Email is how business gets done around the world, making it the perfect target for business email compromise (BEC). Yet unlike most cyberthreats, BEC rarely announces itself. There’s no malicious attachment to quarantine, no dangerous link to block. Instead, an attacker sends a plain, well-worded email—a message that looks exactly like the everyday correspondence your employees trust—and asks someone to do something entirely routine: pay an invoice, update banking details, buy gift cards, or forward a sensitive file. The whole scam hinges on impersonation and timing, not code.
What is business email compromise?
At its core, BEC is a confidence trick delivered by email. An attacker either spoofs or compromises a legitimate-looking account—often that of a CEO, CFO, vendor, or trusted partner—and uses it to manipulate an employee into transferring money or data. Common variations include CEO fraud (a spoofed executive urgently requesting a wire transfer), vendor or invoice fraud (a supplier’s real account is hijacked and payment redirected to a fraudulent account), payroll diversion, and gift card scams. Increasingly, attackers do their homework first, studying an organization’s org chart, vendor relationships, and even writing style so their requests feel authentic.
What makes BEC so dangerous is precisely what makes it hard to catch. These messages frequently carry no payload at all—no malware, no phishing URL—so signature-based defenses and traditional secure email gateways often wave them through. The FBI’s Internet Crime Complaint Center has tracked BEC as one of the costliest cybercrimes for years, and the trend keeps climbing: losses moved from $2.94 billion in 2023 to $2.77 billion in 2024 and back up to $3.04 billion in 2025. The average loss per complaint now exceeds $122,000, and 86% of BEC funds move via wire transfer or ACH—meaning these attacks land squarely inside real financial workflows, where a single successful message can cost an organization six or seven figures.
Why BEC is getting harder to stop
Two forces are making the problem worse. First, attackers have gone payloadless by design, stripping out the technical indicators that security tools are built to detect and leaning entirely on social engineering. Second, generative AI has lowered the barrier to entry: threat actors can now craft flawless, context-aware lures at scale, personalize them across languages, and eliminate the grammatical tells that once gave phishing away. The result is a higher volume of more convincing attacks arriving faster than any human team can manually review.
That combination is why detection increasingly depends on advanced AI. But AI alone introduces its own challenge—an overwhelming volume of data to interpret and a high number of false positives that require continual tuning and human oversight. Chasing false alarms burns analyst time and erodes trust in the very tools meant to help. The answer isn’t AI in isolation, but a layered approach that identifies anomalies and suspicious emails through AI-driven detection while grounding those decisions in threat intelligence, email authentication protocols, reputation checks, and proven detection signatures.
What to look for in a BEC protection solution
When deciding how to safeguard against BEC attacks, organizations should look for a solution that:
- Understands intent, not just keywords. It should identify anomalous activity and build a social graph of user interactions, analyzing risky phrases and semantic intent to determine an email’s true purpose—since a BEC message often looks perfectly normal on the surface.
- Combines AI with proven indicators. Rather than relying solely on AI to spot patterns and abnormalities, effective protection pairs machine learning with signatures and threat feeds, so attacks are stopped at the point of detection.
- Explains what it blocked and why. Security teams should be able to easily triage each detection and see not only which policy triggered it, but the specific risky characteristic that drove the decision.
- Makes policy modeling simple. Through historical analysis of past messages, teams should be able to gauge the impact of a policy change and understand which messages would be caught at each level of sensitivity before flipping the switch.
- Addresses the human element. Because BEC targets people, the strongest programs pair technical controls with user awareness—flagging risky messages in context and coaching employees toward safer decisions over time.
How Mimecast helps stop BEC attacks
Mimecast delivers such an approach for organizations of all sizes, which can be particularly valuable for small businesses that must operate with limited IT and security resources. Mimecast Advanced BEC Protection uses AI to analyze communication patterns, writing styles, and contextual clues, blocking threats that go well beyond malware or phishing links. BEC protection now detects impersonation and social engineering attacks across 20 languages, with detection rates improving continuously as the system learns from emerging attack patterns observed across Mimecast’s global threat intelligence network of more than 1.7 billion emails inspected per day.
With Mimecast, AI is much more than a last line of defense—it becomes an integral part of daily operations, protecting systems and people from BEC and other threats like phishing, spear phishing, and ransomware. The billions of signals crossing Mimecast’s Human Risk Command Center strengthen AI detection to continuously identify and block advanced attacks, while Multi-Vector Threat Protection correlates signals across multiple detection mechanisms to catch coordinated campaigns that isolated security engines miss.
Learn more about how Mimecast can help your organization stop business email compromise.
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**This blog has been updated from a previous version.