Microsoft 365 migration checklist for small businesses

Reviewed November 6, 2026 · FortLyn

What should you check before migrating Microsoft 365?

Confirm the source and destination, administrative access, the information that must move, a tested migration method, and the person who will accept the finished work. Email, files, calendars, and business applications have different dependencies. Moving one does not automatically move the others.

If accounts and information are staying in the same Microsoft 365 organization, a licensing or plan change may not require a data migration. Confirm license assignments, the services included in each plan, and subscription commitments before replacing or cancelling existing licenses.

Need help planning your Microsoft 365 move?

Tell us your current email provider, approximate user count, where your shared files live, and your preferred timing. FortLyn will review your starting point and clarify the scope, fees, and next steps before work begins.

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Is this a licensing change or a data migration?

Changing the company that supplies your Microsoft licenses does not always require moving your email and files. First confirm whether you are keeping your existing Microsoft 365 tenant—the business account that holds your users and services—or moving to a different one.

Keep Microsoft 365 and change licensing provider

What the work involves: A subscription or provider transition that can use your existing tenant, rather than a new mailbox and file migration.

What to confirm first: Who controls the tenant, your current subscription arrangements, and the cooperation needed from the providers involved.

Move email from another service into Microsoft 365

What the work involves: A data migration using a method suited to the source system and the information you need to keep.

What to confirm first: Whether the method covers email only or also calendars, contacts, and other required information.

Move between two Microsoft 365 tenants

What the work involves: A separate migration between business environments; changing the licensing provider alone does not perform this move.

What to confirm first: The source and destination, the workloads in scope, and how required access will work afterward.

For an eligible Cloud Solution Provider (CSP) subscription transfer, both the current and receiving providers must approve the transfer. FortLyn coordinates with its distributor where required and confirms the applicable route before agreeing to a change date.

Microsoft guidance on changing subscription channels within an existing tenant
Microsoft CSP subscription-transfer requirements

Build the migration inventory

• Users, active mailboxes, aliases, shared mailboxes, and distribution groups.
• Domain and DNS providers, subscription owners, and authorized administrators.
• Shared files, access groups, external sharing, and information that must remain available.
• Applications, scanners, and business processes that send email or depend on existing accounts.
• Devices and applications employees use, including compatibility questions.

Give each workload a business owner. Record unknowns as open decisions and confirm who can authorize account, domain, and data changes.

Agree what moves and how

Identify what moves, what stays, and what needs an archive or separate project. Source platforms, data volume, permissions, and workloads affect the method. Confirm licensing and migration-tool requirements before committing to the scope. Microsoft provides business setup planning guidance for preparing the destination environment.

What does the migration method actually cover?

An email migration method is not a promise that every part of your working setup will move. Confirm its coverage before treating a transfer as a complete business move.

Email migration using IMAP

What it covers: Messages in the mailbox's inbox and other mail folders.

What needs separate attention: IMAP does not migrate contacts, calendar items, or tasks. Agree a separate approach for any of these that you need to retain.

Destination mailboxes for an IMAP move

What it covers: The existing Microsoft 365 mailboxes that receive the copied email.

What needs separate attention: Create the destination mailboxes before the transfer; IMAP migration does not create them.

Mail flow after an IMAP migration finishes

What it covers: The email already transferred by the completed migration.

What needs separate attention: New messages still delivered to the old system are not copied after the migration is finished. Include final mail-flow checks in the agreed change plan.

These are IMAP-specific limits. A different source or migration method may handle the workloads differently. FortLyn confirms the method and included workloads in the project scope.

Microsoft's comparison of email migration methods

SharePoint and OneDrive migration checklist

Plan shared files separately from email. Before moving content, agree where each folder belongs and who should be able to use it.

• Map each source folder to its destination site, library, or user account.
• Identify content owners, approved access groups, and external collaborators.
• Review duplicate, obsolete, or restricted material with the business owner before deciding what to move.
• Run the chosen tool’s assessment or scan and resolve reported blockers before the main transfer.
• Pilot representative files, permissions, shared links, and everyday collaboration tasks.
• Record failed or excluded items, verify the destination with its owner, and agree how changes made during the move will be handled.

Microsoft’s Migration Manager overview explains file-share migration, prescans, and migration reporting. The appropriate tool and approach depend on your source and destination.

Run a representative pilot

Select users whose work includes shared information and delegated access where relevant. Test sign-in, sending and receiving mail, calendars, file access, and essential applications. Record results and resolve material problems before expanding the move. A transfer report alone does not establish that employees can work.

Five go/no-go checks before cutover

1. Access: authorized administrators can reach the source, destination, and DNS provider when needed.
2. Destination: required users, licenses, mailboxes, and permissions are ready for the chosen migration method.
3. Pilot: representative users can complete agreed daily tasks and material failures are resolved.
4. Continuity: staff know the change window, support route, and what happens if the move must pause.
5. Acceptance: a named business owner has agreed the tests and how outstanding items will be handled.

Assign the technical owner, decision-maker, and staff communication contact. Agree fallback decisions and data-protection arrangements for the scope. Schedule post-change support before starting the change.

Will connecting the domain affect the website?

Connecting a domain to Microsoft 365 does not require moving the website. Preserve the records used by the website and other services when making approved DNS changes. Microsoft advises preparing users and mailboxes before switching the MX record, which changes where new email is delivered. See Microsoft’s custom-domain setup guidance.

Is migration included in the setup price?

Not automatically. Migration is included only when the proposal expressly defines its source systems, data allowance, permissions, cleanup, validation, and handover. FortLyn quotes implementation and migration by agreed scope; standard hourly consulting and implementation is $300 per hour, plus applicable tax. Microsoft subscriptions and approved third-party costs are additional. Review FortLyn’s engagement and project investment options when comparing proposals.

Check email signatures after the move

Confirm sender details, logos, reply layouts, and signature placement in the email apps your team uses. If signatures need central management, explore Microsoft 365 email signature setup with CodeTwo.

Validate before closing the project

For each workload, record its owner, the test performed, the result, and any remaining action. Check mail flow, required data, permissions, and everyday tasks against the acceptance checklist. Log unresolved items with owners and dates. Hand over administrative responsibilities, operating notes, and the support route. Review your onboarding and offboarding process so future staff changes follow the new setup. Avoid committing to a schedule or downtime promise before discovery and testing.

When can we cancel the old provider?

After agreed validation and handover, once required information is accounted for and the business has confirmed its retention and recovery needs. Check for archives, forwarding, applications, or billing dependencies that still rely on the old service. Assign responsibility for cancellation so the account is not shut down before these checks are complete.

Completing the technical work does not necessarily end an existing subscription commitment. Record each service’s renewal or commitment end date, who will request cancellation, and who will verify the confirmation before treating the old arrangement as closed.

Before you request a migration quote

Bring these five details to your first planning conversation. Approximate counts are enough to start; discovery confirms the final scope.

• People: the number of users, shared mailboxes, and locations involved.
• Current systems: your email provider and where shared files are stored.
• Data: approximate mailbox and file volume, plus any archives that must remain available.
• Access: who manages your domain, Microsoft tenant, and existing accounts.
• Timing: your preferred move date, busy periods to avoid, and who will approve the result.

Planning a Microsoft 365 migration? Request a quote. FortLyn will review your starting point before confirming scope, fees, and timing.

Explore Microsoft 365 services, read the business IT preparation guide, or start a Technology & Workflow Review to define the work.

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