When HMC 4.5 was released, Microsoft introduced an OOF transport agent to support Out of Office (OOF) feature for tenants among different organizations within the same HMC environment. This agent, however was not availalbe for HMC 4.0 at that time.
Well, it is now available for HMC 4.0, hooray! 🙂
Hosted Exchange Service - OOF Agent
Contact Your Field Support Representative