File sharing through Teams uses SharePoint Online by default. However, third-party cloud services can also be allowed: Citrix, DropBox, Box, Google Drive, Egnyte. 3rd party file storage prevents Microsoft from properly auditing the activity on the files. Using multiple sources of file hosting also increases the risks of files being compromised.
By selecting the "Block all" option, you will disable the use of all 3rd party file storage services available in the Teams Files tab.
In the Set section, you can configure one of the following options when you apply the setting:
- Block All: Disables all third-party cloud storage services usage in Teams
- Allow All: Allows all third-party cloud storage services usage in Teams
- Do not modify (Ignore): Office Protect will not monitor nor attempt to modify the setting on the organization. We recommend using this option if your organization requires the use of a subset of cloud storage services.
You can find this setting in the Teams admin center > Teams settings > Files.
Microsoft’s Documentation:
https://learn.microsoft.com/en-us/microsoftteams/settings-policies-reference#files