A Microsoft 365 migration is easy to underestimate because email is the most visible part.

The real project can include identity, devices, files, permissions, shared mailboxes, Teams, OneDrive, SharePoint, mobile access, DNS, security policies, and the habits employees built around the old environment.

Inventory the current environment

Before moving anything, document:

• domains;
• mailboxes;
• aliases;
• shared mailboxes;
• distribution groups;
• user accounts;
• file shares;
• cloud storage;
• calendars;
• devices;
• mobile access;
• existing Microsoft tenants;
• third-party applications that send email.

Unknown dependencies create cutover surprises.

Clean identity before migration

Decide:

• who is an active employee;
• which accounts should be shared;
• which accounts belong to former employees;
• which addresses are aliases;
• naming standards;
• administrator roles;
• recovery contacts.

A migration is a good time to stop carrying years of identity clutter into the new environment.

Plan files separately from email

File migration deserves its own design.

Determine whether data belongs in:

• OneDrive;
• SharePoint;
• Teams;
• another cloud platform;
• an archive;
• an application.

Do not copy an old shared drive into one giant SharePoint library and call the information architecture finished.

Review permissions

Old file systems often contain permissions nobody remembers assigning.

Ask:

• who actually needs access;
• what should be departmental;
• what should be private;
• what guests or outside parties require;
• what should not be migrated at all.

Simpler permissions are easier to support.

Secure the tenant before the cutover

At minimum, review:

• multi-factor authentication;
• administrator accounts;
• conditional access if licensed and appropriate;
• legacy authentication;
• mailbox forwarding;
• device enrollment requirements;
• external sharing.

Security policy should be intentional rather than added after the first suspicious login.

Test representative users

Do not test only an administrator.

Include users who represent different workflows:

• heavy Outlook user;
• mobile user;
• executive;
• shared mailbox user;
• remote employee;
• employee with large file access;
• employee using third-party applications.

Testing should confirm the real work, not merely that the login succeeds.

Plan DNS and mail flow

Document which records will change and when.

Typical changes may include:

• MX;
• Autodiscover;
• SPF;
• DKIM;
• DMARC;
• verification records.

Also identify devices and applications that send email, such as scanners, websites, line-of-business software, and alerting systems.

Communicate the user experience

Employees need to know:

• what changes;
• when it changes;
• what password or sign-in behavior to expect;
• whether phones need to be reconfigured;
• where files will be;
• who to contact for help.

A technically successful migration can still feel chaotic if users are surprised.

Verify after cutover

Check:

• inbound and outbound email;
• aliases;
• shared mailboxes;
• calendars;
• mobile devices;
• file access;
• Teams;
• scanners/apps sending mail;
• external sharing;
• administrator access;
• backup or retention plan.

Then monitor support patterns for several days.

The migration is complete when the business workflow works, not when the last mailbox reports 100 percent copied.

That is the mindset behind Loginect’s Infrastructure & Business IT and Data & Cloud Applications work.