Why one European manufacturer replaced Trend Micro’s secure email gateway with Proofpoint 

Key takeaways 

• During a technology stack review, the biggest surprise was that employees were emailing sensitive documents to personal accounts.  
• They also discovered their legacy email protection served as a facade, showing its detections as complete while missing hundreds of threats each day. 
• The Proofpoint proof of concept turned a product test into a live shield. 

It started quietly. A few phishing emails here. A suspicious link there. Then one inbox cleanup after another. For a European manufacturer that was running Microsoft 365 with Trend Micro’s secure email gateway (SEG), those small incidents added up. They had a growing sense that attackers were moving faster than their defenses.  

The security team was spending too much time reacting. Administrators questioned why emails that were clearly malicious were reaching inboxes at all. And leadership started to wonder if their email security stack—which was once considered “good enough”—was still fit for today’s threat landscape.  

They hadn’t gone looking to replace Trend Micro. But reality forced the conversation. 

When layered security still isn’t enough 

Like many organizations, this manufacturer had taken what felt like a prudent approach. They used third-party secure email gateway (SEG) from Trend Micro and positioned it in front of Microsoft 365 as the primary line of defense. 

On paper, that should have provided strong coverage. However, attackers don’t read architecture diagrams. Modern phishing campaigns rarely rely on simple malware attachments anymore. Instead, they use: 

• Carefully written social engineering lures 
• Links that become malicious after delivery 
• HTML files that redirect to credential-harvesting sites 
• Supplier impersonation and invoice fraud 
• “No-payload” business email compromise (BEC) 

These techniques can slip past controls that focus too heavily on reputation or static indicators. This leaves defenders to play catch-up once a user has already clicked. And that’s exactly what the security team was seeing. They were doing too much cleanup and not enough prevention.  

The mandate: modernize without disrupting Microsoft 365 

When the company decided to evaluate alternatives, the criteria were practical and focused. Their experience with Trend Micro had already started to reshape how they thought about email security architecture. If Microsoft 365 was becoming the center of user productivity—and attackers were increasingly operating inside that environment—then relying on a perimeter gateway alone no longer felt sufficient. 

They weren’t interested in a multi-month mail-flow redesign. They didn’t want to risk downtime by rerouting all inbound email. And they didn’t want to deploy something heavyweight that created more alerts than answers. 

What they did want: 

• API-based protection behind Microsoft 365. A way to strengthen security inside the cloud platform where users actually worked—without changing MX records—while closing the gaps they were seeing with Trend Micro 
• Demonstrably higher detection. Not marketing claims, but real-world proof—during a live evaluation—that threats Trend Micro missed would actually be stopped 
• Operational simplicity. The ability to release low-risk emails safely, tune policies quickly, and reduce manual triage for an already-lean security team 
• Visibility beyond inbound threats. Insight into risky user behavior and potential data exposure—not just malware 

Those priorities reflect a broader market shift. Rather than perimeter filtering, analyst research increasingly emphasizes email security platforms that combine detection, post-delivery response, and outbound data protection. 

With those goals in mind, the team launched a proof-of-concept (POC) with Proofpoint Core Email Protection API and Adaptive Email DLP. 

The email threats that stopped being theoretical 

Most POCs run quietly in the background. This one didn’t. Almost immediately, administrators began spotting dangerous emails that had made it past Trend Micro—messages that Proofpoint flagged and helped block during the evaluation. 

Instead of waiting until the end of the test period to write a report, the security team started using Proofpoint operationally: 

• Investigating suspicious messages 
• Blocking threats that had already been delivered 
• Removing risky emails from mailboxes 
• Tuning policies in real time 

In effect, the POC became a live shield. That moment matters, because it is exactly what prospects hope for when they test a new security platform. They don’t just want dashboards and metrics; they want to see fewer incidents tomorrow than they had yesterday. 

A second discovery: the email exfiltration risk they couldn’t unsee  

Inbound threats weren’t the only revelation. During the same POC, the team deployed Adaptive Email DLP to better understand outbound activity. What they found surprised them. 

Employees were sending documents to personal email accounts—behavior the company considered undesirable and potentially risky. It wasn’t necessarily malicious. But it was the kind of slow-drip exposure that creates compliance problems, intellectual-property leakage, or regulatory headaches down the road. 

Before Proofpoint, that activity largely flew under the radar. Now it was visible. That insight changed the conversation internally. Email security wasn’t just about stopping attackers anymore. It was about protecting sensitive information and reshaping user behavior. 

Why Trend Micro couldn’t keep pace 

From the customer’s perspective, the contrast was hard to ignore. Their Trend Micro deployment simply didn’t stop enough threats. Cleanup remained manual. Investigations were reactive. That experience mirrors what many organizations encounter when attackers shift tactics faster than their tools evolve. 

User reviews across peer-review platforms frequently highlight that buyers evaluate vendors not only on detection, but on ease of use, automation, and visibility. All of these areas are where teams often feel pain first when tools fall short. 

For this European manufacturer, the verdict was practical rather than academic. Proofpoint was stopping things Trend Micro wasn’t—without creating operational chaos. 

Why the “easy switch” mattered so much 

One of the biggest psychological barriers to changing email security isn’t budget; it’s fear. 

Fear of mail flow disruption. Fear of migration complexity. Fear of weeks spent troubleshooting after go-live. That’s why the company’s insistence on an API-first approach was so important. 

Proofpoint’s deployment model allowed them to strengthen protection behind Microsoft 365 and begin seeing results quickly. They didn’t need to rip out existing infrastructure or reroute inbound traffic during the evaluation. 

For organizations reading this who are stuck on an incumbent SEG because change feels risky, that detail is crucial. Modernization doesn’t have to mean upheaval. Sometimes it means adding smarter detection and response exactly where attackers are already operating—inside the cloud email platform that your business depends on. 

Turning a technical win into a business decision 

By the time the POC concluded, the outcome was clear. Proofpoint had: 

• Detected threats the Trend Micro missed 
• Reduced reactive investigation 
• Delivered visibility into risky outbound behavior 
• Proved easy to deploy and manage 
• Earned trust from the administrators that used it daily 

What began as a technical evaluation quickly became a strategic decision. The company chose to replace Trend Micro with Proofpoint, moving forward with a platform they were confident could keep pace with the modern threat landscape. 

What Trend Micro customers should ask themselves 

If you’re currently running Trend Micro—or using any legacy secure email gateway—ask yourself: 

• Are suspicious emails still reaching inboxes? 
• Are your teams spending more time cleaning up than preventing threats? 
• Do you have visibility into risky outbound behavior? 
• Would deploying something new require a disruptive mail-flow project? 
• Have you actually tested whether another platform performs better in your environment? 

For this European manufacturer, answering those questions honestly is what triggered change. 

Email security has moved on 

Attackers evolve quickly. Email security strategies have to evolve faster. Tools that are designed for yesterday’s malware-centric threats struggle when they’re faced with subtle impersonation, delayed-detonation URLs, and socially engineered fraud.  

Organizations increasingly want platforms that combine advanced detection, post-delivery response, outbound risk controls, and operational efficiency—all inside the Microsoft 365 environment they already run. That’s the future this manufacturer chose. 

Ready to challenge your current solution? 

If you’re relying on Trend Micro or another legacy SEG and wondering whether you’re missing threats—or whether switching would be too disruptive—it may be time to test those assumptions. 

Talk to Proofpoint about running a Core Email Protection API proof-of-concept behind Microsoft 365. See how modern, API-based email protection performs in your environment.  

Learn more about enhancing Microsoft 365 security, download our e-book: More 

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