Cisco Cisco Email Security Appliance C160 Mode D'Emploi

In this query, the 

{d}

 represents the domain part of the recipient address, and the SMTP Call-Ahead 

Server Attribute returns the values for the call-ahead servers and the port that should be used for the 
query: smtp2.mydomain.com, smtp3.mydomain.com on port 9025. 

This example shows just one way to configure a query that enables you to use the LDAP routing query 
to direct SMTP call-ahead queries to the correct SMTP servers. You are not required to use the query 
string or specific LDAP attributes described in this example. 

When routing an SMTP call-ahead query, AsyncOS checks for information in the following order:

If there is no LDAP routing query or no SMTP Routes configured for the domain, the result of preceding 
state is passed to next stage. In any case where there is no SMTP Route present, a DNS lookup is 
performed.

When you use an LDAP Routing query for an SMTP call-ahead query and you also have SMTP routes 
configured, the routing behavior depends upon the values returned by the routing query.

If the LDAP routing query returns a single hostname without a port, the SMTP call-ahead query 
applies SMTP routes. If the SMTP routes only lists the destination host as the hostname, a DNS 
lookup is performed to obtain the IP address of the SMTP server. 

Checks the domain name.

Checks for LDAP Routing queries.

Checks for SMTP Routes. 

Performs a DNS Lookup (First an MX Lookup is 
performed, followed by an A lookup).