Microsoft 365 migration checklist for businesses

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.

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.

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. FortLyn's Microsoft 365 Foundation starts at $1,250 for one tenant, one domain, and up to five users within an agreed setup scope. Existing email and data migration are quoted separately; Microsoft licenses are additional. Source systems, data volume, shared access, cleanup, and application dependencies affect the migration estimate. Review FortLyn's pricing and scope when comparing proposals.

Validate before closing the project

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. 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.

Plan the next step

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