Email Penetration Testing: Your Strongest Defense Against Phishing

In today’s connected world, email is still the easiest way for attackers to get into your business. Even with good security practices in place, phishing and spoofing tactics continue to catch employees off guard—and a single mistake can have major consequences. By taking a proactive approach, you can strengthen your defenses, protect sensitive data, and cut down your risk of costly attacks like Business Email Compromise (BEC). 

There’s a reason email is still the number one way hackers attack businesses: it works. Email remains the most common communication tool at work and cybercriminals are getting smarter about using it against us. 

No matter how strong your firewalls are, all it takes is one convincing email to trick someone into clicking a malicious link, handing over credentials, or authorizing a fraudulent payment. 

 And the following numbers highlight this: 

• 91% of cyber-attacks start with a phishing email¹ 

• 68% of breaches involve human error, often due to social engineering² 

• Business Email Compromise (BEC) scams have caused over $50 billion in reported losses worldwide³ 

While cyber security awareness training for employees is essential, it’s not enough by itself. Without regularly putting your defenses to the test through real-world scenarios, your business stays vulnerable. 

Email penetration testing isn’t just one thing but usually covers a few different types of checks. On the one side, you’ve got phishing simulations that test how staff respond to suspicious emails, and on the other, there are technical reviews that look under the hood at how your email systems are set up. This may mean reviewing your Microsoft 365 or Google Workspace settings or checking whether your domain can be spoofed due to misconfigured DNS records. When done together, both human and technical gaps can be highlighted. 

Unlike standard phishing tests that focus on click-through rates, true email pen testing takes a broader, more realistic approach. It evaluates both human and technical layers of your email security, providing a clearer picture of how well your defenses would hold up against a real attack. 

At Target Defense, we simulate social engineering threats that mirror the tactics used by today’s threat actors. This includes assessing how susceptible your employees are to phishing, how easily someone could spoof a trusted sender like your CEO or finance team, and whether your domain protections are properly configured to prevent misuse. 

The goal isn’t to catch people out; it’s to give your organization a practical, real-world understanding of where your email security stands today, where the gaps are, and how to close them before someone else tries to exploit them. 

Many companies already have security tools like spam filters, multi-factor authentication (MFA), and employee training. So why are phishing attacks still so successful? 

Here’s the reality: 

Spam filters miss things: Sophisticated phishing emails often use trusted domains or familiar names to sneak past filters. It’s worth noting that phishing assessments won’t always reflect this risk accurately as test domains are usually whitelisted, so red teaming or advanced simulation is required to assess defences. 

MFA isn’t foolproof: Especially when using less secure methods like email-based MFA. Techniques like session hijacking and adversary-in-the-middle (AiTM) attacks can sometimes bypass weaker implementations. 

Email authentication can be misconfigured: If your SPF, DKIM, or DMARC records aren’t set up correctly, attackers can easily spoof your domain. 

Training can only go so far: Even well-trained employees can fall for a realistic scam—especially under pressure. 

The best way to stay ahead of threats is to test your defenses the way real attackers would. 

At Target Defense, we approach email security testing with the mindset of a real-world attacker, but with the ethics and experience of CREST-certified professionals. 

Scoping and Planning 

We collaborate with your team to define goals and map out realistic attack scenarios based on your business and threat profile. 

Reconnaissance 

Using open-source intelligence (OSINT), we gather public information to craft highly targeted phishing and spoofing emails that mimic real-world threats. 

Attack Execution 

We launch simulated attacks such as phishing emails, executive impersonations, and more, to test both employee responses and technical safeguards. 

Technical Review 

We evaluate your SPF, DKIM, and DMARC settings to spot misconfigurations that could leave your domain vulnerable to spoofing. 

Detailed Reporting 

You’ll receive a clear, easy-to-follow report that highlights vulnerabilities, explains the potential risks, and gives you actionable steps to tighten your defenses. 

Our goal is simple: help you find and fix weaknesses before a real attacker can exploit them. 

Identify vulnerabilities before attackers do 

Real-world attack simulations help uncover weaknesses across your people, processes, and technology before a bad actor does. By proactively identifying these gaps, you can address them early and reduce the risk of a costly breach. 

Test employee awareness safely 

Phishing simulations let you see how employees respond to realistic threats without any real-world fallout. These insights help you spot risky behaviors, identify who needs additional training, and build a stronger security culture across your organization. 

Harden your domain security 

Your email authentication protocols (SPF, DKIM, and DMARC) play a key role in protecting your brand. Email pen testing verifies that these controls are set up correctly and working as intended to stop attackers from spoofing your domain or impersonating trusted contacts. 

Protect against Business Email Compromise (BEC) 

BEC attacks are among the most damaging and costly cybercrimes. Simulating these scenarios helps you understand your current exposure to financial fraud and data theft and implement targeted defenses to reduce the risk. 

Strengthen training and policies 

Testing doesn’t just highlight vulnerabilities; it gives you actionable data to enhance your training programs and refine internal policies. Over time, this helps foster a more security-conscious workforce and a more resilient security posture overall. 

Email remains one of the most common and most effective tools cybercriminals use to breach businesses. Even with solid security measures in place, evolving phishing tactics and human error continue to create opportunities for attackers. 

Taking a proactive, real-world approach to testing your email security is one of the most effective ways to close those gaps. By identifying and addressing weaknesses before they’re exploited, you give your business the best chance to stay secure, protect sensitive information, and build long-term resilience against ever-changing threats.