Secure Email Gateway (SEG) is a security control that inspects inbound and outbound email to stop phishing, malware, spam, and data loss. If you’re asking what is Secure Email Gateway, it’s the policy and inspection layer between your mail system and the internet—protecting users and brands before threats hit inboxes.
SEGs can run as cloud services or appliances. They analyze headers, content, links, and attachments using signatures, reputation, sandboxing, and machine learning. On the outbound side, they enforce data loss prevention (DLP), encryption, and authentication standards like SPF, DKIM, and DMARC—reducing spoofing and ensuring deliverability. We often see organizations pair SEG with native M365/Google defenses to close gaps against targeted attacks (BEC, credential phishing) and to meet compliance.
Key capabilities include:
- Threat filtering: Phishing, malware, spam, and URL rewriting.
- DLP & encryption: Prevent sensitive data leaks and secure messages.
- Authentication controls: SPF, DKIM, DMARC enforcement and reporting.
- Quarantine & reporting: User-friendly release, audit trails, and metrics.
Our take? A modern SEG turns the busiest attack channel into a managed, measurable control point.
Exploring the right balance of protection and usability? Start with our Secure Email Gateway (SEG) Guide for deployment patterns, DLP/encryption options, and how to layer SEG with cloud email security for defense-in-depth.
