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M365 Changelog: Adjusting Version Retention for Outlook Data Files (PST File Type)

MC256835 – Updated May 18, 2021: Microsoft has updated the post to provide additional clarity. Thank you for your feedback.

The PST version retention policy changes are being introduced to address concerns around storage impact of PST versions and will ensure PST file versions no longer consume storage for extended periods. When PST files are uploaded on OneDrive for Business and SharePoint Online team site document libraries, Outlook constantly updates PST files generating multiple versions which leads to storage being quickly consumed by the multiple versions of the PST file. With these changes the service will always retain a minimum of 30 day worth of PST versions that can be restored from.

Note: These changes will have no impact on the actual PST file itself which will continue to be available.

Starting June 28th admins can download the latest version of the SharePoint Management Shell and start opting out using SharePoint Online Management Shell cmdlet provided below. You will have until August 16th to opt out.

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

Note: Microsoft does not recommend uploading PST files due to the impact they have on network bandwidth and storage:

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

Starting August 16 2021, Microsoft will be introducing new retention policies for Outlook Data Files (PST File type) Versions to prevent them from consuming storage capacity for OneDrive & SharePoint Online.

The new policy will limit the number of PST versions retained, resulting in greater storage capacity from PST version storage.

With this new retention policy, PST file versions will be retained for up to 30 days.

Key points:

Timing: August 13, 2021
Action: To opt out, prepare and execute a SharePoint Online Management Shell cmdlet (Set-SPOTenant cmdlet)
Review, assess and to opt out, take action by August 13th, 2021

How this will affect your organization:

As part of the change, up to 30 PST versions in 30 days will be retained. Document libraries will be updated with new PST limits. Once this change is rolled out to your tenant, PST versions older than 30 days will be permanently deleted.

If you wish to opt out of the PST version retention update, you will need to execute a SharePoint Online Management Shell cmdlet (Set-SPOTenant cmdlet). 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 the tenant opts out:

Existing libraries will not get the new PST setting and version retention for existing libraries will work the way it does today.
Any new libraries or sites created after the policy is turned on, will get the new behavior.

What you need to do to prepare:

If you wish to opt out of the PST versioning setting update, you can start today by using SharePoint Online Management Shell cmdlet.Additional information