What is the process of moving mailboxes between different Active Directory forests called?

The process of moving mailboxes between different Active Directory forests is indeed referred to as "Cross-forest mailbox moves." This terminology specifically describes the transfer of user mailboxes from one Active Directory forest to another, which can involve complex considerations such as identity synchronization, permissions, and ensuring that the mailboxes maintain their data integrity during the transition.

Cross-forest mailbox moves are significant in larger organizations that may have multiple Active Directory forests due to acquisitions, mergers, or organizational restructuring. Understanding this term helps professionals manage mailbox migrations effectively while ensuring that communication and access are maintained between the different environments.

Other terms in the answer options may imply related concepts but do not accurately represent the specific process defined in the question. For instance, "Inter-forest mailbox migration" could suggest a similar concept but is not the standardized term recognized in Microsoft Exchange documentation. "Forest-to-forest mailbox transfer" might describe the transfer itself, yet it lacks the precision of "cross-forest mailbox moves," which is the recognized terminology. Lastly, "Active Directory mailbox transfer" is too broad and does not capture the uniqueness of the cross-forest context.

By understanding the correct terminology, IT professionals can communicate more effectively about their processes and work more efficiently within Microsoft Exchange environments.