Microsoft 365 & Cloud

How to migrate to Microsoft 365 successfully

3 min read Guillaume Duveau

A successful Microsoft 365 migration depends on a thorough audit beforehand, careful planning, and supported adoption afterwards, in that order, without rushing any of the steps.

Migrating to Microsoft 365 is a common decision for small businesses wanting to make their email reliable, enable remote working, and secure their data. But the technical migration is only part of the picture. What actually determines success is what happens before and after the cutover.

Start with the audit

Before touching anything, take stock of what exists: every mailbox, every distribution group, every delegation, data volumes to migrate, shared network folders, devices and their operating systems.

This is where you find the surprises: forgotten accounts, aliases pointing nowhere, shared drives that nobody uses but nobody has dared to delete. Better to discover these now than at the moment of cutover.

An honest audit also covers real usage patterns: who works remotely, who shares files externally frequently, which business tools connect to the current email system. That information shapes configuration decisions.

Choose the right licence

Three plans cover most small business needs.

Business Basic: professional email, Teams, SharePoint and OneDrive in web and mobile versions. The right choice if web-based office tools are sufficient and nobody needs to install Word or Excel on their computer.

Business Standard: adds the Office applications installed on PC and Mac, but without the advanced security layer. Fine for pure office work, rarely the right choice once there is sensitive data or access to protect.

Business Premium: adds a real security layer, then device management. The security works from day one, well before devices enter the picture: scam emails and dangerous links are filtered before they arrive, sign-ins are checked so a stolen password is not enough, and sharing with outside parties, non-Microsoft tools included, is better controlled. It is the foundation we recommend, and the one our offers are built on. Device management comes next: to understand what it changes in practice, see our article on managed devices.

Plan to avoid disruptions

Migration is not something to improvise. The email cutover, the DNS change that redirects traffic to Microsoft, should happen in the evening or at the weekend, with send and receive tests before closing the old configuration. A phased calendar (a pilot with 10 % of users, then deployment in batches) lets problems be fixed before they affect everyone.

Concrete details to watch: mailbox delegations, automatic signatures, aliases, mobile devices, and shared mailboxes. These are regularly overlooked in rushed migrations and cause visible problems immediately after the cutover.

Organise files before migrating them

A file migration is an opportunity to clean up, not to move disorder to a new location. Before migrating, sort: team data (SharePoint) versus personal work data (OneDrive), active folders versus archives, useful files versus accumulated duplicates.

Set up a clear structure from the start, with sites by department or project and libraries with descriptive names, then document it in a simple naming guide. Two days of work on this prevents months of confusion.

Security from day one

Migration does not postpone security: it triggers it. Enable multi-factor authentication before migrating even the first user. Configure DKIM and DMARC records to protect your sending domain’s reputation. Establish rules around external sharing.

These measures take an hour to put in place and prevent incidents that would take weeks to resolve.

Adoption matters as much as the technical work

The technical migration can go perfectly and still feel like a failure if teams do not understand the new tools. Plan short sessions by team in the first weeks: one hour on Teams, one hour on OneDrive, one hour on Outlook. A one-page guide for the ten most useful commands. An internal champion per department to answer everyday questions.

The goal is for Microsoft 365 to become the normal way of working quickly, not an unfamiliar environment that everyone has to put up with.

To find out more about Microsoft 365 migration and managed IT, visit /en/offers/cloud.

Frequently asked

How long does a Microsoft 365 migration take for a small business?
For an organisation of 25 to 100 users, allow five to seven weeks: one week for audit and preparation, one week for configuration, one week for a pilot, and two to three weeks for phased deployment and adoption support.
Can you migrate without any service interruption?
Yes, with proper planning. The email cutover (DNS change) happens outside business hours, with a transition period where both environments run in parallel to prevent any message loss.
What happens to existing files and emails during the migration?
They are migrated with their content, but some metadata (original creation dates, version history) may be lost depending on the method. A prior inventory and cleanup of obsolete data reduces the risk.
Should users be trained before or after the migration?
During and after. A short session before the cutover to explain what is changing, then brief team-by-team sessions in the first weeks. Ongoing adoption is as important as the technical migration itself.
Which Microsoft 365 licence is right for a small business?
For most SMEs, it is Business Premium, and not only for device management. Its real value is security, useful from day one: scam emails and dangerous links are filtered before they arrive, sign-ins are checked so a stolen password is not enough on its own, and sharing with outside parties, including non-Microsoft tools, is better controlled. Device management comes on top of that. Business Standard or Basic only make sense in limited cases, and we build our offers on Business Premium in any case.

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