After several migration programs and more than 1,000 mailboxes migrated, I can usually tell within the first two weeks whether a project is headed for a smooth cutover or a long post-migration incident. The signs are consistent.
1. The runbook is only a task list. A task list tells the team what to do when things go to plan. A runbook tells them what to do when they don’t. If rollback procedures and failure thresholds aren’t documented before the first batch runs, those calls get made under pressure at cutover.
2. The environment hasn’t been assessed. MigrationWiz trial migrations surface orphaned accounts, mail-enabled objects with no mailbox, and authentication policies that conflict with the destination tenant. That only helps if an engineer reads the item-level error reports. If nobody ran the trial or reviewed the output, those problems wait for cutover.
3. Coexistence isn’t planned. In tenant-to-tenant moves, users on both sides collaborate during the transition. If nobody has defined mail routing between them, calendar sharing, and Teams interoperability, those gaps become urgent after cutover.
4. Identity is a last-week pre-task. Entra ID sync sequence and timing, domain rehoming sequence, and hybrid identity configuration all have to be validated before mailbox migration. Finishing them the week before cutover isn’t validation.
5. There’s no hypercare plan. Without a support structure defined before cutover, the migration engineer becomes the support team. On one program, a five-person team supported 500+ clients through multiple post-migration phases. It worked because the structure was designed before cutover, not assembled from whoever was free afterward.
6. PowerShell isn’t in use. Pre- and post-migration validation gets done one record at a time in admin portals. That doesn’t scale, and the problem compounds during and after cutover.
7. Nobody is talking to users. People who don’t know what is changing, when, or who to call when something breaks flood the help desk. Manageable issues turn into long incidents.
All seven are fixable. The longer you wait to spot them, the more they cost.
Which of these seven is showing up on your project right now?
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