Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

 provides an overview of the various features used for rewriting sender and recipient email 

addresses.

Alias tables provide a mechanism to redirect messages to one or more recipients. You can construct a 
mapping table of aliases to usernames and other aliases in a similar fashion to the 

/etc/mail/aliases

 

feature of a sendmail configuration on some Unix systems. 

When the Envelope Recipient (also known as the Envelope To, or 

RCPT TO

) of an email accepted by a 

listener matches an alias as defined in an alias table, the Envelope Recipient address of the email will be 
rewritten. 

A listener checks the alias table and modifies the recipients after checking the RAT and before message 
filters. See the “Understanding the Email Pipeline” chapter. 

The Alias Table functionality actually rewrites the Envelope Recipient of the email. This is different than 
the 

smtproutes

 command (see 

), which does not rewrite the 

Envelope Recipient of the email, but instead simply reroutes the email to specified domains.

Alias tables are defined in sections as follows: each section is headed by a domain context, which is a 
list of domains that the section is relevant to, followed by a list of maps. 

*@anydomain

user@domain

Alias Tables (see 

)

Envelope Recipients only

Applied globally

Maps aliases to email 
addresses or other aliases

*@olddomain

*@newdomain

Domain Mapping (see 

Envelope Recipients only

Applied per listener

*@olddomain

*@newdomain

Masquerading (see 

Envelope Sender and the 
To:, From:, and/or CC: 
headers

Applied per listener