, impersonation attempts, and social engineering attacks that exploit established business relationships.

Microsoft Benchmark Highlights the Value of Additional Security Layers

Microsoft's benchmark provides organizations with comparative data to assess how third-party email security products complement Microsoft Defender.

Microsoft Defender remains an important component of email protection, detecting and mitigating a substantial share of malicious messages. However, Microsoft's published results also show that integrated security products can provide additional detection capabilities.

Across the evaluated ICES solutions, Microsoft reported average incremental detection of 0.30% for malicious content, 0.52% for spam, and 19.6% for promotional messages. These figures demonstrate that supplementary products can contribute different levels of protection depending on the threat category.

KnowBe4 Defend recorded incremental detection figures of 1.11% for malicious messages, 1.88% for spam, and 65.24% for promotional email. Its low detection overlap with Defender also demonstrates the potential value of adding a complementary detection layer.

Organizations should interpret these measurements within their proper context. Incremental detection rates measure additional findings beyond the primary security platform, rather than the percentage of all malicious email that a product detects independently.

For security leaders, this distinction helps clarify how an additional product may improve an existing email security architecture.

Post-Delivery Protection Supports Faster Threat Response

Email threats do not always become apparent before messages reach employees' inboxes. A message that initially appears harmless may later prove malicious after security researchers identify a threat, investigate a sender, or discover suspicious activity.

Post-delivery detection and remediation allow security teams to respond when new evidence emerges. Removing malicious messages from inboxes can reduce the opportunity for employees to interact with them after delivery.

KnowBe4 Defend accounted for 16.92% of post-delivery malicious removals in Microsoft's benchmark, according to the company's announcement. This result places emphasis on the platform's contribution beyond initial email filtering.

Post-delivery protection can be particularly useful when attackers exploit compromised accounts, impersonate trusted contacts, or adapt messages to evade initial checks.

However, organizations should combine automated remediation with incident response procedures, user reporting, and investigation workflows. These measures help teams assess the scope of an incident and determine whether an employee interacted with a malicious message before its removal.

Security Teams Need Better Protection Against AI-Enabled Attacks

Artificial intelligence has made it easier for attackers to generate convincing messages, imitate writing styles, and personalize social engineering attempts. These capabilities can make fraudulent emails harder to distinguish from genuine business communication.

As a result, organizations need email security systems that evaluate more than suspicious words, attachments, or links. Contextual and behavioral analysis can help identify unusual communication patterns even when an email contains no obvious technical warning signs.

KnowBe4's benchmark results support the case for evaluating security tools based on their ability to detect threats missed by existing systems. Organizations should also assess false-positive rates, integration requirements, investigation workflows, and the operational effort required to manage alerts.

No single security product can eliminate every email threat. A layered approach that combines technical filtering, behavioral detection, employee awareness, multifactor authentication, and incident response provides a more comprehensive defense.

KnowBe4 Strengthens Its Position in Email Security

KnowBe4 provides security awareness training, email and collaboration protection, and other digital workforce security services. The company says more than 70,000 organizations worldwide use its platform to help protect employees and AI agents against evolving threats.

The Microsoft benchmark results give KnowBe4 additional evidence to present to organizations evaluating integrated email security products. Defend's performance across incremental malicious email detection, detection overlap, and post-delivery removals highlights its potential role as a complementary layer within Microsoft-based environments.

For security teams, the findings reinforce the importance of testing products against real-world data and measuring their contribution to existing controls. A solution's value depends not only on the number of threats it detects but also on whether it identifies attacks that other systems miss.

As email-based attacks continue to evolve, organizations will need adaptable security controls that can identify suspicious behavior, respond to emerging threats, and work alongside established security platforms. KnowBe4 Defend's benchmark performance positions it as one option for businesses seeking to strengthen their email threat detection strategy.

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