User Guide

24-17
AsyncOS 9.1.2 for Cisco Email Security Appliances User Guide
Chapter 24 Configuring Routing and Delivery Features
Configuring Masquerading
Note The Masquerading feature is configured on a per-listener basis, as opposed to the Alias Tables
functionality, which is configured for the entire system.
Note A listener checks the masquerading table for matches and modifies the recipients while the message is
in the work queue, immediately after LDAP recipient acceptance queries and before LDAP routing
queries. See the “Understanding the Email Pipeline” chapter.
The Masquerading feature actually rewrites addresses for the Envelope Sender and the To:, From:, and
CC: fields of the email that has been received. You can specify different masquerading parameters for
each listener you create in one of two ways:
• via a static table of mappings you create
• via an LDAP query.
This section discusses the static table method. The table format is forward-compatible with the
/etc/mail/genericstable feature of a sendmail configuration on some Unix systems. See Chapter 25,
“LDAP Queries” for more information on LDAP masquerading queries.
Related Topics
• Masquerading and altsrchost, page 24-17
Masquerading and altsrchost
Generally, the masquerading feature rewrites the Envelope Sender, and any subsequent actions to be
performed on the message will be “triggered” from the masqueraded address. However, when you run
the
altscrchost command from the CLI, the altsrchost mappings are triggered from the original address
(and not the modified, masqueraded address).
For more information, see Configuring Mail Gateways for all Hosted Domains Using Virtual Gateway™
Technology, page 24-59 and Review: Email Pipeline, page 24-73.
Related Topics
• Configuring Static Masquerading Tables, page 24-17
• Sample Masquerading Table for a Private Listener, page 24-19
• Importing a Masquerading Table, page 24-19
• Example Masquerading, page 24-19
Configuring Static Masquerading Tables
You configure the static masquerading table of mappings by using the edit -> masquerade
subcommand of the
listenerconfig command. Alternatively, you can import a file containing the
mappings. See Importing a Masquerading Table, page 24-19. The subcommand creates and maintains a
table that maps input addresses, usernames, and domains to new addresses and domains. See Chapter 25,
“LDAP Queries” for more information on LDAP masquerading queries.
When messages are injected into the system, the table is consulted, and the message is rewritten if a
match in the header is found.