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Cisco Email Security Appliance

ESA FAQ: How do you specify multiple destination hosts with the alt-mailhost action?

Document ID: 117846

Updated: Jun 25, 2014

Contributed by Karl Young and Robert Sherwin, Cisco TAC Engineers.

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Introduction

This document describes how to specify multiple destination hosts with the alt-mailhost action on the Cisco Email Security Appliance (ESA).

Prerequisites

Requirements

Cisco recommends that you have knowledge of these topics:

  • Cisco ESA
  • AsyncOS

Components Used

The information in this document is based on all versions of AsyncOS.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

How do you specify multiple destination hosts with the alt-mailhost action?

After you apply the alt-mailhost, the ESA still uses the Simple Mail Transfer Protocol (SMTP) routes in order to determine where messages are delivered.

This means that you can specify a Fully Qualified Domain Name (FQDN) within the alt-mailhost action and then add an SMTP route entry with the specified FQDN as the receiving domain. The various destination hosts are separated by commas, and they are used in a round-robin fashion in order to deliver messages to the specified domain.

Note: In this example, the Filter action and the SMTP route entry alternate between the hosts 192.168.2.1 and 192.168.2.2.

Here is an example of the Filter action:

alt-mailhost('althost.example.com');

Here is an example of the SMTP route entry:

 Receiving Domain  Destination Host
 althost.example.com 192.168.2.1, 192.168.2.2
Updated: Jun 25, 2014
Document ID: 117846