To achieve near zero downtime in an Office 365 Tenant to Tenant Migration, the best approach is to migrate data in the background before users are switched to the new tenant. This means performing an initial bulk migration, followed by incremental syncs to capture new emails and updates. Once everything is in place, a final cutover is scheduled—usually during off-peak hours—so users experience little to no interruption. Proper user mapping, permission setup, and communication with users are also important. Keeping both tenants running during the transition helps avoid service gaps. Tools like SysInfo Office 365 Tenant to Tenant Migration Tool are often used to manage continuous data syncing and reduce manual effort.
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