You already know that you can share content stored in SharePoint Online and/or OneDrive for Business with external users member of another organization – this called B2B (Business to Business sharing.
Well, this capability is going to get better as next time (after you enable it) a user shares content in B2B mode, a guest account will be automatically created (if not already existing); before this improvement, the guest account was created only after the external user signed in.
During the preview, this feature is not enabled by default; if you want to start using it you will need to have SharePoint Online PowerShell (minimum version 16.0.8924.1200) module installed (available here https://www.microsoft.com/en-au/download/details.aspx?id=35588)
Enable Azure B2B Integration
First, you need to logon to your Azure AD portal (either from https://aad.portal.azure.com/ or from your Azure portal https://portal.azure.com) and go to the Organization Relationship blade to enable Enable Email One-Time Passcode for guest (if not yet enabled)
Then connect to your SharePoint tenant to turn on the integration
Connect-SPOService -Url https://<your tenant>-admin.sharepoint.com
Set-SPOTenant -EnableAzureADB2BIntegration $true
Set-SPOTenant -SyncAadB2BManagementPolicy $true
If you need to turn it off, just run again the same commands but with $false instead of $true
Set-SPOTenant -EnableAzureADB2BIntegration $false
Set-SPOTenant -SyncAadB2BManagementPolicy $false
In this case, content shared during the preview will need to be shared again.
NOTE you may got an error message when activating EnableAzureADB2BIntegration; this is because the deployment has not yet reached your tenant. Just try again later; it is expected to be completed by end of July
Set-SPOTenant : Setting the property EnableAzureADB2BIntegration is not supported by your version of the service.
At line:1 char:1
+ Set-SPOTenant -EnableAzureADB2BIntegration $true
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [Set-SPOTenant], ServerException
+ FullyQualifiedErrorId : Microsoft.SharePoint.Client.ServerException,Microsoft.Online.SharePoint.PowerShell.SetTe
nant
