Why Email Remains the Top Cybersecurity Risk for IT Leaders

Email remains the most targeted attack surface for organizations. This is true even as IT leaders deploy more advanced defenses.

This article is the first in a five-part series on modern email security strategies. It validates the threat using current data. It explains how attackers operate. It also outlines practical ways to reduce risk.

Future articles will cover authentication, encryption, and advanced threat protection. Each article focuses on helping IT leaders strengthen email security from every angle.

Why Email is Still the Top Risk Vector 

Email continues to be the primary entry point for cyberattacks. 

• 91% of cyberattacks begin with email according to the Verizon DBIR 2024. 

• Business Email Compromise losses exceeded $2.9 billion in 2023. 

• 43% of cyberattacks targeted SMBs last year. 

Filtering and layered defenses alone are no longer enough.

Attackers bypass controls by impersonating trusted domains, vendors, and executives. They rely on social engineering and AI-driven phishing. These tactics target high value users and critical workflows. 

The impact is not just the number of attacks. It is the loss of trust across the 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 is used to create convincing and targeted messages. 

• Exploitation of Misconfigurations:  Gaps in SPF, DKIM, and DMARC enable spoofing and delivery failures. 

• Zero-day Attachments:  Malicious files evade traditional signature-based detection. 

Common Email Attack Vectors and Mitigations 

This table outlines common email attack vectors and the controls used to reduce risk. It can be used to help prioritize security improvements. 

How to Quantify and Prioritize Email Risk 

Measuring email risk helps teams focus on the controls that matter most. 

• Use Microsoft Secure Score to evaluate email-specific controls

• Review anti-phishing policies and authentication settings. 

• Supplement with third-party assessments to identify mail flow issues 

• Identify authentication gaps and BEC exposure. 

• Track incident response times and user susceptibility rates

• Monitor authentication failure trends over time. 

Actionable Steps for IT Leaders 

• 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 simplify Microsoft and help IT teams amplify their impact.

Through strategy, procurement, implementation, and optimization, we help organizations modernize faster. We also help teams stay aligned with Microsoft’s direction across from hybrid environments and the cloud.