A nice new feature that Microsoft has added across SharePoint Online, including OneDrive for Business, is the ability to whitelist or blacklist domains for sharing.
You’ll need to login to the Office 365 web console as an administrator. You’ll then need to navigate to the Office 365 Admin center as shown above.
From here, select the Admin icon on the left and then SharePoint from the menu that appears.
From the menu that appears on the left select sharing.
You should now see the sharing control options as displayed above.
Under the Additional settings, when you select the option Limit external sharing using domains the above box and selector appears.
Here you can now prevent sharing to specific domains by selecting the Don’t allow haring with users from these blocked domains or only allowing sharing to specified domains using the Allow sharing only with users from these domains option..
Thus you can either block a list of domains or allow access only to a list of domains, you can’t do both simultaneously.
Once you apply these settings they will be applied across both Teams Sites and OneDrive for Business for all users.
This now gives you an easy method of controlling which domains you allow your users to share information with across everything in SharePoint Online.