a23 is an Australian owned Systems Integrator headquartered in Canberra. We provide specialist ICT services across diverse technologies and are recognised as a valued strategic partner for Government and private sector organisations. a23 has grown to become a prominent strategic partner, focused on servicing the needs of small to medium-sized agencies to deliver quality outcomes through expert people, great relationships, and fit-for-purpose technologies.

Why work for a23?

a23 is a well-established Australian technology company experiencing strong growth, fuelled by rising demand for our expertise in Cyber Security, Networking, Cloud, Data and AI, and Hybrid Cloud. We bring the agility and innovation of a start-up backed by the maturity, credibility, and delivery assurance of an established market leader.

Our teams deliver secure, scalable solution to government and enterprise client, blending deep technical capability with a client-first culture. Whether enabling AI-driven insights, transforming hybrid infrastructure, or securing mission-critical environments, a23 is trusted to deliver at a national scale.

We offer a collaborative and flexible working environment alongside a range of employee advantages such as an annual wellbeing allowance. For more information, seeOur Careers - A23.

About a23

a23 is an Australian owned Systems Integrator headquartered in Canberra. We provide specialist ICT services across diverse technologies and are recognised as a valued strategic partner for Government and private sector organisations. a23 has grown to become a prominent strategic partner, focused on servicing the needs of small to medium-sized agencies to deliver quality outcomes through expert people, great relationships,



and fit-for-purpose technologies.

Why work for a23?

a23 is a well-established Australian technology company experiencing strong growth, fuelled by rising demand for our expertise in Cyber Security, Networking, Cloud, Data and AI, and Hybrid Cloud. We bring the agility and innovation of a start-up backed by the maturity, credibility, and delivery assurance of an established market leader.

Our teams deliver secure, scalable solution to government and enterprise client, blending deep technical capability with a client-first culture. Whether enabling AI-driven insights, transforming hybrid infrastructure, or securing mission-critical environments, a23 is trusted to deliver at a national scale.

We offer a collaborative and flexible working environment alongside a range of employee benefits such as an annual wellbeing allowance. For more information, seeOur Careers - A23.

Job Description

The Role

a23 is seeking a Senior Microsoft 365 Exchange Engineer. This full time contract position reports to the Practice Lead – Modern Workplace and allocated to one of our valued customers. This role is part of the team supporting the secure, reliable and effective operation of Microsoft Exchange environments across on-premises, hybrid and Microsoft 365 cloud platforms.

If you enjoy taking ownership of complex messaging issues,



leading Exchange migrations and delivering secure, reliable outcomes for customers, you will enjoy a23.

This role operates in a hybrid arrangement, with attendance at customer sites and the a23 office as required. You will use your Microsoft Exchange and Microsoft 365 expertise to design, implement, migrate, administer and support enterprise messaging environments.

Role responsibilities

Exchange and messaging

- Design, implement, maintain and support Microsoft Exchange Server and Exchange Online environments.
- Administer and support on-premises, hybrid and Microsoft 365 cloud messaging platforms.
- Configure and manage mail flow, message hygiene, retention and compliance controls.
- Troubleshoot complex email, identity, messaging, performance and availability issues.
- Monitor messaging service health and resolve technical, security and operational risks.

Migration and security

- Lead Exchange migrations, including hybrid and cloud transformation projects.
- Support integrations with Entra ID, Active Directory and related identity services.
- Configure and support email security controls including SPF, DKIM and mail-routing technologies.
- Ensure messaging environments meet security, compliance and operational requirements.

Service delivery

- Develop and maintain solution designs, architecture documentation, operating procedures and as-built documentation.
- Collaborate with infrastructure, identity, security and cloud teams to deliver reliable service outcomes.
- Engage with project managers, executives, technical teams, customers and vendors as required.
- Provide technical leadership, guidance and mentoring to other engineers.

📌 Senior Microsoft 365 Exchange Engineer (Sydney)
🏢 A23
📍 Sydney