Senior Messaging & Core Infrastructure Engineer (Exchange and Messaging Specialist)

We are seeking a highly experienced Senior Systems Engineer with deep expertise in Microsoft Exchange and Enterprise Messaging, to join our Global Core Systems Infrastructure team in London or Geneva.

The role focuses primarily on the support, operation, design, and evolution of on-premises Exchange, while also covering the design and assessment of Exchange Online, hybrid messaging, and broader core infrastructure services. You will be critical in ensuring the availability, security, and performance of business-critical messaging systems, while contributing to the platform’s long-term strategy and potential cloud transformation.

Key Responsibilities

Messaging (Primary Focus)

• With a global team, own and manage Microsoft Exchange (on-premises) as a core business-critical service. Supporting messaging and all related services
• Administer and support Exchange Online and hybrid configurations, including mail flow, transport, and coexistence
• Manage mailbox lifecycle, migrations, archiving, and retention policies
• Design and maintain secure mail flow, including anti-spam, anti-phishing, and encryption controls
• Troubleshoot complex messaging, transport, and client connectivity issues
• Lead or contribute to Exchange modernisation and migration initiatives

Core Infrastructure (Secondary Scope)

• Support Active Directory and Entra ID (Azure AD), including hybrid identity and authentication
• Administer Windows Server environments including DNS, DHCP, ADFS, Certificate Services
• Manage and maintain VMware virtualisation platforms, including performance, capacity, and lifecycle
• Support Microsoft 365 services including those related to messaging and collaboration
• Contribute to high availability, backup, and disaster recovery designs

Platform & Operations

• Ensure availability, performance, and resilience of messaging and core infrastructure
• Apply security best practices aligned with enterprise and regulatory requirements
• Participate in incident management and complex troubleshooting across infrastructure domains
• Maintain clear documentation, operational procedures, and system designs
• Support audits, compliance, and risk assessments
• Collaborate with global teams and stakeholders across regions

Leadership & Engineering Contribution

• Act as a subject matter expert (SME) for Exchange and messaging services
• Provide technical leadership and mentoring to other engineers
• Contribute to architecture, design decisions, and strategic roadmap planning
• Drive improvements in automation, monitoring, and operational efficiency

Essential

• Strong hands-on experience with Microsoft Exchange Server (on-premises), Exchange Online, and hybrid environments
• Enterprise messaging architecture and mail flow design, including transport rules, connectors, and message hygiene
• Mailbox migrations and coexistence strategies
• Messaging security (anti-spam, anti-phishing, encryption)
• Experience with PowerShell and automation

Broader Infrastructure

• Solid experience with Active Directory, Entra ID (Azure AD), Microsoft 365, and Windows Server administration
• Good working knowledge of VMware / vSphere infrastructure
• Understanding of identity, authentication, and security principles
• Familiarity with backup, DR, and monitoring platforms

Desirable

• Experience leading Exchange → Exchange Online migrations
• Exposure to large-scale, globally distributed environments
• Knowledge of mobile/messaging integration (e.g. Intune / mobile clients)
• Microsoft / M365 / VMware certifications

Soft Skills

• Reliable and structured, able to operate critical systems with ownership
• Strong problem-solver with a methodical troubleshooting approach
• Clear communicator across technical and business stakeholders
• Comfortable working in a global, fast-paced environment
• Team player with a professional, service-oriented mindset