On one program, a five-person hypercare team supported 500+ clients without routing every issue to the lead engineer. The runbook made that possible.

Migrations that go wrong usually have capable engineers and thin documentation. The gap shows up as ad-hoc decisions under pressure during the migration window, inconsistent client support, and no audit trail when someone asks what moved and when.

Here are the five documents I build, in order:

1. The runbook. It exists before any tool is configured, and it’s a decision document, not a task list. It says what to do when item-level error rates pass a threshold, what the rollback triggers are, and who can decide alone versus who must escalate.

2. The pre-migration environment assessment. Document source and target tenant health before migration starts: Entra ID object counts, mail flow dependencies, legacy authentication configurations, and hybrid sync state. Anything unresolved will cause problems when the first MigrationWiz batch runs.

3. The batch execution log. Tracking which accounts migrated in each pass creates the audit trail for post-migration support. The MigrationWiz item-level report holds the item counts and error summaries. Six months after cutover, when a user says email is missing, the log tells you whether the item failed or migrated.

4. The coexistence and mail-flow map. Document how mail flows between source and destination during the transition: MX records, routing connectors, transport rules, and SPF/DKIM configuration. When mail flow breaks in the first 48 hours after cutover, the map tells you where to look.

5. The knowledge transfer package. What you hand the steady-state team decides whether they can maintain what you built without calling you. If it doesn’t exist, you are the documentation, and that doesn’t scale.

What documentation on your migration project did a person write, not a tool?

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