How to Test Your Email Security Gateway Against Advanced Phishing

Email remains a primary route into Australian organisations, even when cloud platforms, endpoint protection and multi-factor authentication are in place. Modern phishing campaigns use trusted brands, realistic payment requests, compromised accounts and carefully timed messages that can bypass simple spam filters.

A useful security gateway assessment should test the complete defensive chain: message inspection, authentication controls, attachment and link analysis, user reporting, security operations and incident response. The goal is to identify how an organisation would handle a targeted attack without putting staff, customers or production systems at risk.

Define A Controlled Testing Scope

Begin with written authorisation from the organisation’s executives, legal team and security owner. Identify approved domains, mailboxes, test dates, sending infrastructure and escalation contacts. A controlled exercise should never imitate a real supplier, bank or government department in a way that could cause confusion outside the approved group.

Include the technologies that process email before delivery. These may include Microsoft 365 or Google Workspace, secure email gateways, DNS filtering, sandboxing, mail-flow rules and security information and event management platforms. Australian businesses with teams in Sydney, Melbourne, Brisbane or regional locations should account for different working hours, hybrid staff and remote workers with limited access to security support.

Build Realistic Phishing Scenarios

Advanced phishing simulations should reflect the organisation’s risk profile rather than rely on generic “account expired” messages. A financial institution may need a business email compromise scenario involving a payment change, while an online retailer could test fake delivery notices or fraudulent refund requests. Healthcare providers should consider messages that imitate appointment systems, pathology services or medical suppliers.

Use harmless landing pages, non-executable test files and pre-approved domains. Do not collect real passwords or personal information. For a safe assessment, the simulation can record whether a recipient opened the message, followed a link, reported it or requested assistance, while avoiding the capture of credentials or sensitive content.

Attack Paths Worth Simulating

• Spoofed supplier invoices and bank-detail change requests
• QR-code phishing aimed at mobile-first employees
• Cloud account alerts using lookalike Microsoft or Google domains
• Malicious HTML attachments, compressed files and weaponised documents
• Executive impersonation targeting payroll, finance or procurement

Examine Gateway Detection Controls

Review whether the gateway validates SPF, DKIM and DMARC, including enforcement policies and alignment. Test lookalike domains, display-name deception, reply-to manipulation and messages sent from legitimate but compromised accounts. A mature control set should assess sender reputation without treating reputation as the only decision factor.

Link protection should inspect redirects, newly registered domains, URL-shortening services and content that changes after delivery. Attachment controls should detonate suspicious files in a sandbox and identify macros, scripts, password-protected archives and uncommon file types. Test whether the gateway quarantines risky content, rewrites links safely and provides useful explanations to administrators.

Measure Staff And SOC Response

Detection is only one part of email security. Record how quickly the security operations team sees an alert, investigates it, blocks related indicators and searches for similar messages. Check whether a reported email creates a case automatically and whether analysts can trace delivery, clicks and attempted follow-on activity across the environment.

Australian organisations should also test after-hours response. A phishing campaign launched late in the evening may affect staff working from home, travelling between offices or supporting customers across time zones. Clear escalation paths are particularly important for financial services, hospitals and government agencies where a delayed response can create operational and regulatory consequences.

Evidence To Capture During The Exercise

• Delivery, quarantine and rejection decisions for every test message
• Authentication results, gateway verdicts and sandbox findings
• Time from user report to analyst triage and containment
• Click, attachment and reporting rates without collecting credentials
• SIEM alerts, investigation notes and final remediation actions

Protect Privacy And Regulatory Obligations

A phishing exercise must align with the Privacy Act 1988 and the Australian Privacy Principles when personal information is involved. If a simulation exposes or processes employee data, define retention, access and deletion rules in advance. The Notifiable Data Breaches scheme also makes it important to understand whether an actual incident could trigger assessment and notification duties.

The Spam Act 2003 is relevant when sending simulated messages, particularly if external recipients or marketing-style content are involved. Obtain legal advice before testing outside the organisation. For regulated entities, map the exercise to APRA CPS 234, the Australian Signals Directorate’s Essential Eight and relevant contractual obligations. These controls help demonstrate that email security is part of a broader information-security program.

Improve Controls After Testing

Prioritise findings according to business impact, exploitability and the time an attacker could remain undetected. A gateway that blocks obvious malicious files but allows lookalike domains may need stronger DMARC enforcement, better impersonation protection and improved threat intelligence. A low reporting rate may indicate unclear procedures rather than careless employees.

Feed indicators from the exercise into mail-flow rules, endpoint detection, identity protection and SIEM monitoring. Update playbooks for account takeover, invoice fraud and suspected data theft. Security awareness training should focus on practical signals such as urgent payment language, unexpected QR codes, unusual sender addresses and requests to bypass normal approval processes.

Repeat testing after major changes to email platforms, domains, authentication policies or business processes. Infoziant Security can support an authorised VAPT engagement, email gateway review, SIEM validation or broader cloud and infrastructure assessment, with findings mapped to the organisation’s risk and compliance requirements.

Arrange a controlled email security assessment with Infoziant Security to identify bypass routes, validate monitoring and strengthen your response before an advanced phishing campaign reaches real users.