In my previous blog article, I mentioned that there were 10 big components to an email security tech stack. For the sake of tech sprawl, many companies are choosing to combine these big components into one: the Secure Email Gateway (SEG).

A Secure Email Gateway (SEG) can encapsulate many, but not all, of the components of a comprehensive email security tech stack. SEGs are designed to prevent unwanted email and deliver good email to the user’s mail server, acting as a critical defense layer against spam, phishing, malware, and other email-borne threats. They typically include spam filters, malware and ransomware protection, phishing protection, data loss prevention (DLP), and email encryption capabilities. However, the extent to which they cover each area varies by solution, and some aspects of a full email security strategy extend beyond the scope of what a SEG can provide.

SEG Coverage of Email Security Layers:

1. Spam Filters: Yes, a primary function.
2. Phishing Protection: Yes, through various detection techniques.
3. Malware and Ransomware Protection: Yes, typically includes scanning and sandboxing.
4. Data Loss Prevention (DLP): Often included to some extent, but capabilities can vary.
5. Encryption: Yes, usually supports TLS and may offer additional encryption options.
6. Email Authentication: Yes, supports SPF, DKIM, and DMARC validation.
7. Threat Intelligence Sharing: Partially, through integration with external threat intelligence feeds.
8. User Training and Awareness: No, this is typically outside the scope of SEGs and requires separate initiatives.
9. Archiving and Backup: No, these functions are generally provided by separate solutions.
10. Incident Response and Reporting: Partially, SEGs can automate some responses and reporting, but comprehensive incident response involves more extensive processes and tools.

What Are Some Popular SEGs Out on the Market?

There are many popular SEGs out on the market, and if you are looking for one, be sure to run a POC that covers the key considerations for SEG buyers. Here are some popular secure email gateways:

Proofpoint Email Protection: Proofpoint Email Protection provides comprehensive defense mechanisms against a variety of email threats. It is designed to detect and block malicious emails while providing tools for data loss prevention, email encryption, and targeted attack protection. Proofpoint utilizes advanced machine learning, along with signature-based and reputation-based techniques, to accurately identify threats. It also offers granular visibility and control over email messages, enabling organizations to tailor their security settings to their specific needs.

Mimecast Email Security Cloud Gateway: Mimecast’s Secure Email Gateway is known for its comprehensive protection against both known and emerging email threats. It leverages sophisticated detection techniques, including signature-based, behavioral analysis, and machine learning, to offer strong defenses against spam, malware, phishing, and targeted attacks. Mimecast also emphasizes resilience, ensuring email continuity even during attacks or system failures. Additionally, it offers targeted threat protection, URL protection, attachment protection, and impersonation protection services.

Barracuda Email Security Gateway: Barracuda Email Security Gateway offers a powerful, easy-to-use solution designed to protect email inboxes from a wide array of threats including spam, phishing, viruses, and spyware. It features inbound and outbound filtering capabilities, data loss prevention, and email encryption, ensuring that sensitive information remains secure. Barracuda’s gateway also emphasizes simplicity in deployment and management, making it accessible for businesses of all sizes. Advanced threat detection capabilities help identify and block sophisticated attacks before they reach users.

What Doesn’t SEG Cover for Complete Email Security?

Secure Email Gateways (SEGs) play a crucial role in defending against a wide range of email threats, including spam, phishing, malware, and more. However, while SEGs are an essential component of an organization’s email security strategy, they are not a panacea. There are several areas where SEGs may fall short in providing complete email security:

1. Advanced Threats Beyond Initial Delivery: SEGs are most effective at intercepting threats at the point of email delivery. However, they may be less effective against sophisticated attacks that leverage social engineering or advanced persistent threats (APTs) that do not rely on traditional malware delivery mechanisms. This includes threats that evolve or are activated after the initial email has passed through the gateway.

2. Internal Email Threats: Many SEGs focus on inbound email threats and may not adequately address internal threats, such as emails sent from one compromised user account within an organization to another. This can be particularly problematic for insider threats or lateral movement within a network after an initial breach.

3. Encrypted Email Threats: As more organizations adopt end-to-end encryption for email communication, SEGs face challenges in inspecting the content of encrypted emails. While encryption enhances privacy and security, it also creates a blind spot for SEGs, which rely on content inspection to identify threats.

4. Fileless Attacks and URL-based Threats: SEGs may struggle with detecting fileless attacks and malicious URLs that do not involve traditional malware. Attackers increasingly use sophisticated techniques to bypass static filters, including dynamically changing URLs and leveraging legitimate services for malicious purposes.

5. Post-Delivery Threat Discovery: New threats or previously unknown malware variants may be identified after an email has already been delivered to a user’s inbox. SEGs typically do not address the need to retrospectively remove or quarantine emails that were initially deemed safe but are later discovered to be malicious.

6. User Behavior and Targeted Phishing Attacks: SEGs cannot fully mitigate the risk posed by user behavior, such as the clicking of malicious links or the provision of sensitive information in response to spear-phishing or business email compromise (BEC) attacks. These types of attacks often rely on social engineering techniques that exploit human vulnerabilities rather than detectable malware signatures.

7. Comprehensive Data Loss Prevention (DLP): While many SEGs include some DLP capabilities, they may not offer the comprehensive DLP features required to prevent the leakage of sensitive information. Advanced DLP solutions can provide more granular control and detection capabilities for data in motion, at rest, and in use.

Addressing These Shortcomings

To overcome these limitations, organizations often complement their SEG with additional layers of security, including:

• Advanced Threat Protection (ATP) solutions that use behavioral analysis and machine learning to detect sophisticated threats.
• Internal email monitoring tools to detect threats within the organization.
• Endpoint detection and response (EDR) solutions to identify and mitigate threats on individual devices.
• Security awareness training to educate users on identifying and responding to phishing and other social engineering attacks.
• Integrating SEGs with other security tools for a more comprehensive security posture, including SIEM systems for better visibility and incident response.

While an SEG forms a critical part of an enterprise’s email security strategy, comprehensive protection against all potential email threats often requires additional tools and practices, especially in areas like user training, archiving, and incident response.

In the next blog post, I will cover some popular tools to address these shortcomings, some alternatives to SEGs, as well as what they mean for average people and enterprises.