A secure email gateway (SEG) is an email security solution that filters incoming and outgoing emails to detect suspicious and potentially malicious messages. A secure email gateway blocks common email threats. But it has not kept up with modern email cyberattacks.
How SEGs Work
SEGs scan all incoming and outgoing emails, using a set of rules to determine whether an email is allowed to pass through the gateway to an inbox. SEGs aim to filter out malicious emails and only deliver non-threatening emails. They detect emails with unwanted content like spam, phishing links, or malware.
Once an SEG detects a potential email threat, it blocks the email from being sent and reaching the intended recipient, which reduces the odds that a company will fall victim to an email-based cyberattack because the email was never delivered in the first place.
Common SEG Features
Typical SEG features include
Spam and graymail filtering
Malicious content protection (blocking known malware and phishing links)
Data loss prevention (DLP)
Email encryption
Sandboxing for suspicious attachments
Why SEGs Are Not Enough
While SEGs provide valuable baseline protection, they have significant limitations against modern email threats:
Signature-Based Detection: SEGs rely heavily on known threat signatures, which means they may not detect novel or zero-day attacks that have not been previously identified.
Social Engineering Attacks: BEC, CEO fraud, and other social engineering attacks often contain no malicious links or attachments, making them difficult for SEGs to detect.
Legitimate Infrastructure Abuse: Attackers increasingly use legitimate cloud services and email providers to send attacks, which can bypass SEG reputation checks.
Targeted Attacks: Spear phishing and other highly targeted attacks that are crafted specifically for a particular organization are less likely to match known attack patterns.
The Modern Alternative
AI-native email security solutions like Pangratis use behavioral AI to understand the communication patterns of every employee and detect anomalous messages that deviate from established baselines—catching sophisticated attacks that SEGs miss. Unlike SEGs, which rely on known threat signatures, Pangratis analyzes the content, context, and intent of every email to identify threats regardless of whether they match known patterns.