Allow admins to control external sharing by recipient domain

Currently admins have the ability to allow certain users or groups of users to share content externally. While this is a good feature it is too wide open. Several industries are highly regulated and others may have highly proprietary information and it would be nice to control the external domains that these user can share with.

For Example: Let's say Contoso has a tight relationship with Microsoft and it has been approved by Contoso to share Power BI content with any Microsoft employee. It would be nice for the Power BI admin to turn on external sharing and be able to limit it to only those users with an @microsoft.com email address. This would prevent sharing with a competitor or to a personal email where data could be less secure (i.e., hotmail, gmail, etc)