Our company got acquired and we must fold our Microsoft 365 tenant into the parent company tenant. 85 mailboxes plus OneDrive. Microsoft has no native tenant-to-tenant button as far as I can tell. How is this normally done?
How to migrate Office 365 from one tenant to another?
Solved Cloud & Migration
MS
Michael Scofield December 5, 2019
3 replies
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Timeline is 6 weeks and the domain name moves across too.
Right, no native button. The working pattern:
1
Create target accounts in the parent tenant first and map source to target addresses in a CSV.
2
Migrate mail with SysTools Office 365 to Office 365 Migrator using admin credentials on both sides. Run a delta pass in week 5 so late mail follows.
3
Domain move is the tricky bit: remove the domain from the source tenant, attach it to the target, then flip primary addresses. Do this in one maintenance window since mail flow blips during the switch.
4
OneDrive moves separately with the same tool's OneDrive module or SharePoint Migration Tool.
Delta pass plus single-window domain flip went exactly to plan. Merged in week 6. Solved.