Secure Email Gateway vs. Cloud-Native: Which Wins?

The TL;DR

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Keep your Secure Email Gateway (SEG) for spam and known-bad malware filtering before delivery, but pair it with cloud-native, in-tenant detection and post-delivery remediation to stop BEC, account misuse, and internal abuse after delivery. Add Workspace-native controls (Gmail Advanced phishing & malware, Security Sandbox, DMARC, and Context-Aware Access) for layered protection. The real question isn’t “SEG or cloud-native?”—it’s “pre-delivery and post-delivery”. SEGs make a point-in-time decision at the edge and remain excellent at filtering junk and signature-based malware. But the most expensive incidents today are driven by social engineering and credential misuse, which often look clean at the gateway and only become obviously malicious after a user engages (reply-chain fraud, mailbox rule abuse, vendor thread hijack, internal phish). Verizon’s 2025 DBIR again puts the human element around 60% of breaches, which tracks with the kinds of attacks that bypass pure pre-delivery controls. Meanwhile, the stakes are still measured in millions: IBM’s 2025 report shows the global average cost of a breach remains substantial, and the FBI’s IC3 tallied a record $16.6B in cybercrime losses for 2024, with BEC consistently among the costliest categories. Faster detection and containment moves real dollars.

Where each approach shines (and struggles)

Secure Email Gateway (SEG).
Strengths: high-volume pre-delivery filtering for spam and known indicators, mature policies, and reputation checks.
Gaps: limited visibility into post-delivery behavior (forwarding rules, internal mail, lateral movement), little context across apps (email ↔ Drive), and no tenant-native ability to pull messages or reverse changes once delivered.

Cloud-native / ICES (in-tenant).
Strengths: sees what happens inside Workspace, correlates identity + behavior + content, and can remediate after delivery (pull messages, kill malicious forwarders, tighten file shares triggered by email workflows).
Gaps: relies on robust API access and tuned detections; best when paired with strong pre-delivery filtering to keep commodity noise down.

What to enable in Google Workspace (so both sides work together)

Start with the controls you already own:

• Gmail → Advanced phishing & malware protection. Turn it on and scope stricter settings to high-risk org units (Finance, HR, AP). This reduces commodity noise and flags suspicious patterns early.
  
  
• Gmail → Security Sandbox. Detonates risky attachments in isolation before users interact with them. Enable for targeted OUs first if you’re cautious.
  
  
• DMARC. Publish a DMARC policy and move from p=none to quarantine and ultimately reject as you gain confidence from aggregate reports. This blunts spoofing and aligns with supplier-fraud prevention.
  
  
• Context-Aware Access (CAA). Limit download/print/copy for viewers/commenters on unmanaged or noncompliant devices and tighten access by device posture or location. This turns a successful phish into a smaller incident.
  
  

With that foundation, add a cloud-native, in-tenant layer that watches for post-delivery signals (VIP/payment lures, unusual reply-to behavior, suspicious mailbox rules, impossible-travel logins) and auto-remediates: pull delivered messages, disable forwarders, and fix risky Drive shares created via email workflows. 

Decision framework for 2025 (practical, not dogmatic)

Ask three questions:

1. What’s your top loss scenario? If it’s still spam and known-bad malware, a tuned SEG + Gmail native controls might be enough. If it’s BEC/vendor fraud or internal misuse, you need post-delivery detection and remediation in-tenant.
   
   
2. Where does your team spend time? If analysts chase inbox reports and manual pulls, moving those actions into an automated, tenant-native workflow returns hours per week and shrinks mean time to remediate (MTTR).
   
   
3. Can you show outcomes? Track time-to-pull, malicious forwarders neutralized, Drive exposures closed, and wire attempts prevented. Tie improvements to IBM/IC3 benchmarks to communicate impact in dollars.

What “good” looks like in production

A healthy posture in 2025 keeps the SEG to block the obvious and lowers the noise floor for analysts. Inside Workspace, cloud-native controls watch behavior as it unfolds and fix issues automatically—not just alert. Security reviews focus on tuning policies and exceptions, not chasing tickets. Users still move quickly, but dangerous actions face just-in-time friction (sandboxing, DLP warnings, CAA restrictions), and the riskiest flows auto-roll back without a helpdesk thread.

Connect with Material Security

If you’re keeping your SEG, Material Security adds the cloud-native, post-delivery layer you’re missing. Inside Google Workspace, Material correlates identity, content, and behavior to catch BEC and account misuse; then it remediates automatically by pulling messages, disabling malicious forwarding rules, and tightening risky Drive shares that started from email workflows. The outcome is fewer false positives, faster MTTR, and clearer evidence that risk—and cost exposure—are going down. See Material Security in action today.

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