Migrations are among the most challenging IT projects organizations undertake. Moving email, files, and applications to Microsoft 365 involves technical complexity, business disruption risk, and change management challenges that trip up even experienced teams.
The stakes are high. Botched migrations lose data, disrupt operations, and frustrate employees. They blow budgets and timelines while damaging IT credibility. Successful migrations, conversely, position organizations for improved collaboration, reduced infrastructure costs, and modern capabilities.
This guide covers what Microsoft 365 migrations involve, how to approach them successfully, and when professional migration services make sense.
Types of Microsoft 365 Migrations
Different starting points create different migration challenges:
On-Premises to Cloud Migration
Moving from on-premises Exchange, SharePoint, and file servers to Microsoft 365. This is often the most complex migration type, involving:
- Email migration from Exchange Server to Exchange Online
- SharePoint on-premises to SharePoint Online
- File server content to OneDrive and SharePoint
- Active Directory to Azure AD (hybrid or full migration)
- Application migrations or replacements
On-premises migrations also involve decommissioning legacy infrastructure—servers, storage, and associated maintenance—creating ongoing cost savings that help justify migration investment.
Google Workspace to Microsoft 365
Organizations standardized on Google Workspace sometimes migrate to Microsoft 365 for enterprise features, Office application requirements, or strategic platform consolidation. This involves:
- Gmail to Exchange Online
- Google Drive to OneDrive and SharePoint
- Google Docs/Sheets/Slides to Microsoft formats (with conversion considerations)
- Google Calendar to Outlook calendars
- Google Sites to SharePoint (often requiring rebuild rather than direct migration)
Google migrations require careful attention to format conversion. While documents generally convert well, complex formatting, scripts, and add-ons may not translate directly.
Tenant-to-Tenant Migration
Mergers, acquisitions, divestitures, and organizational restructuring sometimes require moving users and content between Microsoft 365 tenants. This involves:
- Mailbox migration between tenants
- OneDrive and SharePoint content migration
- Teams migration (often the most complex aspect)
- Identity and licensing transitions
- Domain transfers
Tenant migrations are technically demanding because Microsoft 365 isn’t designed for easy tenant-to-tenant movement. Specialized tools and careful planning are essential.
Legacy SharePoint Migration
Moving from SharePoint 2013, 2016, or 2019 on-premises to SharePoint Online. Beyond content migration, this often requires:
- Updating customizations for modern SharePoint
- Replacing deprecated features (workflows, InfoPath forms)
- Modernizing classic sites and pages
- Restructuring information architecture for modern patterns
Legacy SharePoint migrations are opportunities to clean up years of accumulated content and improve organization rather than just lifting and shifting problems to the cloud.
Migration Planning Steps
Successful migrations follow a disciplined planning process:
Discovery and Assessment
Understand what you’re migrating:
- Inventory current state. What mailboxes exist? How large are they? What SharePoint sites, libraries, and content volumes? What file server content?
- Assess content. What’s actively used versus dormant? What can be archived or deleted? What has compliance or retention requirements?
- Identify dependencies. What applications integrate with current systems? What workflows and automations exist? What will break when the source system changes?
- Document customizations. Custom SharePoint solutions, Exchange rules and policies, integrations with other systems—all need consideration.
- Evaluate user readiness. How sophisticated are users with current tools? What training needs exist for Microsoft 365?
Planning and Design
Design the target environment and migration approach:
- Define target architecture. How will SharePoint sites be structured? What OneDrive policies apply? How will Teams be organized?
- Plan identity approach. Hybrid identity with directory synchronization? Cloud-only? Federation?
- Determine migration method. Cutover, staged, or hybrid migration for Exchange? Third-party tools or native approaches for SharePoint and files?
- Create migration schedule. What order do groups migrate? What timing minimizes disruption? How long is the coexistence period?
- Plan communications. How will users learn about migration? What training is provided? How are issues reported and addressed?
- Define success criteria. What indicates successful migration? How will you verify completeness and correctness?
Preparation
Get ready for migration execution:
- Clean up source content. Delete obsolete content, archive inactive data, consolidate duplicates. Migrating less content reduces time, cost, and complexity.
- Configure target environment. Set up Microsoft 365 tenant, configure policies, establish site structures, prepare identity synchronization.
- Provision migration tools. Select and configure migration tools, establish connectivity, run test migrations.
- Prepare users. Communicate timelines, provide training resources, set expectations for transition period.
- Test migration process. Pilot migration with limited scope to validate approach and identify issues.
Execution
Perform the actual migration:
- Follow the plan. Execute migration batches according to schedule.
- Monitor progress. Track migration status, error rates, and performance.
- Address issues. Resolve errors promptly. Some issues require immediate attention; others can be addressed post-migration.
- Communicate status. Keep stakeholders informed of progress and any changes to timeline.
- Validate results. Verify content arrived correctly, permissions are appropriate, and functionality works as expected.
Post-Migration
Complete the transition:
- User support. Provide intensive support during initial adoption. Users will have questions and encounter issues.
- Issue resolution. Address migration errors, missing content, and permission problems.
- Decommissioning. Retire source systems according to plan, maintaining backups appropriate to retention requirements.
- Optimization. Tune the new environment based on actual usage patterns.
- Documentation. Update procedures, training materials, and support documentation for the new environment.
Common Migration Challenges
Data Volume and Time
Large environments take time to migrate. Terabytes of SharePoint content or thousands of mailboxes don’t move instantly. Plan for migration windows, potentially running over weekends or extended periods. Incremental approaches that migrate most data before cutover reduce final migration time.
Permissions and Access
Permissions often don’t translate cleanly between systems. On-premises Active Directory groups may not exist in Azure AD. Google Drive sharing doesn’t map directly to SharePoint permissions. Plan permission mapping carefully and validate access after migration.
Custom Solutions and Integrations
Custom SharePoint solutions, Exchange transport rules, workflow automations, and integrations with other systems all need attention. Some can be migrated or converted; others must be rebuilt; some may require alternative approaches in Microsoft 365.
User Adoption and Change Management
Technical migration is only half the challenge. Users comfortable with current tools need help transitioning to new ones. Training, communication, and support during the transition period significantly impact adoption success.
Coexistence Complexity
During migration, some users are on the old system while others are on Microsoft 365. Email must flow correctly. Calendar sharing must work. Document collaboration must function. Coexistence configuration is technically demanding and often underestimated.
Compliance and Retention
Content subject to legal holds, retention policies, or compliance requirements needs careful handling. Ensure migration preserves compliance metadata, maintains required retention, and doesn’t disrupt pending legal matters.
When to Hire Migration Specialists
Some organizations handle Microsoft 365 migrations internally. Others benefit from professional migration services:
Consider hiring specialists when:
- Your team lacks migration experience
- The migration involves complex source systems or large data volumes
- Business disruption risk is significant
- Timeline pressure doesn’t allow for learning curves
- Compliance requirements demand documented, validated processes
- You want to transfer knowledge to internal staff through the engagement
Migration specialists provide:
- Experience from dozens or hundreds of migrations
- Knowledge of common pitfalls and how to avoid them
- Specialized tools and established processes
- Capacity that internal teams may lack
- Objective assessment of risks and realistic timelines
Evaluating migration service providers:
- Request references from similar migrations (similar source systems, similar scale)
- Understand who specifically will work on your project
- Clarify tool licensing—do they include tools, or must you license them separately?
- Review their methodology and project management approach
- Understand post-migration support and issue resolution commitments
- Get clear scope definitions and change management processes
Migration Tools
Various tools support Microsoft 365 migrations:
Microsoft native tools include the Exchange migration dashboard, SharePoint Migration Tool (SPMT), and Migration Manager. These handle straightforward scenarios at no additional cost but may lack features for complex migrations.
Third-party migration tools from vendors like BitTitan, AvePoint, ShareGate, and Quest provide enhanced capabilities: faster throughput, better reporting, more complex mapping options, and features for challenging scenarios. Licensing adds cost but may reduce project duration and risk.
PowerShell and APIs enable custom migration scripting for specific needs. This requires technical expertise but offers maximum flexibility.
Tool selection depends on source systems, migration complexity, budget, and available expertise. Many migration projects use combinations—native tools for straightforward content, specialized tools for complex scenarios.
Planning for Success
Several factors correlate with migration success:
Executive sponsorship. Migration projects touch everyone. Leadership support ensures resources, enforces participation, and signals organizational commitment.
Realistic timelines. Rushed migrations generate errors and frustrations. Allow adequate time for planning, testing, execution, and stabilization.
Thorough testing. Pilot migrations reveal problems before they affect the entire organization. Test with realistic content, real users, and actual workflows.
Communication. Users who understand what’s happening, why, and what to expect handle transitions better than those surprised by changes.
Training investment. Microsoft 365 capabilities differ from legacy tools. Training ensures users can work effectively in the new environment.
Contingency planning. What happens if migration encounters serious problems? Rollback plans, extended coexistence options, and escalation paths provide safety nets.
Post-migration support. Budget resources for intensive support during the weeks following migration. Issues will arise; responsive support minimizes productivity impact.
Organizations that invest appropriately in planning, preparation, and support achieve migrations that improve operations. Those that shortcut the process often struggle with extended disruption and user frustration.
For organizations already on Microsoft 365 looking to improve their SharePoint implementation, modern intranet best practices provide guidance for building effective collaboration environments on the platform.
Planning a Microsoft 365 migration? Let’s discuss how to approach your migration for success.