An engineer is configuring Cisco Secure Email Gateway and needs to enable a separated email transfer flow from the Internet and from the LAN. Which deployment mode must be used to accomplish this…

Single interface mode processes both external and internal email traffic through a single network interface, which does not provide a separated email transfer flow.

Multi-context mode is a feature found in firewalls (like Cisco ASA) that allows multiple virtual firewalls to run on a single physical device, not a deployment mode for an email gateway to separate mail flows.

Transparent mode, often used for firewalls, allows a device to operate without an IP address in the network path, but it does not specifically define how an email gateway separates internet and LAN mail flows as 'two-interface' mode does.

In a two-interface deployment mode for the Cisco Secure Email Gateway, one network interface is dedicated to handling external (Internet-facing) email traffic, while the second interface handles internal (LAN-facing) email traffic, allowing for distinct security policies, scanning, and routing rules to be applied to each flow.