Email Security Engineer - NCS Australia

We are seeking a hands-on Email Security Engineer to support the delivery and operational uplift of Optus email security. The contractor will work closely with Luc and the Director, Data Protection & Email Security, to strengthen outbound controls, complete Mimecast implementation activities and support the controlled decommissioning of Trend Micro email security capabilities.

This is a delivery-focused role for someone who can operate at both engineering and operational levels - designing changes, implementing them, troubleshooting issues, documenting outcomes and handing over stable services to BAU teams.

Key responsibilities

• Execute configuration and engineering changes in a controlled manner.
• Coordinate testing with technical teams and business stakeholders.
• Develop runbooks, technical procedures, support models and knowledge-transfer materials.
• Monitor post-change outcomes and recommend further tuning.
• Escalate issues early and drive actions through to completion.
• Design, implement and validate the Mimecast outbound mail flow.
• Review outbound routing, controls, policies, authentication and delivery behaviour.
• Identify and close gaps across data protection, malware, impersonation, URL and policy enforcement controls.
• Troubleshoot mail-flow issues across Mimecast, Microsoft 365 and downstream or third-party systems.
• Support testing, cutover planning, monitoring and rollback readiness.
• Map current Trend Micro email security capabilities, integrations, dependencies and traffic flows.
• Define the migration and decommissioning sequence in coordination with the Mimecast target state.
• Remove or retire legacy configurations, rules and integrations safely.
• Validate that required protection and mail-flow outcomes remain in place after each change.
• Support defect resolution, rollback planning, evidence capture and final closure of the decommissioning work.
• Strong hands-on experience administering and engineering Email Security.
• Demonstrated experience with outbound email security and enterprise mail-flow troubleshooting.
• Practical experience implementing email journaling and validating message coverage.
• Experience uplifting email security policies and managing controlled exceptions.
• Experience with Microsoft 365 / Exchange Online mail flow, connectors, transport rules and message tracing.
• Experience retiring or migrating legacy email security platforms, preferably Trend Micro.
• Working knowledge of SPF, DKIM, DMARC, SMTP, DNS and email authentication.
• Ability to produce clear technical documentation and operational handover material.