Exchange team has released Hosting and Multi-Tenancy Guidance for Exchange Server 2013 document. It is available for download here.
Read the complete blog at https://blogs.technet.com/b/exchange/archive/2013/02/20/hosting-and-multi-tenancy-guidance-for-exchange-server-2013-now-available.aspx
Read my favorites blogs:
Designing a backup less Exchange 2010 Architecture
Microsoft Exchange 2010 CAS Array – Steps and Recommendations
Appear Offline in Microsoft Office Communicator Server 2007
Microsoft Exchange 2010 Test cases