The Message Center is the main channel that Microsoft uses to inform admins about changes, maintenance work and updates coming to their service. The weekly digest now brings thei message center notifications directly to your inbox to make it easier for you to stay up to date and to share the notifications with your co-workers. The weekly digest capability is currently available to Office 365 admins who are set to First Release in tenants with more than 50 subscribed users and will become available for all customers over time.