The correct answer is B. To allow users to manage their quarantined emails and email preferences. Proofpoint end-user materials describe the quarantine web experience as the place where users can view quarantined messages, release them when permitted, and manage sender or digest-related preferences. End-user guides and operational help pages consistently frame the interface around quarantine management and personal email-security settings, not full administrative control.

This matches the purpose taught in the Threat Protection Administrator course. The End User Web Interface is designed to give users limited self-service capability so they can review held mail and adjust certain personal settings without requiring an administrator for every routine action. That is very different from automatically blocking all incoming mail, configuring network-firewall policy, or serving as the primary mechanism for sending encrypted external messages. Those options describe other technologies or broader administrative capabilities, not the core function of the End User Web Interface.

In practice, this interface helps reduce administrative burden by letting users handle everyday quarantine tasks themselves while keeping more sensitive platform-wide controls in administrator hands. Therefore, the verified and course-aligned answer is B.