This setting controls whether users in your organization are allowed to sync OneDrive for Business or SharePoint content that has been shared by users in a different organization. This is a collaboration feature called B2B Sync.
If you enable this setting, users will not be able to start syncing a OneDrive for Business or SharePoint library or folder that was shared from an external organization. Any shared libraries or folders already being synced will stop syncing.
If you disable or do not configure this setting, users will be able to sync OneDrive for Business and SharePoint libraries and folders that have been shared from external organizations.
For more info about B2B Sync, see: https://docs.microsoft.com/en-us/onedrive/b2b-sync
| Registry Hive | HKEY_LOCAL_MACHINE |
| Registry Path | SOFTWARE\Policies\Microsoft\OneDrive |
| Value Name | BlockExternalSync |
| Value Type | REG_DWORD |
| Enabled Value | 1 |
| Disabled Value | 0 |