Your company has recently migrated to a cloud-based infrastructure and you are tasked with ensuring that the email system integrates seamlessly with existing cloud services. In addition to basic messaging, the requirement includes coordinating with calendar services and contact management provided by another cloud service provider. Which of the following solutions will BEST meet these requirements?
Using a Platform as a Service (PaaS) to host the email service
Implementing an SMTP Relay service
Developing a Custom Email API to interface with existing cloud services
Deploying an Infrastructure as a Service (IaaS) with a built-in email server
Software as a Service (SaaS) for email