Topic starter
14/07/2026 4:23 pm
TL;DR: A European manufacturer found its legacy email security stack was missing hundreds of threats each day and allowed employees to email sensitive documents to personal accounts, according to Proofpoint. The case shows why email protection now has to combine post-delivery response, outbound data controls, and cloud-native visibility, not just perimeter filtering.
Editorial analysis by NHI Mgmt Group, based on content published by Proofpoint: “Why one European manufacturer replaced Trend Micro’s secure email gateway with Proofpoint”.
Key questions
Q: What breaks when a legacy email gateway is the only line of defence against modern phishing?
A: Legacy gateways tend to fail when phishing is delivered with delayed links, impersonation, or no-payload business email compromise.
Q: Why do Microsoft 365 email environments need post-delivery response and outbound controls?
A: Because the threat is no longer limited to inbound malware.
Q: What are the warning signs that your email security stack is falling behind?
A: The clearest signs are repeated inbox cleanup, suspicious emails reaching users, manual investigation work, and no visibility into outbound sharing of sensitive documents.
Practitioner guidance
- Assess post-delivery response in Microsoft 365 Test whether your current email stack can remove or quarantine malicious messages after they land in user inboxes, not just block them at ingress.
- Validate outbound document controls Review whether email DLP can identify personal-account sharing, sensitive file movement, and policy violations without creating excessive manual triage.
- Measure real phishing detection against your environment Run controlled evaluations with delayed links, impersonation lures, and no-payload BEC messages to see what actually reaches users.
Bottom line: Modern phishing now exploits delivery-time trust, delayed links, and impersonation in ways that perimeter email gateways often miss.
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14/07/2026 5:06 pm
Legacy email gateways are now a coverage gap, not a complete defence. This article shows that perimeter filtering can miss threats that are only revealed after delivery, especially in Microsoft 365 environments. The problem is not that email security failed to exist, but that it was designed around an older threat model. Practitioners should treat cloud mailbox visibility as a core control requirement, not an optional enhancement.
A question worth separating out:
A: Not automatically, but they should challenge any design that depends on perimeter filtering alone. If a gateway cannot see delivered threats, remove risky messages from mailboxes, or govern outbound data movement, it is probably not enough for a Microsoft 365-centric environment. The right decision is based on control coverage, not on whether the tool is already installed.
👉 Read our full editorial: Legacy email gateways miss modern phishing and data exfiltration