In Windows Server Essentials 2012 R2, all of our online services integration features, including Azure Active Directory and Office 365, are supported only in environments that have a single domain controller. In environments with more than one domain controller, integration of these services is blocked due limitations in the user account and password synchronization mechanism in Windows Server Essentials.
I am happy to announce that with the recent Windows August Update released on (8/12/2014, PST), this limitation has been removed. This update adds support for both Azure Active Directory integration and Office 365 integration features in domain environments consisting of a single domain controller, multiple domain controllers, or Windows Server Essentials as a domain member server.
For more information, please go to http://support.microsoft.com/kb/2974308.