Does anybody know what this requirement for EX Hybrid 2013 means?
We have a large EX 2013 environment with dedicated CAS and Mailbox servers, there is no server which holds both roles. The first sentence in the statement states that at least one multirole server is a hard requirement but the second sentence states, that it is only recommended.
Exchange Hybrid Requirement
Exchange 2013: At least one server with the Mailbox and Client Access server roles installed. While it's possible to install the Mailbox and Client Access roles on separate servers, we strongly recommend that you install both roles on each server to provide additional reliability and improved performance.