Internal addresses in Mimecast belong to?

The correct choice indicates that internal addresses in Mimecast refer specifically to the email addresses that are part of your organizational domain. This includes any email accounts that employees or members of your organization use to communicate with each other. Internal addresses are essential for effective communication within the organization and are typically configured under the company’s own domain, ensuring that message routing and handling are secure and efficient.

In this context, the other choices do not apply. External partners might use different domains or email addresses not managed under your organization’s Mimecast setup. Public domains refer to general or widely available email addresses, such as those from free email providers, which again are not associated with internal operations. Cloud services may involve third-party applications or services, but they do not define the internal communication structure of your organization. Thus, the specificity of internal addresses as belonging to your own organization makes this answer the most appropriate.