Email remains the primary communication tool for businesses worldwide, but it also continues to be one of the most exploited attack vectors by cybercriminals. Despite the rise of alternative messaging platforms, organizations still rely heavily on email for external communications, document sharing, and formal correspondence. This ubiquity makes email an attractive target for various threats, from phishing attempts and malware distribution to business email compromise (BEC) attacks and spam campaigns.
Secure email gateway solutions serve as critical infrastructure components that monitor incoming and outgoing email traffic, identifying and blocking potential threats before they reach end users’ inboxes. These specialized security appliances or cloud services act as a barrier between an organization’s email environment and the outside world, employing multiple detection technologies to filter out malicious content. As email-based threats grow increasingly sophisticated, deploying robust email security has become essential for organizations of all sizes across every industry.
The landscape of email-based threats has evolved dramatically over the years:
Early email threats primarily consisted of mass-distributed spam and generic phishing attempts. Today’s attackers often employ highly targeted spear-phishing campaigns that leverage social engineering techniques and detailed information about specific individuals or organizations.
Modern email-borne malware employs advanced evasion techniques, including polymorphic code, fileless malware, and encrypted payloads designed to bypass traditional security controls. The rise of ransomware-as-a-service has made it easier for even non-technical criminals to launch devastating attacks via email.
BEC attacks involve sophisticated social engineering that often doesn’t include malicious attachments or links. Instead, attackers impersonate executives or trusted partners to trick employees into taking actions like transferring funds or sharing sensitive information.
Attackers increasingly target trusted relationships between organizations, compromising legitimate vendor email accounts to distribute malware or phishing attempts that appear to come from trusted sources.
Modern secure email gateways employ multiple layers of protection to address the diverse array of email-based threats:
While often considered merely annoying, spam emails consume bandwidth, waste employee time, and can harbor more serious threats. Advanced spam filtering uses machine learning and reputation databases to identify and block unwanted messages with high accuracy.
Email gateways scan attachments and embedded content for known malware signatures and suspicious code patterns. Modern solutions employ heuristic analysis and behavior-based detection to identify previously unknown threats.
Malicious links are a common attack vector in phishing campaigns. Secure email gateways check embedded URLs against reputation databases and can rewrite links to route through security services that perform real-time analysis when users click.
Beyond scanning for malware, content filtering examines message content for sensitive information, ensuring compliance with data protection regulations and preventing data loss through email.
Suspicious attachments can be automatically detonated in isolated virtual environments to observe their behavior before allowing delivery, catching zero-day threats that might evade traditional scanning.
These email authentication protocols help verify sender identity and prevent email spoofing, a common tactic in phishing and BEC attacks. Secure email gateways can enforce these standards for both incoming and outgoing messages.
Advanced email security solutions can completely remove potentially malicious elements from files and reconstruct clean versions before delivery, eliminating even unknown threats from attachments.
Secure email gateways can be implemented in several ways, each with distinct advantages:
Physical or virtual appliances installed within an organization’s network provide complete control over email security infrastructure and can address strict data sovereignty requirements.
Email traffic is routed through the provider’s cloud infrastructure before reaching the organization’s environment, offering scalability, regular updates, and reduced management overhead.
Some organizations implement both on-premises and cloud components to balance security control with flexibility and redundancy.
Newer approaches integrate directly with cloud email providers like Microsoft 365 or Google Workspace through APIs, offering seamless protection without changing mail routing.
To maximize the effectiveness of secure email gateways, organizations should consider these implementation best practices:
Email gateways should be part of a comprehensive security strategy that includes endpoint protection, user education, and incident response capabilities.
Email security policies should be reviewed and updated regularly to address emerging threats and changing business requirements.
Technical controls should be complemented by regular phishing simulation exercises and security awareness training to help users identify threats that may slip through defenses.
Establish efficient processes for reviewing quarantined messages to minimize both security risks and business disruption from false positives.
Email security data should feed into security information and event management (SIEM) systems and security orchestration platforms for comprehensive threat visibility.
Implement additional controls to detect suspicious login attempts and unusual email account behavior that might indicate compromise.
Despite advances in technology, several challenges remain in securing email communications:
Overly aggressive filtering can result in legitimate messages being quarantined or blocked, potentially disrupting business operations.
Security measures must balance protection with usability to ensure that email remains an effective communication tool.
The rise of encrypted email communications creates blind spots for security tools that cannot inspect encrypted content without compromising privacy.
Small and medium-sized businesses often lack the expertise and resources to properly configure and maintain sophisticated email security solutions.
The prevalence of email access from mobile devices creates additional security challenges, particularly for personal devices outside organizational control.
The email security landscape continues to evolve with several noteworthy trends:
Advanced algorithms now power adaptive protection that can identify anomalous communication patterns and previously unknown threat indicators.
Comprehensive platforms combine traditional gateway functions with newer capabilities like account takeover protection, internal email monitoring, and post-delivery remediation.
Security tools can now continuously monitor delivered messages and retroactively remove threats from inboxes if new information reveals a message to be malicious.
Direct integration with cloud email platforms enables security that works without traditional mail routing changes, offering new deployment flexibility.
Email security is increasingly offered as part of broader security service edge (SSE) or secure access service edge (SASE) frameworks that protect all communication channels.
Organizations should regularly assess their email security posture using metrics such as:
Secure email gateways remain an essential component of organizational cybersecurity strategies. As email-based threats continue to evolve in sophistication and impact, these specialized security solutions provide critical protection against one of the most persistent attack vectors. By implementing robust email security with multiple layers of protection, organizations can significantly reduce their exposure to phishing, malware, business email compromise, and other email-borne threats.
While technology plays a crucial role, effective email security requires a comprehensive approach that combines technical controls with user education, strong policies, and regular assessment. Organizations that prioritize email security not only protect themselves from potential breaches but also safeguard their communications, maintain customer trust, and ensure business continuity in an increasingly threatening digital landscape.
About Sasa Software
Sasa Software specializes in the development of software solutions for the protection of computer networks from file-based attacks. Founded in 2013 as a spin-off of a US Army contractor, Sasa Software, with its CDR-based Gatescanner suite, has been recognized by Gartner as a ‘Cool Vendor in Cyber-Physical Systems Security’ (2020), and by Frost & Sullivan as ‘Asia Pacific ICT (Critical Infrastructures) Security Vendor of the Year for 2017’.
