Reference: https://www.cisco.com/c/en/us/td/docs/security/esa/esa12-0/user_guide/b_ESA_Admin_Guide_12_0/b_ESA_Ad Therefore Outbreak filters can be used to block emails from bad mail servers.Web servers and email gateways are generally located in the DMZ soNote: The recipient access table (RAT), not to be confused with remote-access Trojan (also RAT), is a Cisco ESA term that defines which recipients are accepted by a public listener.