M365 Changelog: Adjusting Version Retention for Outlook Data Files (PST File Type) on One Drive and SharePoint Online

MC268960 – As communicated in MC256835 (May, 2021), starting August 16th 2021 the service will start retaining 30 days worth of versions for any PST files stored OneDrive for Business and SharePoint Online team site document libraries. This change will prevent cases of previous versions of PST files from quickly consuming available storage.

  • The change will only impact previous versions of PST files stored in your document library storage.

As best practice PST files should not be uploaded on OneDrive for Business and SharePoint Online team site document libraries due to the impact on storage and network bandwidth. When PST files are uploaded on OneDrive for Business and SharePoint Online team site document libraries, Outlook updates PST files generating multiple versions which leads to storage being quickly consumed by the multiple versions of the PST file.

Note: If you wish to opt out of this policy change, the SharePoint Online Management Shell cmdlet is now available. Please make sure you have the latest PowerShell client version 16.0.21411.12000 before executing the following command – Set-SPOTenant – DisableOutlookPSTVersionTrimming $true.

You will have until August 13th 2021 to opt out.This is a one time opt out operation.

  • The Opt out option for cmdlet will have no effect after the deadline.

New behavior will be automatically enabled if you don’t opt out by deadline. Opt out only applies to existing document libraries and does not apply to new doclib created after August 13th 2021.

  • Command: Get-SPOTenant/Set-SPOTenant
  • Parameter: DisableOutlookPSTVersionTrimming
  • Value: True – Opt-out to the versioning change.
  • False – default value

This feature is associated with Microsoft 365 ID 72237

How this will affect your organization:

As part of the change, version history for PST files will be retained for up to 30 days. Document libraries will be updated with new PST version retention limits.

  • Once this change is rolled out to your tenant, versions of PST files stored on in your document library that are older than 30 days will be permanently deleted.
  • The service will always retain a minimum of 30 day worth of PST versions that can be restored from.

What you need to do to prepare:

If you wish to opt out of the PST version retention update, you will need to execute the SharePoint Online Management Shell cmdlet provided in this post. This cmdlet will need to be executed by August 13th 2021. Without the cmdlet, your tenant will be updated to the new versioning settings on August 16th 2021.

If you choose to opt out of the policy change:

  • Existing libraries will not get the new PST version setting and version retention for existing libraries will work the way it does today.
  • Any new libraries or sites created after August 13th 2021, will get the new behavior.

To prevent uploading .PST files from the OneDrive sync app, read Block syncing of specific file types or To move .PST files out of OneDrive, read How to remove an Outlook .pst data file from OneDrive.

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