Quick Answer

Microsoft 365 migration services move your email, files, sites, and collaboration off on-premises servers or fragmented tenants into Exchange Online, SharePoint Online, OneDrive, and Teams, without losing the identity and access your people depend on. i3solutions is a U.S.-based Microsoft partner that has delivered Microsoft 365 migrations since the platform launched, for enterprise and federal organizations, including regulated and post-merger environments. Senior, U.S.-based engineers sequence the work in waves: decide the end state, secure identity and cross-tenant access, then move content under governance you can show an auditor. Most engagements begin with a migration assessment that maps your estate and the risks that stall cutover before any data moves, and you can ask for comparable engagements to share with your committee before you commit.

Proof, not promises. For the Millennium Challenge Corporation (MCC), a U.S. federal agency, i3solutions planned and executed a migration from an unsupported SharePoint 2010 environment to SharePoint 2019 and Office 365, with continuity of operations as the priority. Using ShareGate automation, the engagement reduced migration downtime from weeks to just hours. Retiring on-premises infrastructure eliminated about $500,000 per year in hosting, licensing, and maintenance costs, and the new environment saves staff more than 20,000 productive hours annually, valued at over $200,000 in efficiency gains. Read the MCC case study

For the Logistics Management Institute (LMI), a federal research-and-consulting organization, i3solutions delivered a unified Office 365 environment with Okta single sign-on, consolidating a fragmented estate into one governed Microsoft 365 workspace. Read the LMI case study

The same senior, U.S.-based engineers who scope this work do the build. Every outcome above is quoted from the client’s published case study.

Key Takeaways

i3solutions has delivered Microsoft 365 migrations since the platform launched, and senior, U.S.-based engineers run each one as both a migration and a compliance event.
A Microsoft 365 migration moves several workloads on one timeline: email into Exchange Online, files and sites into SharePoint Online, home drives into OneDrive, and Teams with the SharePoint sites behind it.
Identity has to resolve before any content moves, or people lose access on day one, so i3solutions secures identity and cross-tenant access first.
i3solutions chooses among cutover, staged, hybrid, and tenant-to-tenant paths based on your estate size, compliance constraints, and tolerance for coexistence.
For the Millennium Challenge Corporation, i3solutions cut migration downtime from weeks to hours and retired on-premises infrastructure that had cost about $500,000 a year.

MICROSOFT 365

Microsoft 365 Migration Services

i3Solutions delivers Microsoft 365 migration services for enterprises consolidating tenants after a merger, where migrations break on identity and coexistence, not on copying mailboxes, which is why a cross-tenant move needs an identity and domain map up front and a wave-based cutover that validates each wave.

Due to its incomparable business advantages, migrating to Microsoft 365 is an important strategic step for organizations that want to create an effective workspace. Its complete suite of business data analytics, collaboration and productivity tools make it a great investment for organizations that want to explore the security and flexibility of cloud-based solutions. Through i3Solutions’ Microsoft 365 migration services, we enable smooth migration of on-premises, cloud and hybrid solutions while preserving the integrity and efficiency of the migrated solution.

We are

recognized as a Microsoft partner,

and have been providing Microsoft 365 services since the product was initially launched. Our consultants are also certified by Microsoft in:

Application Development
Data Analytics
Devices and Deployment
Midmarket Solutions

Dual-tenant complexity after a merger is a sequencing problem, not just a migration. The first decision is the end state, consolidate to one tenant or operate multi-tenant deliberately, and everything else follows from it.

Identity and cross-tenant collaboration have to be secured before content moves, or people lose access on day one; consolidation rushed ahead of identity and governance is exactly where M&A IT integrations stall. i3Solutions runs dual-tenant Microsoft 365 integrations with senior, US-based engineers and a sequenced plan the business can stand behind.

Area	M&A risk	What i3Solutions does
Identity	Duplicate/conflicting accounts	Identity + domain map before any move
Coexistence	Collaboration breaks mid-migration	Mail/Teams coexistence stood up first
Cutover	Big-bang failure	Wave-based, validated per workload
Security baselines	Two non-matching standards	Reconciled to one compliance baseline

i3Solutions runs Microsoft 365 migrations and identity integrations for enterprise and federal clients, including a unified Office 365 environment with Okta single sign-on for a federal research-and-consulting organization.

What a Microsoft 365 migration actually moves

A Microsoft 365 migration is rarely one move. It is several workloads with different rules, run on one timeline.

Exchange and email. Mailboxes, shared mailboxes, distribution lists, calendars, and mail flow move into Exchange Online. The work that decides success is mail coexistence and the MX cutover, so messages route correctly while both environments are live.
Files and SharePoint. Document libraries, site collections, and the permissions attached to them move into SharePoint Online. Unmapped permissions and undocumented customizations are where these moves stall, not the file copy.
OneDrive. Personal and home-drive content moves into OneDrive for Business, with the redirection and sync rules that keep people working through the change.
Teams. Channels, files, and the SharePoint sites behind them move together, because a Teams migration that ignores the underlying SharePoint structure breaks links after cutover.
Identity underneath all of it. Accounts, groups, and access have to resolve before content moves, or people lose access on day one.

i3solutions’ Microsoft 365 Migration Services Models

We offer our clients a variety of Microsoft 365 migration models to choose from, depending on their corporate environment and migration needs. These include:

Cutover
Model

Migrate all your existing data, including existing mailboxes, distribution groups and contacts, at once. This model is available to organizations that do not need to migrate a lot of data.

Staged
Model

Migrate all your data in batches, over a period of time. This migration option suits organizations that have large bulks of content, including diverse customizations and integrations.

Hybrid
Model

Integrate Microsoft 365 solutions with on-premises servers, distributing migrated data and services between both environments. This migration approach makes sense for organizations that are not ready for a full implementation of cloud solutions.

Identity
Model

Standard identity: Migrate user accounts to the cloud while data remains on-premises.

Synchronized identity: Migrate all data to the cloud while managing users on-premises.

Federated identity: Migrate all data to the cloud and maintain users with single-sign-on capabilities.

Migration paths, and how we choose one

Cutover migration moves everyone in a single window. It suits smaller estates, roughly a few hundred mailboxes or fewer, where a short, well-rehearsed switch is lower risk than a long coexistence.
Staged migration moves the estate in waves, validating each wave before the next. It suits larger or regulated estates where you cannot afford a single high-risk weekend.
Hybrid migration keeps on-premises and cloud running together for an extended period. It suits organizations that need to move gradually, keep some workloads on-premises, or maintain coexistence during a long program.
Tenant-to-tenant migration moves between two Microsoft 365 tenants, the pattern after a merger or divestiture. Here the hard part is identity and domain mapping and cross-tenant access, not copying mailboxes. A cross-tenant move needs an identity and domain map up front and a wave-based cutover that validates each wave.

We choose the path from your estate size, your compliance constraints, and your tolerance for coexistence, and we decide the end state before anything moves. The common failure we are called in to fix is a migration that started by copying content before identity and governance were settled, which is exactly where post-merger integrations stall.

Microsoft 365 migration services for efficient data transfer and cloud integration. Expert support f.

Benefits of Microsoft 365 Migration Services

Microsoft 365 is the productivity suite of choice for organizations that want to leverage the power, flexibility and cost-efficiency of cloud-based solutions. There are several advantages of migrating to Microsoft 365.

Improved collaboration and teamwork

Microsoft 365 provides everything organizations need to operate while optimizing performance.
Provides all the productivity tools you need in one place, accessible from anywhere, at any time.

Cost savings on IT resources

Save costs on expensive on-premises server maintenance and updates.
Reduce overall IT budgets and spending.

Optimized infrastructure

After migrating to the cloud, organizations can significantly reduce IT department workload.
Free up time for more critical tasks such as innovation.

Powerful analytics

With tools such as Power BI and Microsoft MyAnalytics, organizations can access powerful data visualization and analysis tools.

Advanced security and data protection

Microsoft 365’s rights managementservices, alongside its proprietary encryption and data loss prevention software, enable heightened security for enterprise data assets.

Support and maintenance

Migrating to Microsoft 365 shifts the burden of support and maintenance of enterprise applications to the cloud solutions provider.
Provides significant time and resource savings.

Connected cloud environment

Microsoft 365 functions as a powerful focal point for integration of existing enterprise solutions.

Microsoft 365 migration services we provide

Our Microsoft 365 migration services take into account the varying and evolving needs of our clients as they transition from their on-premises or legacy solutions to the cloud. As a result, we provide:

Migration of data to Microsoft 365 platform for enhanced collaboration.

Strategic Planning: Our process begins with an in-depth review of the deployment and its overall structure. This enables us isolate software inconsistencies and redundant components, as well as other potential flaws so we can fix them before commencing the migration.

Expert Microsoft 365 migration services for seamless business transition.

Migration: Depending on the peculiar requirements of the deployment, we carry out the migration in line with the applicable model while ensuring quick turnaround and data integrity. In required cases, we are able to carry out the migration with little or no downtime.

Cloud infrastructure with network and server icons for business IT solutions.

Integration: We can integrate the migrated solution with other cloud applications or on-premises solutions to improve functionality and increase control over cross-system business processes.

Illustration of a magnifying glass with an exclamation mark and gear, symbolizing troubleshooting in.

Support: We provide ongoing support to our clients to aid user adoption and ensure the continued viability and functionality of the deployment.

Microsoft 365 migration process with checklist and online learning icon.

Training: We provide training for our client’s users and admins to help improve capacity to manage and use the migrated solution effectively. This includes explaining how to ensure the security, stability and effective use of the suite.

Challenges we solve

i3solutions is highly experienced with Microsoft 365 migration and integration and are able to solve a variety of challenges that commonly interfere with the smooth migration of solutions including:

User
Adoption

Stalled
Migration

Obstacles
with Hybrid
Migration

Added
Complexity
of Custom
Solutions

Security
and
Compliance
Issues

Challenges

Stalled migration: A migration project can experience hiccups due to a number of issues including inadequate assessment of deployment complexity or scope before attempting migration. We can help you ensure a smooth and hitch-free process when you work with us.
Obstacles with hybrid migration: Disruptions may arise in a hybrid migration when the process is not conducted with necessary attention to each migration detail. Organizations that work with us can expect a process free of complications as they benefit from our extensive experience and deep expertise with hybrid migrations.
Added complexity of custom solutions: Moving custom on-premises solutions can be quite tricky as this will often require additional development efforts to bring them in line with the requirements of the cloud environment. Our consultants are highly skilled and have no problems with managing the additional demands of migrating custom solutions.
Security and compliance issues: Security and compliance requirements can add an extra layer of complexity to migration projects. The consultants at i3solutions are Microsoft certified and can implement your migration in line with industry standards and internal policies.
User adoption: Migrated solutions can be difficult to get used to, especially where they significantly change the landscape and structure of the existing system. We provide training and ongoing support to boost user understanding and proficiency with the migrated solution, thereby enhancing user adoption.

Security, compliance, and data residency

For regulated and federal organizations, the migration is also a compliance event, and senior, U.S.-based engineers run it for exactly that reason.

Identity and access. Conditional access, MFA, and least-privilege groups are configured before content moves, so the new environment is governed from day one rather than hardened after the fact.
Data residency. Where data lives matters for federal and regulated work. We migrate into the tenant configuration your compliance posture requires, including GCC and other regulated environments, and confirm residency before content moves.
Retention and records. Retention labels, legal holds, and records policies move with the content, so a migration does not quietly drop an obligation you are required to keep.
Audit evidence. We document the estate, the decisions, and the cutover as artifacts you can hand to an auditor or a board. The standard the work is held to is modernization without audit risk.

What we do for our clients

We have assisted clients in a variety of industries with strategizing on the most beneficial options for their migration projects and implementing their deployment according to plan. Our clients routinely request us to assist with:

Cloud data migration process for Microsoft 365 with IT professionals managing data transfer.

Moving content into Cloud
and Collaboration spaces

We are highly experienced at migrations involving the major productivity suites including SharePoint Online, SharePoint 2013 & 2016 and Microsoft Exchange.

Person accessing secure cloud data on a large digital screen.

Configuring remote
access and permissions

We help our clients create effective remote workspaces for their workers.

Microsoft 365 migration process with i3solutions experts.

Setting up remote
collaboration sites

We assist with setting up virtual meetings and conference rooms and resources that enhance collaboration without geographical limitation.

Microsoft 365 migration services for smooth business transition.

Configuring Teams sites

We are routinely asked to help set up Microsoft Teams sites to enable your workforce to be engaged, share documents and review projects with ease.

Illustration of Microsoft 365 migration process with team members and digital tools.

Converting forms to be available
offline

We can convert your forms so they’re available to remote employees to boost productivity and improve workflow processes.

i3solutions can also:

Assist with training users on collaboration tools	Establish virtual meeting/conference rooms
Improve search and discovery through Machine Learning and Natural Language Processing (NLP) based search	Create forms and workflows to automate processes for the remote workforce
Institute metadata and the categorization of data to improve the ability to find the right information	Implement Workflows to track the progress of tasks
Help to secure data and documents	Build Dashboards to provide better visibility into projects and personnel status
Convert applications to be Mobile friendly	Setup Chat and Mobile work spaces

How we sequence a cutover

Every i3solutions migration follows the same order, because the order is what prevents day-one failures.

Decide the end state. Consolidate to one tenant or operate multi-tenant deliberately. Everything else follows from that decision.
Map identity and the estate. Accounts, domains, groups, permissions, customizations, and workflows are inventoried before a plan is built, not discovered mid-cutover.
Secure identity and cross-tenant access. People must authenticate and reach what they are entitled to before content migrates.
Move content in governed waves. Each wave is validated before the next, so problems surface at wave scale, not estate scale.
Stabilize after cutover. Mail flow, sync, permissions, and access are verified, and the old environment is retired on a schedule, not abandoned.

This is the sequence that took the Millennium Challenge Corporation from an unsupported SharePoint 2010 estate to Microsoft 365 with migration downtime measured in hours rather than weeks.

We can handle your Microsoft 365 migration needs

i3solutions’ consultants are highly skilled and experienced. We have been assisting clients for more than 20 years on Microsoft 365 deployments of all sizes and complexity. We can handle your migration needs as well.

Contact us at aski3@i3solutions.com and let our Microsoft 365 consulting team advise you of the migration option that best suits your business needs and budget.

Frequently Asked Questions

How do we manage dual-tenant Microsoft complexity after a merger?

Treat it as a sequencing problem, not just a migration. Decide the end state first, consolidate to one tenant or operate multi-tenant deliberately, because everything else follows from that. Then secure identity and cross-tenant collaboration before any content moves, or people lose access on day one.

Should we consolidate to one Microsoft 365 tenant or stay multi-tenant after an acquisition?

Consolidate when you want one unified operating model and can run the larger project to get there; operate multi-tenant deliberately when the businesses must stay separate for legal or operational reasons. Consolidation simplifies governance and cost; deliberate multi-tenant preserves separation. The wrong move is drifting into multi-tenant by inaction, which leaves governance and identity half-integrated.

What has to be secured before we move content between merged tenants?

Identity and cross-tenant collaboration come first. Users need to authenticate and reach what they are entitled to across the boundary before content migrates, or the move breaks access on day one. Consolidation rushed ahead of identity and governance is exactly where M&A IT integrations stall.

Why do post-merger Microsoft 365 integrations stall?

They stall when content migration is rushed ahead of identity, security, and governance. The transfer looks like the project, so teams start there, then hit access, compliance, and ownership problems that should have been sequenced first. Deciding the end state and securing identity up front is what keeps the integration moving.

How long does a dual-tenant Microsoft 365 integration take?

It varies with the end state and the size of the estate, but the sequence matters more than the calendar: end-state decision, then identity and cross-tenant access, then content in governed waves. Trying to compress that order is what creates the day-one access failures. i3 runs dual-tenant Microsoft 365 integrations with senior, US-based engineers and a sequenced plan the business can stand behind.

About the Author

By Justin Bowen, Sr. Vice President, Delivery Services, i3solutions

Justin has spent more than 15 years at i3solutions and more than 25 years leading project, program, and product delivery across complex technology environments. His work centers on turning strategy into governed execution, aligning technical teams and stakeholders, managing delivery risk, and guiding Microsoft 365, SharePoint, Power Platform, cloud, data, automation, and custom application programs through measurable production outcomes.

Updated June 26, 2026