The enterprise should consider using Software as a Service (SaaS), as it allows them to subscribe to software services such as email without the need to install or maintain server hardware and software on-site. The cloud service provider handles the management, maintenance, and security of the service. While Infrastructure as a Service (IaaS) provides virtual computing resources that the enterprise would still need to manage, and Platform as a Service (PaaS) offers a development platform without pre-built software solutions like email services.