Hosted email infrastructure is an example for?

Question: Hosted email infrastructure is an  example for? 

1-Hosted email infrastructure is an instance of SaaS.2- Amazon Web Services is an instance of IaaS. Currently People no longer depend on such. server infrastructures any more. Due to the high investment in hardware, software, licencing fees and management costs involved in the server infrastructure. But, in case of in cloud computing services it is cheaper, quicker. Numerous email services use the cloud service to offers storage on cloud to the clients.