What type of messages can be utilized to populate an Internal Directory?

An Internal Directory in the context of Mimecast is populated with messages that are specifically designed to be archived or journaled, capturing all relevant information about communications within an organization. Journaled messages are comprehensive records of emails that include both the content and metadata necessary for creating an accurate representation of communication patterns, which is essential for compliance, auditing, and security purposes.

Journaled messages allow for the effective organization and retrieval of data for internal use, enabling organizations to maintain a well-structured Internal Directory. This structured approach ensures that all messages are appropriately recorded and accessible for future reference.

The other message types, such as plain text and HTML, are formats for composing messages rather than methods for archiving and organizing them. Delivery routes, while they refer to the path taken by messages through the email system, do not create or populate an Internal Directory. Thus, the use of journaled messages stands out as the correct choice for populating an Internal Directory effectively.