The Top 5 Email Attacks Targeting Businesses

Email is still the lifeblood of business communication — and that’s exactly why it remains the most targeted vector for cyberattacks.

Whether it’s phishing, impersonation, or malware delivery, email attacks are evolving faster than most businesses can react. For IT partners, resellers, and security professionals, this creates a critical challenge: how do you stay one step ahead of criminals who thrive on deception, speed, and increasingly, automation?

The answer lies in understanding how these attacks work — and deploying advanced cloud-based email security designed to catch what traditional filters miss.

Let’s break down the five most common email attacks causing havoc in businesses right now, with real-world context from the MailGuard threat blog — and why layering your client's defenses has never been more important.

Phishing has been around for decades, but it’s not going anywhere — because it keeps working. These emails typically impersonate legitimate brands or organisations and trick recipients into clicking a link or sharing credentials.

🧠 Why it works: Attackers exploit trust. Many phishing emails mimic popular platforms — like Microsoft 365, Google, or logistics services — with convincing branding and urgent messaging.

📌 Real-world example: MailGuard intercepted a phishing scam impersonating Xero, the accounting platform, using a fake invoice notification to lure users into entering their credentials on a cloned login page. To the untrained eye, it was nearly identical to a legitimate Xero email.

🛡️ How to stop it: Phishing emails are increasingly dynamic, using rotating domains and fresh tactics. Cloud-based email security with real-time threat intelligence is essential for detecting and stopping these threats before they reach users.

BEC attacks are highly targeted and often difficult to detect. They involve impersonating a senior executive (like a CEO or CFO) or a trusted vendor to trick someone into transferring money or disclosing sensitive information.

🧠 Why it works: BEC doesn’t rely on malicious links — it relies on human psychology. These attacks are social engineering at its most refined.

📌 Real-world example: In one attack intercepted by MailGuard, scammers posed as a company director requesting a wire transfer from the accounts team. There were no attachments, no links — just a simple, persuasive email designed to create urgency and pressure.

🛡️ How to stop it: Because BEC attacks often evade traditional filters, AI & ML-powered anomaly detection and sender authentication (like DMARC, SPF and DKIM validation) are key. Equally important is training users to recognise unusual requests, especially involving payments.

3. Malware & Ransomware Delivery – The Trojan in Your Inbox

Email remains one of the most common delivery methods for malware — including ransomware, spyware, and remote access trojans (RATs). These are often disguised as attachments or links to documents that appear to be invoices, resumes, or shipping notifications.

🧠 Why it works: Users are conditioned to open attachments. When emails appear to come from a supplier, customer, or internal team member, hesitation goes out the window.

📌 Real-world example: MailGuard flagged a malware campaign posing as DHL, tricking users into clicking a “shipping document” which actually downloaded a malicious file. The emails were cleanly branded and appeared to come from a legitimate domain.

🛡️ How to stop it: Malware detection needs to go beyond signature-based scanning. Sophisticated AI & ML-powered threat detection based on decades of real-world intelligence, can identify and block malicious payloads in real time, even if they’re previously unknown.

4. Invoice & Payment Scams – The Vendor Switcheroo

Also known as fake invoice fraud, these scams involve impersonating a supplier or vendor and requesting a change to banking details. They can be incredibly damaging — especially when the attack slips through a conversation with no obvious warning signs.

🧠 Why it works: Attackers take their time. They often monitor email threads, insert themselves into ongoing conversations, and use legitimate-sounding language to appear credible.

📌 Real-world example: In a case shared by MailGuard, attackers impersonated a legitimate supplier and sent a request to update banking details for an upcoming payment. The email used correct formatting and even copied the supplier’s email signature.

🛡️ How to stop it: These attacks are subtle. Cloud-based security tools that analyse sender behaviour, domain age, and message context can help flag suspicious patterns. For high-risk functions like finance, implementing manual verification steps (e.g., phone confirmation) is still critical.

5. Spoofed Brand Attacks – The Familiar Face with a Hidden Motive

Brand impersonation is a growing trend, where attackers spoof well-known companies to build trust instantly. These attacks often use urgent language (“Your account is suspended,” “Payment failed”) to prompt a reaction — and they can be devastating.

🧠 Why it works: Recognition lowers suspicion. If users believe the email is from Telstra, Australia Post, Netflix, or Microsoft, they’re more likely to engage without thinking.

📌 Real-world example: MailGuard recently intercepted an email pretending to be from myGov, claiming the recipient had an outstanding refund. The link led to a fake login page designed to harvest credentials — and even asked for driver licence details.

🛡️ How to stop it: Brand impersonation detection requires deep analysis of email content, layout, domain patterns, and user interaction history. Cloud-based platforms using real-time feeds and AI & ML-powered engines are far more effective than traditional perimeter solutions.

Why Native Security Isn’t Enough

If you’re relying solely on the default protections offered by Microsoft 365 or Google Workspace, these threats can — and do — get through. Native filters aren’t designed to stop fast-evolving, zero zero-day threats. They’re reactive by nature and often depend on known indicators.

Cloud-based email security solutions act as a dedicated layer of defence — filtering out malicious content in real time, often hours ahead of traditional tools.

For IT partners and resellers, this is a clear value proposition:

• Protect your clients with advanced threat detection
• Reduce helpdesk tickets and reactive clean-up
• Offer managed services that drive recurring revenue
• Build trust as a cybersecurity advisor — not just a provider

The Inbox Is the New Frontline

Email remains the easiest way into a business — and the most overlooked. The rise in impersonation, social engineering, and zero zero-day payloads means that traditional defences are no longer enough.

For IT leaders, MSPs, and resellers, the message is clear: it’s time to go beyond the basics and deliver a solution that matches the sophistication of the threat.

Keeping Businesses Safe and Secure

Prevention is always better than a cure, and one of the best defences is to encourage businesses to proactively boost their company’s cyber resilience levels to avoid threats landing in inboxes in the first place. The fact that a staggering 94% of malware attacks are delivered by email, makes email an extremely important vector for businesses to fortify.

No one vendor can stop all email threats, so it’s crucial to remind customers that if they are using Microsoft 365 or Google Workspace, they should also have a third-party email security specialist in place to mitigate their risk. For example, using a specialist third-party cloud email solution like MailGuard.   

For a few dollars per staff member per month, businesses are protected by MailGuard's specialist, zero zero-day email security. Special Ops for when speed matters!  Our real-time zero zero-day, email threat detection amplifies your client’s intelligence, knowledge, security and defence.

MailGuard provides a range of solutions to keep businesses safe, from email filtering to email continuity and archiving solutions. Speak to your clients today to ensure they’re prepared and get in touch with our team to discuss fortifying your client’s cyber resilience.

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