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Cloud·18 Déc 202510 min
Migrating Your Mailboxes to Microsoft 365 Without Cutting Off Email During the Switch
By Helion Cloud Team
Plan your Exchange on-premise to Microsoft 365 migration. Key steps, pitfalls to avoid and best practices for a transition without service interruption.
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Migrating from on-premise Exchange to Microsoft 365 is a structuring project that requires rigorous planning. This guide walks you through every step to ensure a successful transition without service interruption.
01
Preliminary audit and inventory
Start with a complete inventory: number of mailboxes, data size, transport rules, existing connectors. Identify third-party applications connected to Exchange. This audit determines the migration strategy choice.
02
Choosing the migration strategy
Hybrid migration for extended coexistence, cutover migration for small organizations, staged migration for complex environments. Each approach has its advantages. Helion Cloud recommends the strategy suited to your context.
03
Preparation and testing
Configure Azure AD Connect for identity synchronization. Prepare DNS records. Test with a pilot group. Validate transport rules and signatures. Only migrate en masse after validating all scenarios.
04
Migration and training
Plan migration outside business hours. Communicate clearly with users. Provide enhanced support for the first days. Train teams on differences between on-premise Outlook and Outlook 365.
Summary
A successful Exchange migration requires expertise and planning. Helion Cloud has migrated hundreds of companies to Microsoft 365 and guarantees a smooth transition for your organization.
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