If you collected mailbox statistics in your on-premises environment before migration, collect statistics for your %BRAND_OFFICE_365_SHORT% ...

If you collected mailbox statistics in your on-premises environment before migration, collect statistics for your %BRAND_OFFICE_365_SHORT% mailboxes to compare item counts. Because the mailboxes remained accessible during migration, you must consider that new mail could have arrived and users could have deleted data since the start of the migration. Review any errors in your migration batches before deleting them.