A secure email gateway (SEG) or a secure email server (SEC) is a type of email security software that sits between inbound and outbound email communication. Every email sent to and from an organization passes through this email security gateway to ensure that its contents are not malicious or a sign of a data leak. It prevents unwanted emails in user inboxes, such as spam, phishing emails, and malware. In many ways, email gateways are the first line of defense for email security.

SEGs are crucial in defending against various email-borne threats. They offer several main features to enhance email security, including sandboxing, content disarm and reconstruction (CDR), data loss prevention (DLP), anti-phishing measures, and post-delivery protection. Here's a detailed look at each of these features:

1. Sandboxing

Sandboxing involves executing suspicious email attachments or links in a controlled, isolated environment to observe their behavior. This helps in detecting zero-day exploits and sophisticated malware that traditional signature-based defenses might miss. The sandbox mimics a real user environment to analyze the potential impact without risking the actual network.

2. CDR

CDR is a proactive security measure focusing on the content of emails. It involves analyzing and breaking down the content to identify and remove any potentially malicious code. The clean content is then reconstructed into a safe version before delivery. Unlike traditional detection methods, CDR doesn't rely on detecting known threats but instead ensures that all delivered content is safe.

3. DLP

DLP systems are designed to prevent sensitive information from being sent outside the organization unintentionally or maliciously. SEG DLP features scan outgoing emails for predefined patterns that match sensitive data, such as personal information, financial details, or proprietary information. If such data is detected, the email can be blocked, quarantined, or encrypted before sending.

4. Anti-phishing

Anti-phishing mechanisms in SEGs are essential for protecting users from deceptive emails designed to steal sensitive information like login credentials or financial information. These features typically include:

• URL scanning: Checking links within emails against databases of known phishing sites.
• Machine learning algorithms: Analyzing email content for characteristics typical of phishing attempts.
• User awareness: Flagging suspicious emails to alert recipients or automatically quarantining them.

5. Post-delivery protection

Post-delivery protection addresses threats identified after an email has been delivered to the user's inbox and includes:

• Retrospective analysis: Re-scanning emails as new threat intelligence becomes available.
• Automated remediation: Removing or quarantining emails that are identified as malicious after delivery.
• User reporting mechanisms: Allowing users to report suspicious emails, which are then analyzed, and necessary actions are taken to mitigate the risk.

SEG can be useful against the following threats:  

1. Phishing

Phishing involves fraudulent attempts to obtain sensitive information by disguising itself as a trustworthy entity in electronic communication. SEGs protect against phishing by:

• Scanning email content and links for phishing indicators.
• Using machine learning algorithms to identify phishing patterns.
• Blocking or quarantining suspected phishing emails.

2. Spear phishing

Spear phishing is a targeted type of phishing in which cyber criminals tailor their messages to a specific individual or organization. SEGs combat spear phishing by:

• Analyzing email headers, content, and sender behavior.
• Detecting anomalies that suggest a spear phishing attempt.
• Employing advanced threat intelligence to identify and block such targeted attacks.

3. Malware and ransomware

These threats involve malicious software that can infect a system, encrypt files, and demand a ransom. SEGs address malware and ransomware by:

• Scanning attachments and links for known malware signatures.
• Using sandboxing to execute and analyze suspicious attachments in a controlled environment.
• Applying CDR to neutralize potentially malicious code.

4. Spam

Spam refers to unsolicited bulk emails that can clutter inboxes and potentially contain malicious links or attachments. SEGs manage spam by:

• Employing robust spam filters that use heuristics, blocklists, and content analysis.
• Continuously updating spam detection algorithms to adapt to new spam techniques.
• Ensuring legitimate emails are not falsely flagged as spam (reducing false positives).

5. Business email compromise (BEC)

BEC is a type of phishing attack where attackers impersonate business executives to trick employees into transferring money or disclosing sensitive information. SEGs protect against BEC by:

• Analyzing email content and context to identify impersonation attempts.
• Implementing policy-based controls to flag or block emails that violate organizational norms.
• Utilizing machine learning to recognize and alert regarding anomalous communication patterns.

6. Data leakage

Data leakage involves the unauthorized transmission of sensitive information outside the organization. SEGs prevent data leakage by:

• Implementing DLP features to scan outgoing emails for sensitive information.
• Blocking, quarantining, or encrypting emails that contain sensitive data.
• Enforcing policies to ensure compliance with data protection regulations.

7. Zero-day exploits

Zero-day exploits are attacks that exploit previously unknown vulnerabilities. SEGs defend against zero-day exploits by:

• Using sandboxing to detect and analyze unknown threats in a controlled environment.
• Applying heuristic and behavioral analysis to identify suspicious activity.
• Updating threat intelligence continuously to adapt to emerging threats.

8. Email spoofing

Email spoofing involves forging the sender's address to make an email appear as if it is from a legitimate source. SEGs prevent spoofing by:

• Implementing authentication protocols like DMARC (Domain-based Message Authentication SPF (Sender Policy Framework), Reporting & Conformance), and DKIM (DomainKeys Identified Mail).
• Verifying the sender's authenticity before delivering emails to the recipient.

9. Account takeover

Account takeover occurs when attackers gain unauthorized access to email accounts. SEGs mitigate this threat by:

• Monitoring for unusual login attempts and access patterns.
• Implementing multifactor authentication (MFA) to secure email accounts.
• Alerting administrators and users to suspicious activities.

10. Advanced persistent threats (APTs)

Sophisticated, sustained, and targeted cyber-attacks aimed at stealing data or surveilling a specific organization are called APTs. SEGs counter APTs by:

• Continuously monitoring email traffic for signs of APT tactics, techniques, and procedures.
• Employing advanced analytics and threat intelligence to detect long-term, low-and-slow attacks.
• Coordinating with other security tools to provide a comprehensive defense.

SEG

A secure email gateway (SEG) or a secure email server (SEC) is a type of email security software that sits between inbound and outbound email communication. Every email sent to and from an organization passes through this gateway to ensure its contents are not malicious or evidence of a data leak. It prevents unwanted emails in user inboxes, such as spam, phishing emails, and emails containing malware. In many ways, email gateways are the first line of defense for email security.

ICES

The difference between ICES and SEG is that ICES solutions protect cloud environments that can be on-premise or hybrid. ICES uses machine learning and natural language processing (NLP) and connects via API to understand an organization's email activity and protect against advanced phishing attacks. Unlike SEGs, which use a database of known threats, ICES has the capability to identify never-before-seen threats and socially engineered phishing emails.

Why is an email security gateway important for organizations?

Email security is essential to protecting organization networks from malicious cyber-attacks and safeguarding sensitive information. Secure email gateways prevent malicious emails from gaining entry and compromising the network through processes such as filtering, blocking, and quarantining. There are multiple reasons why a robust email security gateway is critical for organizations.

Reasons to ensure that your organization's system includes a secure email gateway include:

• Increased protection against cyber-attacks: Filtering out email threats before they reach user inboxes reduces the risk of data breaches.
• Reduction of spam: Reducing the volume of unsolicited emails blocks potentially harmful spam.
• Prevention of data loss: Including rules that ensure sensitive data cannot be shared provides better data protection and regulatory compliance.
• Enhanced compliance with regulatory requirements: Ensuring that robust email security measures are in place is required by regulatory bodies of many industries.
• Higher user productivity: Filtering out spam and irrelevant, potentially harmful emails limit distractions so employees can remain focused on their work.

How does an email security gateway help prevent phishing attacks?

An email security gateway is an advanced digital shield between incoming emails and a user's inbox. It delivers optimized email security by detecting, blocking, and mitigating phishing attempts to safeguard organizational data.

Although there are many approaches to safeguarding emails from phishing attacks, not all email security systems are the same. Darktrace's comprehensive approach uses advanced Self-Learning AI technology to counter this common cyber-threat. This smart automation continuously adapts to recognize individual user patterns and evolves to identify new threat variants. Even slight deviations in a user's regular patterns indicate a phishing attempt.

Other ways that email security gateways protected by Darktrace / EMAIL  prevent phishing attacks include:

• Real-time threat response: Darktrace ensures that email phishing attempts are detected and responded to in real time. The system continuously updates in order to counter new and unfamiliar phishing tactics.
• ICES: Darktrace detects and mitigates phishing threats using a combination of behavior and signature-based detection techniques to scrutinize incoming emails for malicious content.
• Detecting specific phishing types: Darktrace email security gateway quickly identifies known phishing strategies such as spear phishing, whaling, and BEC. As leaders in the field of advanced AI technology, Darktrace's email security gateway technology is primed to detect emails from fraudulent sources that try to trick users into sharing sensitive data or information.
• Analyzing sender behavior: Darktraces email security system examines user behavior and email content for indications of malicious intent to identify patterns that may indicate a phishing attempt.

Darktrace has developed a fundamentally different approach to email security, one that doesn’t learn what’s dangerous from historical data but forms an in-depth understanding of each organization and its users.

Darktrace / EMAIL focuses on individuals - how each person uses their inbox and what constitutes “normal” for each user - in order to detect what’s not normal. Our AI technology builds profiles for every email user, including their relationships, tone and sentiment, content and link sharing patterns, and thousands of other signals.

To learn more about Darktrace / EMAIL read our Solution Brief.