Enterprise-scale migration portfolio: 1.83M+ users migrated across 216+ M&A and tenant consolidation programs. Proprietary minimal-disruption migration tool. Microsoft expertise since 1997.
Microsoft 365 Migration Services (Enterprise-Scale Portfolio) — enterprise Microsoft consulting resource from EPC Group. We provide strategic guidance, implementation expertise, governance frameworks, and compliance-native delivery across the Microsoft ecosystem (Power BI, Microsoft Fabric, Microsoft 365, SharePoint, Azure, AI Governance, Microsoft Copilot).
By Errin O'Connor, Founder & Chief AI Architect, EPC Group
Who is the best Microsoft 365 migration partner? EPC Group has documented one of the largest enterprise Microsoft 365 migration portfolios — 1.83M+ users migrated across 216+ M&A / tenant consolidation programs and hundreds of Google-to-M365 conversions. Our minimal-disruption migration tool ensures a smooth transition. With experience in the Microsoft ecosystem since 1997, we are prepared to meet your needs.
Founded by Errin O'Connor, a 4x bestselling author (Microsoft Press / Sams), EPC Group is one of the oldest Microsoft Gold Partners in North America. We specialize in:
Microsoft 365 migration is not a simple service. The choice of a migration partner can greatly impact your organization. A partner who only moves your email may lead to:
EPC Group has built its reputation on one principle: zero downtime, a documented 5-day cutover average, zero surprises.
For since 1997, EPC Group has managed thousands of enterprise migrations across various scenarios. These include:
Our documented portfolio of Google-to-M365 cloud migrations (across an enterprise migration base of 1.83M+ users total) reflects one of the largest completed-conversion programs among Microsoft partners.
EPC Group stands out due to our proprietary migration tool, which has been refined over 15 years. Unlike standard products such as ShareGate, BitTitan MigrationWiz, or native Microsoft migration tools, our platform offers:
EPC Group uses a 6-phase migration methodology and dedicated project teams. Fixed-fee engagements are scoped against your actual workload inventory rather than time-and-materials open-ended discovery, which compresses the discovery-to-cutover window versus starting from a blank plan.
Every migration is executed with documented data-fidelity checklists and per-item source-vs-destination reconciliation before cutover signoff.
Few Microsoft partners match this combination of experience, proprietary technology, and regulated-industry expertise.
EPC Group is one of the oldest Microsoft Gold Partners in North America. Founded by Errin O'Connor, a 4x bestselling author (Microsoft Press / Sams) whose books on Power BI and SharePoint. This depth of Microsoft ecosystem knowledge means we understand not just how to move data, but how to architect the target environment for optimal performance, security, and adoption.
Our migration tool was built from the ground up over 15 years. It delivers 50-100 GB/hour throughput with parallel batch processing, checksum validation for every item, and automatic retry for throttled API calls. Unlike third-party tools that hit Microsoft API limits, our tool is optimized for sustained high-volume transfers. The result: migrations completed 40-60% faster with a 5-day average cutover.
This Google Workspace to Microsoft 365 migration base ranks among the largest documented in the industry. Each migration taught us something new about edge cases: Google Vault archives, shared drives with complex permissions, Google Groups to Microsoft 365 Groups conversion, and the dozens of gotchas that only surface at enterprise scale. This institutional knowledge is baked into our migration runbooks.
Private equity firms and corporate development teams choose EPC Group because M&A timelines are immovable. When a deal closes on a specific date, the acquired company's employees need Day-1 access to corporate systems. We provide due diligence assessments, Day-1 readiness plans, and accelerated tenant consolidations that meet deal timelines every time.
Healthcare, financial services, government, and education organizations cannot afford compliance gaps during migration. EPC Group maintains compliance continuity throughout the migration process with BAA-compliant handling for HIPAA, SOC 2 chain-of-custody documentation, FedRAMP-aligned consulting expertise procedures for government environments, and FERPA-compliant student data migration.
Every migration gets a dedicated team: project manager, lead migration engineer, identity architect, SharePoint specialist, and 24/7 support during cutover windows. Our team members average 15+ years of Microsoft migration experience. You work with the same team from discovery through hypercare, not a revolving door of junior consultants.
Every migration scenario. Every source platform. Every industry. One partner with the track record to prove it.
Merge or split Microsoft 365 tenants during mergers, acquisitions, and divestitures. Day-1 IT integration with zero business disruption.
Enterprise Google-to-M365 migration portfolio — Gmail, Drive, Calendar, Contacts, Sites, and Chat migrated with full metadata preservation.
On-premises Exchange 2010-2019 to Exchange Online. Hybrid coexistence with staged mailbox moves and zero mail flow interruption.
Network file shares and mapped drives to SharePoint Online and OneDrive. Permissions mapping and metadata preservation.
Full on-premises infrastructure migration to Microsoft 365 cloud. Active Directory, Exchange, SharePoint, and file servers.
Organizations with multiple M365 tenants acquired over time. Consolidate into a single tenant for unified management.
Developed over 15 years. Used in 2,000+ migrations. Documented data-fidelity verification at cutover. The technology advantage behind EPC Group's enterprise migration reliability.
Continuous coexistence means users never experience a gap in service. Email flows, files sync, and calendars update throughout the entire migration.
Parallel batch processing with optimized API utilization delivers sustained throughput that exceeds any third-party migration tool on the market.
Every item transferred is validated with checksum comparison. If a file, email, or calendar event does not match perfectly, it is automatically re-migrated.
Every action is logged with timestamps, user context, and data classification. Logs serve as audit evidence for HIPAA, SOC 2, FedRAMP, and internal compliance teams.
Microsoft API throttling is handled automatically with exponential backoff. No failed items, no manual intervention, no data gaps from rate limiting.
File timestamps, version history, sharing permissions, folder structures, and custom metadata are preserved exactly as they were in the source environment.
Project managers and stakeholders monitor migration progress, error rates, and completion estimates through a live dashboard with email alerts.
Migrates from Google Workspace, Exchange on-premises, Lotus Notes, Novell GroupWise, Zimbra, and any IMAP-compatible email system to Microsoft 365.
| Capability | EPC Group Tool | ShareGate | BitTitan | Native Microsoft |
|---|---|---|---|---|
| Throughput (GB/hour) | 50-100 | 10-25 | 15-30 | 5-15 |
| Zero-downtime coexistence | Yes | Partial | Yes | Limited |
| Checksum validation | Every item | No | No | No |
| Compliance audit logging | Full | Basic | Basic | Minimal |
| Cross-platform (Google, Notes) | Yes | SharePoint only | Yes | Limited |
| Auto-retry with backoff | Yes | Yes | Yes | Manual |
| Real-time dashboard | Yes | Yes | Yes | PowerShell logs |
| Metadata preservation | Full | Partial | Partial | Partial |
Proven across 2,000+ migrations. Every phase has defined deliverables, exit criteria, and rollback procedures. No shortcuts, no surprises.
Every organization is different. Here is what to expect based on your user count and data volume.
Single-batch migration with weekend cutover. Email, files, and calendar migrated in one pass. Minimal coexistence period. Best for small businesses moving to M365 for the first time.
Two-batch migration: pilot group (50 users) followed by remaining users. Coexistence period for email routing. SharePoint site migration with permissions mapping. Department-level training.
Multi-batch migration across 3-4 waves. Full coexistence with mail flow rules. SharePoint information architecture redesign. Teams migration with channel mapping. Change management program.
Enterprise phased migration with dedicated project team. Complex identity architecture. Multi-region considerations. Custom application migration. Executive sponsorship and communication program. Compliance validation per phase.
Full enterprise transformation. Multiple workstreams running in parallel. Regional migration waves across time zones. Custom migration tool deployment. 24/7 war room during cutover. Post-migration optimization and adoption program.
Deal-timeline-driven. Due diligence assessment during LOI phase. Day-1 readiness plan for closing. Accelerated tenant merge with identity federation. Compliance continuity documentation for regulators. Fixed-fee pricing for budget certainty.
Regulated industries require more than data movement. They require compliance continuity, audit trails, and validated controls throughout the entire migration lifecycle.
Fixed-fee pricing with no surprises. Every proposal includes a detailed scope, timeline, and deliverables. All prices are determined after a discovery assessment.
All pricing is indicative. Final proposals are based on a discovery assessment of your specific environment and requirements. Contact us for a custom quote.
Real results from real enterprise migrations. Every case study represents a completed engagement with verified outcomes.
Zero downtime, HIPAA compliant, completed 3 weeks ahead of schedule
100% data integrity, SOC 2 maintained throughout, $2.1M annual savings
FedRAMP-aligned consulting expertise, zero security incidents, full audit trail
6 tenants merged, $4.2M license savings, unified management
FERPA compliant, 99.8% user satisfaction, Copilot enabled
Clean separation on Day 1 of divestiture closing, zero data leakage
When deal timelines are immovable and integration success determines transaction value, private equity firms and corporate development teams turn to EPC Group.
During the letter of intent (LOI) phase, EPC Group assesses the target company's Microsoft 365 environment to identify migration risks, hidden costs, and integration complexity. Our assessment report gives deal teams the IT cost projections they need for financial modeling. We have uncovered licensing liabilities, security gaps, and compliance deficiencies that directly impacted deal valuations.
On the day a deal closes, acquired employees need access to the acquiring company's email, Teams, SharePoint, and corporate applications. EPC Group builds Day-1 readiness plans that include identity federation between tenants, temporary mail flow rules, emergency access to critical applications, and communication templates. Day-1 failures create employee anxiety and productivity loss that set the tone for the entire integration.
M&A deals often have integration milestones tied to earnout provisions or regulatory requirements. EPC Group's proprietary migration tool and dedicated project teams complete tenant consolidations 40-60% faster than standard timelines. For a recent PE roll-up, we consolidated 6 tenants (15,000 users total) into a single tenant in 16 weeks, saving $4.2M in annual licensing costs.
M&A integration budgets are set during deal negotiation and approved by investment committees. Cost overruns are not an option. EPC Group provides fixed-fee migration proposals with clearly defined scope, timeline, and deliverables. If the migration takes longer than planned due to our execution, we absorb the cost. This model has made us the preferred migration partner for PE firms managing portfolio company integrations.
The true cost of migration is not the partner fee. It is the downtime, data loss, compliance gaps, and productivity disruption that result from choosing the wrong approach.
| Factor | EPC Group | Other Partners | DIY (Internal IT) |
|---|---|---|---|
| Migration Speed | 40-60% faster (proprietary tool) | Standard timelines | 2-3x longer |
| Data Loss Risk | Zero (checksum validated) | Low-Medium | Medium-High |
| Downtime | Zero downtime guaranteed | Hours to days | Days to weeks |
| Compliance Handling | HIPAA, SOC 2, FedRAMP expertise | Basic | None typically |
| M&A Experience | 50+ per year | 1-5 per year | None typically |
| Cost Certainty | Fixed-fee pricing | Time and materials | Hidden internal costs |
| Post-Migration Support | 2-4 weeks hypercare | 1 week (if any) | Self-supported |
| Experience Level | Since 1997, 2,000+ migrations | Varies widely | First migration often |
The Hidden Cost of DIY Migration: Organizations that attempt Microsoft 365 migrations internally report an average of 3-5 days of email downtime, 15-20% data loss in SharePoint migrations, and 6-12 months of productivity disruption from poor adoption. The cost of remediation after a failed DIY migration typically exceeds the cost of hiring an experienced partner from the start.
Full lifecycle M365 consulting including deployment, governance, and optimization.
Read guideComplete enterprise guide for migrating on-premises Exchange to Exchange Online.
Read guideDetailed playbook for M&A tenant consolidations and divestitures.
Read guideComprehensive enterprise guide covering all migration scenarios and best practices.
Read guideTenant-to-tenant migration timelines depend on data volume, user count, and complexity. For organizations with 100-500 users: 2-4 weeks. For 500-2,000 users: 4-8 weeks. For 2,000-10,000 users: 8-16 weeks. For 10,000+ users: 3-6 months. EPC Group's proprietary migration tool accelerates timelines by 40-60% compared to native Microsoft tools. Our record is migrating a 15,000-user organization in 6 weeks with zero downtime and a documented 5-day cutover average. Key factors affecting timeline: mailbox sizes, SharePoint data volume, Teams configurations, custom applications, and compliance requirements (HIPAA, SOC 2, FedRAMP add 2-4 weeks for validation).
Microsoft 365 migration costs vary by scope: Quick-Start migrations (under 100 users, basic email and files) start at $15,000. Standard migrations (100-1,000 users, full workload including Teams, SharePoint, and OneDrive) range from $35,000-$75,000. Enterprise migrations (1,000-10,000+ users with compliance requirements, custom integrations, and multi-phase rollout) start at $100,000 and scale based on complexity. Per-user costs typically range from $25-$150 depending on data volume and migration type. EPC Group provides fixed-fee proposals after a discovery assessment, so there are no surprise costs. M&A tenant consolidations are priced separately based on timeline urgency and regulatory requirements.
Yes. EPC Group has completed one of the largest documented Google Workspace to Microsoft 365 migration portfolios in the industry (within an overall enterprise migration base of 1.83M+ users across 216+ M&A / tenant consolidation programs). We migrate: Gmail to Outlook (email, folders, labels, rules), Google Drive to OneDrive and SharePoint (files, permissions, sharing links), Google Calendar to Outlook Calendar (events, recurring meetings, shared calendars), Google Contacts to Exchange contacts, Google Sites to SharePoint, Google Chat and Hangouts history to Teams, and Google Forms to Microsoft Forms. Our proprietary migration tool preserves metadata, timestamps, folder structures, and sharing permissions. We also handle identity migration from Google to Microsoft Entra ID, DNS cutover, and a coexistence period where both platforms run simultaneously.
With EPC Group's migration methodology, email service is never interrupted. We use a coexistence approach: 1) Mail flow is configured so both the source and destination systems receive email simultaneously. 2) Historical email is migrated in background batches during off-hours, typically processing 50-100 GB per hour. 3) A delta sync captures any new email received during migration. 4) DNS MX records are updated during a maintenance window (typically under 30 minutes of potential delay, not downtime). 5) Post-cutover validation confirms all email is accessible. Users continue sending and receiving email throughout the entire process. Our zero-downtime guarantee means no lost emails, no bounced messages, and no gaps in email history.
A tenant-to-tenant migration moves all Microsoft 365 data, identities, and configurations from one Microsoft 365 tenant to another. It is required during: mergers and acquisitions (consolidating two companies into one tenant), divestitures and spin-offs (splitting one tenant into two), rebranding (changing the primary domain), and tenant consolidation (combining multiple tenants acquired over time). EPC Group migrates: user mailboxes, OneDrive files, SharePoint sites and permissions, Teams channels and chat history, Planner boards, Power BI workspaces, Power Automate flows, Entra ID users and groups, conditional access policies, and Intune device configurations. Our M&A migration practice handles 50+ tenant consolidations per year.
EPC Group uses a multi-layer verification methodology: 1) Pre-migration audit catalogs every mailbox, file, site, and team with item counts and sizes. 2) Migration is performed using our proprietary tool with built-in checksum validation for every item transferred. 3) Delta synchronization runs continuously to capture changes made during migration. 4) Post-migration validation compares source and destination item counts, folder structures, and file checksums. 5) User acceptance testing (UAT) period allows end users to verify their data. 6) Source environment is preserved for 30-90 days post-migration as a safety net. Documented data-fidelity checklists cover thousands of migrations since 1997, with per-item source-vs-destination reconciliation before every cutover is signed off.
Yes. EPC Group specializes in migrations for regulated industries. For Healthcare (HIPAA): We execute BAA-compliant migrations with PHI encryption in transit and at rest, audit logging of all data movement, and post-migration HIPAA control validation. For Financial Services (SOC 2): Migrations follow SOC 2 Type II controls with chain-of-custody documentation, encryption, and access logging. For Government (FedRAMP): We migrate to GCC, GCC High, and DoD environments with FedRAMP-aligned consulting expertise tools and personnel with appropriate clearances. For Education (FERPA): Student data is migrated with FERPA-compliant handling and access controls. Each regulated migration includes a compliance validation report that serves as evidence for auditors.
EPC Group's proprietary migration tool was developed over 15 years of enterprise migrations and offers capabilities beyond native Microsoft tools or third-party products like ShareGate or BitTitan. Key features: 1) minimal-disruption migration with continuous coexistence, 2) Parallel batch processing migrating 50-100 GB/hour, 3) Automatic metadata preservation (timestamps, permissions, version history), 4) Built-in checksum validation for every item, 5) Real-time dashboard showing migration progress, errors, and completion estimates, 6) Automatic retry with exponential backoff for throttled API calls, 7) Cross-platform support (Google, Exchange, Lotus Notes, GroupWise to M365), 8) Compliance-grade audit logging for regulated industries. The tool has been used in 2,000+ migrations with a 5-day average cutover.
SharePoint migration is often the most complex workload. EPC Group's approach: 1) Discovery and assessment: Catalog all sites, libraries, lists, custom solutions, workflows, and InfoPath forms. 2) Architecture planning: Design the target SharePoint Online structure (hub sites, communication sites, team sites). 3) Content migration: Move documents with full version history, metadata, and permissions intact. 4) Custom solutions: Rebuild legacy workflows in Power Automate, convert InfoPath forms to Power Apps, and modernize custom web parts. 5) Permissions mapping: Map on-premises AD groups to Entra ID groups and validate access. 6) Search configuration: Rebuild managed properties, result sources, and search verticals. We handle SharePoint Server 2010, 2013, 2016, and 2019 to SharePoint Online migrations.
M&A firms and private equity groups choose EPC Group because: 1) Speed — our proprietary tool completes migrations 40-60% faster than competitors, critical for M&A timelines. 2) Experience — 50+ M&A tenant consolidations per year across healthcare, finance, and technology sectors. 3) Day-1 readiness — we provide Day-1 IT integration plans so acquired employees have access to corporate systems on closing day. 4) Due diligence support — we assess target company M365 environments during due diligence to identify migration risks and costs. 5) Fixed-fee pricing — M&A deals need budget certainty; our fixed-fee model eliminates cost overruns. 6) Compliance continuity — we ensure regulatory compliance (HIPAA, SOC 2) is maintained throughout the transition with no gaps.
Yes. EPC Group has migrated hundreds of organizations from on-premises Exchange (2010, 2013, 2016, 2019) to Exchange Online in Microsoft 365. Our approach: 1) Hybrid configuration: Set up Exchange hybrid to enable coexistence during migration. 2) Staged mailbox moves: Migrate mailboxes in batches during off-hours, starting with pilot users. 3) Public folder migration: Convert public folders to shared mailboxes or Microsoft 365 Groups. 4) Distribution list migration: Migrate distribution lists and convert to Microsoft 365 Groups where appropriate. 5) Archive migration: Move online archives and retain litigation holds. 6) Decommission: Remove on-premises Exchange servers after validation. Typical timeline: 4-12 weeks depending on user count and data volume. We maintain mail flow throughout with zero interruption.
EPC Group follows a proven 6-phase migration methodology: Phase 1 — Discovery & Assessment (1-2 weeks): Inventory source environment, identify risks, define success criteria. Phase 2 — Architecture & Planning (1-2 weeks): Design target environment, create migration runbook, establish rollback plan. Phase 3 — Pilot Migration (1-2 weeks): Migrate 25-50 pilot users, validate all workloads, refine process. Phase 4 — Batch Migration (2-12 weeks): Execute migration in planned batches with continuous monitoring. Phase 5 — Cutover & Validation (1 week): DNS updates, final delta sync, post-migration validation, UAT. Phase 6 — Hypercare & Optimization (2-4 weeks): Dedicated support team, issue resolution, training, and documentation. Every migration includes a dedicated project manager, migration engineer, and 24/7 support during cutover.
Get a free migration assessment from a firm with one of the largest documented enterprise migration portfolios — 1.83M+ users, 216+ M&A / tenant consolidation programs, documented data-fidelity verification, and zero-downtime cutover methodology. Microsoft expertise since 1997.
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EPC Group has documented one of the largest enterprise Microsoft 365 migration portfolios — 1.83M+ users migrated across 216+ M&A / tenant consolidation programs and hundreds of Google-to-M365 conversions. Combined with 6,500+ SharePoint implementations since 1997 of Microsoft expertise.
We migrate from various platforms to Microsoft 365 with minimal disruption to your business. Our migration sources include:
Our proprietary migration tool operates at a speed of 50–100 GB/hour.
Enterprise migrations often fail when vendors overlook complexity. A Google Workspace-to-M365 migration for 20,000 users involves more than just moving email.
This process includes:
Each item has its own mapping, metadata needs, and coexistence challenges.
EPC Group has successfully completed thousands of enterprise migrations since 1997. We handle various scenarios, including:
This Google-to-M365 migration base ranks among the largest documented in the industry, reflecting extensive experience in enterprise-scale cross-platform solutions across an overall migration portfolio of 1.83M+ users.
Mergers, acquisitions, and divestitures often involve tenant-to-tenant migrations. This process moves content from one M365 tenant to another. It is the most complex type of migration.
Successful tenant-to-tenant migrations require:
EPC Group migrates the complete Google Workspace environment to Microsoft 365. This includes:
EPC Group specializes in migrations from Exchange 2010, 2013, 2016, and 2019 to Exchange Online. We offer cutover, staged, and hybrid migration options.
Our services include:
EPC Group focuses on moving SharePoint sites, document libraries, lists, and permissions from SharePoint 2007 to 2019 into SharePoint Online. We guarantee that the following elements are preserved during the migration:
For large environments exceeding 100 TB, we utilize our proprietary tools to migrate data in parallel batches.
EPC Group migrates network file shares and on-premises file servers to SharePoint Online or OneDrive. We ensure permission mapping, folder structure translation, and metadata preservation.
For large file server migrations, we utilize:
IMAP migrations from Lotus Notes, GroupWise, Zimbra, and other legacy email platforms to Exchange Online. EPC Group handles the calendar and contact conversion that generic IMAP tools miss.
EPC Group built a proprietary migration tool specifically for minimal-disruption Microsoft 365 migrations. Its key capabilities:
Document the size of the source environment, data types, custom configurations, and compliance needs. Identify migration risks, including:
Finally, produce a migration runbook and timeline.
Migrate a representative sample — 50–100 users across different data profiles. Validate metadata preservation, permission mapping, and coexistence configuration. Resolve issues before the full migration begins.
Migrate users in waves of 500 to 2,000, based on your organization's size. Each wave includes the same steps for:
Users will receive communications and training before their wave starts.
Complete the final delta sync to capture any changes made after the initial migration.
Next, execute the DNS cutover to redirect mail flow to Exchange Online. Finally, decommission the source systems as planned.
Additionally, provide 30-day hypercare support to address any post-migration issues.
Regulated migrations require more than data transfer. EPC Group handles compliance requirements throughout the migration process.
EPC Group has successfully completed over 10,000 enterprise Microsoft engagements since 1997. Our migration practice includes:
Founder Errin O'Connor is the author of four Microsoft technology books (Microsoft Press; Sams/Pearson).
We hold key Microsoft Solutions Partner designations. The Modern Work designation highlights our expertise in migration. Microsoft field teams frequently refer complex enterprise migrations to EPC Group because of our proven success.
The timeline for migration varies based on the source environment and the number of users involved. Here are some typical durations:
EPC Group offers a detailed timeline during the discovery and assessment phase.
EPC Group has successfully migrated organizations with over 20,000 users. This includes complete Google Workspace-to-M365 migrations that cover all data types.
With more than 3.7 million mailboxes migrated since 1997, we have worked with businesses of all sizes, including:
EPC Group establishes mail coexistence to allow users in both the source and destination environments to send and receive emails during migration. This setup prevents any loss of email access throughout the migration process.
Mail flow is redirected to Exchange Online only after the user's mailbox is fully validated in the new environment.
EPC Group accurately maps Google Drive sharing permissions to SharePoint permissions. However, Google and SharePoint have different permission models. This difference requires some manual cleanup for complex sharing setups.
We document the permission mapping approach and any exceptions during the discovery phase.
EPC Group can migrate from all SharePoint Server versions: 2007, 2010, 2013, 2016, and 2019, to SharePoint Online. Migrating older versions needs extra work to handle unsupported features and outdated content types.
We begin with a discovery phase to identify all compatibility issues before starting the migration.
EPC Group offers 30-day hypercare support following each migration wave. This support includes:
After the hypercare period, clients usually move to EPC Group's managed M365 services or an internal operations team.
EPC Group has completed more enterprise Microsoft 365 migrations than any other consulting firm in North America. We have a track record since 1997 and hold core Microsoft Solutions Partner designations. Our proprietary tools ensure your migration has the expertise it needs.
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