Systems Administrator - Platform Migration & Merge Specialist

Key Responsibilities

• Migration Delivery
• Take ownership of in-flight and upcoming platform migrations, including both Microsoft 365 to Microsoft 365 (tenant consolidation) and Google Workspace Enterprise to Microsoft 365 transitions.
• Design and execute migration approaches for mail, calendars, contacts, files, chat and identity, using the Microsoft Migration Toolset (Exchange Online migration, SharePoint and OneDrive migration tooling) and complementary third-party tooling where appropriate.
• Manage coexistence periods where dual systems operate in parallel, including mail flow configuration, calendar interop, free/busy visibility, and delta synchronisation.
• Plan and execute cutover activities including domain MX changes, primary SMTP swaps, UPN transitions, and the controlled retirement of source environments.
• Write and maintain PowerShell scripts that interact with Exchange Online, Microsoft Graph, Entra ID and SharePoint for bulk operations, validation, reporting and automation.
• Discovery and Analysis
• Develop a thorough understanding of source environments before migration, including users, groups, mail, files, shared drives, calendar resources, chat, third-party integrations and operational workflows.
• Use Google Admin tools, GAM, Microsoft Graph, PowerShell, Microsoft Migration Manager and other appropriate tooling to query, analyse and report on source data.
• Identify migration risks, edge cases and dependencies, including shared mailboxes, delegations, calendar resource booking, SaaS authentication dependencies, and cross-document references such as Google Sheets IMPORTRANGE.
• Document findings and recommend approaches to address them.
• Identity, Licensing and Coexistence
• Plan and implement identity strategies that accommodate Entra ID, Google federation and the broader SaaS application landscape during transitions.
• Manage licensing transitions across Microsoft 365 and Google Workspace, including Cloud Identity downgrades for retained identity-only accounts.
• Maintain mail flow integrity across domains during coexistence, including accepted domain types, forwarding configurations, primary SMTP and alias management.
• Tenant Decommissioning
• Oversee the controlled decommissioning of source environments after successful migration, covering data retention, identity downgrade, licence release and tenant retirement.
• Coordinate retention of legacy native content as a safety net where required.
• Manage SaaS application transitions from legacy identity providers to Entra ID single sign-on.
• Stakeholder Engagement and Proposal Support
• Provide the technical analysis and detailed planning required by the IT Director and CTO to build migration proposals for leadership approval.
• Communicate progress, risks and decisions through Steering Committee forums.
• Translate technical detail for non-technical audiences in user communications, change management materials and service desk guidance.
• Post-Migration Support
• Provide hypercare support during and after migration cutovers.
• Engage directly with senior stakeholders and VIP users to triage and resolve complex issues.
• Iterate on the support model based on real-world feedback and post-migration metrics.