Microsoft technicians are continuing to run diagnostics on the server to determine the cause of the problem. We do not have an estimated time when service might be restored as this estimate is dependent on the diagnosis of the problem. We do know that the server is attempting failover, but cannot bring all services online in order to restart. Incoming and outgoing email is being queued for delivery when service is restored.
More information and a list of affected departments can be found on the Exchange Bulletin page.