Why Email Remains the Top Cybersecurity Risk for IT Leaders

Email remains the most targeted attack surface for organizations. This has not changed, even as IT leaders deploy more advanced defenses. 

This is the first article in a five-part series on modern email security. It covers the current threat landscape, how attackers operate, and where to start reducing risk. Future articles will address authentication, encryption, and advanced threat protection. 

Why Email is Still the Top Risk Vector 

Email is the primary entry point for cyberattacks. 

• 91% of cyberattacks start with email (Verizon DBIR 2024). 

• $2.9 billion in reported losses from Business Email Compromise in 2023.

• 43% of cyberattacks targeted small and mid-sized businesses last year. 

Filtering and layered defenses alone are no longer enough. Attackers now impersonate trusted domains, vendors, and executives. They use AI-driven phishing to target high-value users and critical workflows. 

The damage goes beyond attack volume. It erodes trust across the entire organization. 

Key Tactics Used by Attackers 

Attackers rely on a small number of repeatable techniques: 

• Impersonation:  Attackers mimic executives, vendors, or internal users to deceive recipients. 

• AI-Driven Phishing:  Machine learning generates convincing, targeted messages at scale. 

• Configuration Gaps:  Errors in SPF, DKIM, and DMARC records enable spoofing and delivery failures. 

• Zero-Day Attachments:  Malicious files bypass traditional threat detection methods. 

Common Email Attack Vectors and Mitigations

Use this table to prioritize security improvements based on your organization's current exposure.  

How to Quantify and Prioritize Email Risk 

Measuring email risk helps teams focus on the controls that matter most. Three approaches are worth using together: 

• Microsoft Secure Score: Evaluate email-specific controls, including anti-phishing policies and authentication settings.

• Third-Party Assessments: Surface mail flow issues, authentication gaps, and BEC exposure that internal tools may miss.

• Incident Tracking: Monitor response times, user click rates, and authentication failure trends over time.  

Actionable Steps for IT Leaders 

Start here to reduce email risk across your environment. 

• Audit and align SPF, DKIM, and DMARC across all domains. 
• Deploy Microsoft Defender for Office 365 for layered protection. 
• Prioritize high-risk users and sensitive financial workflows. 
• Run regular user awareness training and phishing simulations. 
• Integrate with a SIEM for alerting and incident response. 
  

About the Sourcepass Center of Excellence for Microsoft 

The Sourcepass Center of Excellence for Microsoft is a certified Microsoft Solutions Partner. We help IT teams simplify Microsoft and amplify their impact. 

Our services span strategy, procurement, implementation, and optimization. We help organizations modernize and stay aligned with Microsoft’s direction across from hybrid and cloud environments.