Which tool is used to verify a mailbox in a Windows environment?

The Exchange Management Console is the appropriate tool for verifying a mailbox in a Windows environment, particularly when working with Microsoft Exchange Server. This console provides administrators with a comprehensive interface to manage Exchange settings and monitor mailbox attributes, allowing for tasks such as confirming a mailbox's existence, checking its status, and modifying settings if necessary.

In contrast, the other tools mentioned serve different purposes; for instance, Task Manager is primarily focused on monitoring processes and system performance rather than managing mailboxes. Active Directory Users and Computers is used for managing user accounts and groups but does not offer the extensive functionality specific to mailboxes that the Exchange Management Console does. System Configuration is mainly utilized for managing startup settings and system services, thus falling outside the scope of mailbox verification. Therefore, the Exchange Management Console stands out as the dedicated tool for this specific administrative task.