Announcing GA: Mark new files as "sensitive by default" in OneDrive & SharePoint

Published Jul 07 2020 05:05 PM 3,892 Views

What does this feature do?

When new files are added to SharePoint or OneDrive in Microsoft 365, it takes a while for them to be crawled and indexed. It takes additional time for the Office Data Loss Prevention (DLP) policy to scan the content and apply rules to help protect sensitive content. If external sharing is turned on, sensitive content could be shared and accessed by guests before the Office DLP rule finishes processing.

Instead of turning off external sharing entirely, you can address this issue by using a new PowerShell cmdlet. The cmdlet prevents guests from accessing newly added files until at least one Office DLP policy scans the content of the file. If the file has no sensitive content based on the DLP policy, then guests can access the file. If the policy identifies sensitive content, then guests will not be able to access the file. Read here for more details. It is worth mentioning that we have the scan performance much better so that external users do have have to wait long before accessing a non-sensitive file. In 95% of the cases the entire process should be done in less than 5 minutes


Quick reference to the PowerShell switch:

Set-SPOTenant -MarkNewFilesSensitiveByDefault BlockExternalSharing

Occasional Visitor

Hi, just a question for clarity. What is the user experience for this? . If a user uploads a file and then immediately externally shares it, is it :-

blocked and prevented from being shared until a DLP scans it or

The external user is unable to access the file and must wait until the DLP scan has run. What error message does the external user get to say that the file cannot be accessed until it's been scanned?



@NigelG  The file is blocked immediately till DLP scan is complete


@Sanjoyan Mustafi 


I tried this new feature. I run the cmdlet in my tenant Set-SPOTenant -MarkNewFilesSensitiveByDefault BlockExternalSharing
But it does not work as expected. I still can share file with sensitive info to external users as soon as the file is uploaded to SharePoint. I also setup policy location as "include all SharePoint sites and OneDrive accounts and exclude none"


Any idea?


Thanks in advance

@px091  Please open a  support ticket and share the details with me. I will help. 

Regular Visitor
  1. Can the PS command be scoped to a group of test users?
  2. Also can this work with MCAS, if MCAS  is scanning those files instead of Microsoft Office DLP
  3. If we have 3 policies 1 for PII, 1 for PHI, 1 for PCI if a file is scanned by either one that validates it as scanned and it removes the sensitivity? So if the policy precedence is for PCI then if there is PHI or PII content what happens?
  4. What are the license restrictions to use this with Microsoft office dlp? 
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