August 21, 2025 2 Minute Read

• MailMarshal's new D-Fence layer uses machine learning to combat sophisticated phishing attacks by analyzing email structure and identifying hidden malicious elements.
• D-Fence provides next-generation email security by catching 40% more phishing emails that previously went undetected.
• D-Fence works with URLDeep to deliver powerful phishing and email security, using advanced machine learning to detect both new and never-before-seen threats.

Trustwave, A LevelBlue Company, is proud to unveil D-Fence, a powerful new machine learning-based anti-phishing layer now seamlessly integrated into MailMarshal that captures 40% more phishing emails. This capability is needed now more than ever as phishing attacks are among the top three attack vectors, according to the FBI.

Designed to supercharge your email security, D-Fence brings next-generation phishing protection for MailMarshal to the fight against phishing attacks by delivering smarter, faster, and more adaptive protection.

Smarter Threat Protection

Harnessing the power of advanced machine learning, D-Fence analyzes unique features from every email, from header structures to HTML patterns, embedded links, and even hidden code.

Instead of just looking at what a phishing email says, D-Fence understands how it’s built and where it comes from.

D-Fence identifies traits attackers can’t disguise, even when the content itself changes. This is accomplished by targeting the infrastructure behind phishing campaigns, such as Phishing-as-a-Service (PaaS) kits, malicious hosting services, and compromised email delivery platforms.

What We’re Already Seeing

Since D-Fence’s integration into MailMarshal, it has demonstrated clear improvements in catching sophisticated phishing attacks, including:

• Campaigns sourced from PaaS platforms
• Emails with From line trickery, including obscure, overly long, or deliberately malformed, to mislead users in email clients
• HTML obfuscation, such as zero-width characters and HTML entity encoding to evade filters

• Non-English phishing attempts targeting global user bases
• Attacks sent via legitimate services like Amazon Simple Email Service (SES)
• Callback phishing with no URL, only a phone number or an image attachment prompting user action.

Double the Analyzing Power

D-Fence works in tandem with URLDeep, MailMarshal’s deep learning-powered URL analysis engine. Together, these two machine learning layers provide unmatched coverage.

D-Fence examines an email’s structural elements to detect phishing without relying solely on content or known signatures, and URLDeep uses deep learning to detect new, never-before-seen malicious URLs.

This dual-layered ML approach adds a powerful dimension to MailMarshal’s already robust PhishFilter engine, which also includes proven heuristics and signature-based detection.

Proven Impact

Trained on Trustwave’s vast datasets of real-world phishing threats and continuously updated by our SpiderLabs threat researchers, D-Fence boosts MailMarshal’s detection rate from 99.9% to 99.94%, catching 40% more phishing emails. that previously slipped through.

D-Fence is Already Working for You

MailMarshal clients that have PhishFilter enabled have automatically been upgraded to D-Fence. It’s a silent but powerful guardian, delivering next-generation phishing protection without changing your workflows.

What Trustwave MailMarshal Delivers

With D-Fence in place, the MailMarshal email security service is now more efficient and capable, adding to its ability to deliver maximum granular control of your email traffic with powerful rules-driven policy management, helping you catch threats that others miss, preventing data loss, and easing implementation and administration.

MailMarshal:

• Protects against Ransomware, Business Email Compromise (BEC), Phishing, Malware, and Zero-Day.
• Zero Clients reported ransomware infection in 20+ years.
• 99.99% Malware and exploit capture rate.
• < 0.001% spam false positives.
• Layered threat intelligence, powered by telemetry from 5,000+ global MSS/ MDR clients and ML-powered algorithms.

Stay Informed

Sign up to receive the latest security news and trends straight to your inbox from Trustwave, A LevelBlue Company.