Cisco Cisco Content Security Management Appliance M1070 Guida Utente

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 using the Management Appliance > Network > SMTP Routes page 
or the smtproutes command.

The Email Security appliance routes mail to local domains to hosts specified using the Management 
Appliance > Network > SMTP Routes page (or the smtproutes command). This feature is similar to 
the sendmail mailer table feature. (The SMTP Routes page and smtproutes command are an expansion 
of the AsyncOS 2.0 Domain Redirect feature.):

Use the Management Appliance > Network > SMTP Routes page (or the smtproutes command) to 
construct routes. When you create a new route, you first specify the domain or partial domain for which 
you want to create a permanent route. You then specify destination hosts. Destination hosts can be 
entered as fully-qualified hostnames or as IP addresses. You can also specify a a special destination host 
of 

/dev/null

 to drop the messages that match the entry. (So, in effect, specifying 

/dev/null

 for the 

default route is will ensure that no mail received by the appliance is ever delivered.) 

Multiple destination host entries can contain both fully-qualified hostnames and IP addresses. Separate 
multiple entries with commas. 

If one or more of the hosts are not responding, messages will be delivered to one of the reachable hosts. 
If all the configured hosts are not responding, mail will be queued for that host (does not fail over to 
using MX records).