Migrate Microsoft Exchange Server to Microsoft 365

In 2014, as part of Eterna Plc’s enterprise IT modernization initiative, I led the migration of their on-premises Microsoft Exchange Server (deployed in 2011) to the cloud-based Microsoft 365 Exchange Online platform. The project included setting up a hybrid environment, deploying Azure Active Directory, and synchronizing all on-prem user accounts and mailboxes to the cloud.

This upgrade enhanced scalability, security, mobile access, and reduced the total cost of ownership for IT infrastructure.

Key Deliverables

Exchange On-Prem to Exchange Online Migration

• Migrated over 1,500 user mailboxes from Microsoft Exchange Server 2013 (on-prem) to Exchange Online (Microsoft 365)

• Used Hybrid Exchange Migration to ensure zero downtime and full data integrity

• Preserved email histories, calendar events, contacts, and folder structures during migration

Azure Active Directory Deployment & Synchronization

• Deployed Azure AD Connect to sync on-prem Active Directory with Azure Active Directory

• Configured password hash sync and single sign-on (SSO) for seamless login experience

• Ensured OU filtering, attribute scoping, and hybrid identity setup

• Created Azure AD Conditional Access Policies for security compliance

Modern Workplace Enablement

• Enabled Outlook Web Access (OWA), mobile mail sync, and OneDrive for Business

• Rolled out Microsoft Teams (early phase) and SharePoint Online as collaboration tools

• Configured multi-factor authentication (MFA) for security-hardening

• Implemented data loss prevention (DLP) rules and retention policies within Microsoft Purview

Security, Backup & Compliance

• Implemented email encryption, anti-spam/anti-malware policies, and SafeLinks

• Integrated Microsoft Defender for Office 365

• Configured email journaling and legal hold for compliance and audit requirements

• Provided backup and archiving strategy via third-party tools.