Understanding Changes in Email Modification Timestamps After March 2024 Exchange Online Update


On March 26, 2024, Microsoft released an update to Exchange Online servers that initiated a re-indexing process for all tenants. This update led to some changes in email properties, which impacted how Spanning Backup for Microsoft 365 displays and restores emails.

Key Points

  • Microsoft Update: The update caused a re-indexing process that affected email properties.
  • Impact on Email Properties: The re-indexing process randomly altered various properties of emails.
  • Modification Timestamps: Due to these changes, Spanning Backup had to update the modification timestamps on affected emails as they were flagged as changed by Microsoft's API.
  • Email Display in Spanning Backup: In the restore mail view, Spanning Backup displays emails based on their modification time rather than the sent/received time. As a result, some older emails may appear with modification dates that do not match their original sent/received dates.

Important Notes

  • No Data Loss: Despite these changes, no email data was lost.
  • Modification Date Discrepancies: Some emails may show a more recent modification date than their original sent/received date.


The recent Microsoft update to Exchange Online has led to necessary adjustments in how Spanning Backup manages and displays emails. While the modification timestamps on some emails may appear altered, rest assured that no email data has been lost. If you have any concerns or need further assistance, please contact our support team.

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