Cisco Cisco Email Security Appliance C160 Mode D'Emploi

This feature also allows host “globbing.” If you specify a partial domain, such as 

.example.com

, then any domain ending in 

example.com

 matches the entry. For 

instance, 

fred@foo.example.com

 and 

wilma@bar.example.com

 both match the 

mapping.

If a host is not found in the SMTP Routes table, an MX lookup is performed using 
DNS. The result is not re-checked against the SMTP Routes table. If the DNS MX 
entry for 

foo.domain

 is 

bar.domain

, any email sent to 

foo.domain

 is delivered to 

the host 

bar.domain

. If you create a mapping for 

bar.domain

 to some other host, 

email addressed to 

foo.domain 

is not affected. 

In other words, recursive entries are not followed. If there is an entry for 

a.domain 

to redirect to 

b.domain

, and a subsequent entry to redirect email for 

b.domain

 to 

a.domain

, a mail loop will not be created. In this case, email addressed to 

a.domain

 will be delivered to the MX host specified by 

b.domain

, and conversely 

email addressed to 

b.domain

 will be delivered to the MX host specified by 

a.domain

.

The SMTP Routes table is read from the top down for every email delivery. The 
most specific entry that matches a mapping wins. For example, if there are 
mappings for both 

host1.example.com

 and 

.example.com

 in the SMTP Routes 

table, the entry for 

host1.example.com

 will be used because it is the more specific 

entry — even if it appears after the less specific 

.example.com

 entry. Otherwise, 

the system performs a regular MX lookup on the domain of the Envelope 
Recipient.

You can also define a default SMTP route with the special keyword 

ALL

. If a 

domain does not match a previous mapping in the SMTP Routes list, it defaults to 
being redirected to the MX host specified by the 

ALL

 entry. 

When you print the SMTP Routes entries, the default SMTP route is listed as 

ALL:

. You cannot delete the default SMTP route; you may only clear any values 

entered for it.

Configure the default SMTP route via the Network > SMTP Routes page or the 

smtproutes

 command.