6 min read
Most Microsoft 365 migrations fail on people and sequencing rather than technology. Mailboxes move reliably; expectations do not.
Start with an inventory: mailboxes and their sizes, shared mailboxes, distribution lists, file shares, identity sources and any application that sends email through your current platform. Applications that authenticate against legacy mail are the most common cause of post-cutover surprises.
Decide the identity model before touching mail. Where user accounts live, how passwords are managed and how multi-factor authentication will be enforced shapes every later step.
Pilot with a representative group, not with the most technical staff. Then plan the cutover window around the business calendar, and keep a documented rollback position for each stage.
Finally, budget for the two weeks after go-live. Adoption support, permissions cleanup and mobile device reconfiguration are part of the project, not an afterthought.