SLE (Secure Letter Email) is a next-generation Secure Email Gateway (SEG) engineered to detect and block advanced persistent threats (APTs), zero-day malware, malicious attachments, and phishing documents before they reach the user.

At the heart of SLE lies SecuLetter’s proprietary assembly-level reverse engineering engine, which analyzes email attachments at the binary level — far deeper than signature- or behavior-based systems.

Unlike traditional sandboxing tools, SLE does not require file execution or external cloud access. It offers pre-delivery threat detection with exceptional speed and precision, making it ideal for sensitive environments such as government, finance, and national infrastructure.

📌 Key Features:

• Detects obfuscated malware in Office, PDF, HWP, archive formats

• Integrates with cloud threat intelligence for URL and sender-based filtering

• Blocks threats before they are delivered to end-users

• Immune to evasion tactics that bypass sandbox or behavioral systems

• Flexible deployment: inline or at MTA level (supports MS Exchange, M365, etc.)

🛡️ Best Suited For:

• Organizations requiring pre-execution threat blocking in secure communications

• Sectors with strict email security compliance: public agencies, finance, energy

• Enterprises replacing legacy SEG solutions with high-precision detection

SLE enables organizations to intercept malicious payloads in real-time, eliminate false negatives, and protect employees from even the most sophisticated email-borne attacks — all without disrupting normal email flow.