I originally thought of tenant migration and data cleanup as two completely separate projects, but combining them could make sense when moving into a new Microsoft 365 environment.
Microsoft’s cross-tenant documentation confirms that Exchange Online, SharePoint, and OneDrive can all be involved in tenant migrations, particularly in merger, acquisition, divestiture, and restructuring scenarios.
DRS Softech’s Office 365 Tenant to Tenant Migration Tool takes an interesting approach by including deduplication alongside migration. It can scan Microsoft 365 email, contacts, calendars, SharePoint files, and OneDrive data for duplicates using server-side and hash-based methods. Administrators can preview duplicate items, retain the required copy, and reclaim storage without downloading the cloud data first.
That could be useful when consolidating two organizations that have overlapping documents or duplicated mailbox content.
The migration side also covers Exchange Online, SharePoint, and OneDrive, with flexible source-to-target mapping. Advanced filters allow selection based on date range, file size, file extension, content type, created/modified dates, and duplicate detection.
For larger projects, multi-threaded transfers, incremental migration, Active Tasks monitoring, and detailed reports would also be useful for keeping track of progress.
Has anyone here combined data cleanup with a tenant consolidation, or is it safer to complete the migration first and deduplicate afterward?