Cisco Cisco Email Security Appliance C160 Guía Del Usuario
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Cisco AsyncOS 9.1 for Email User Guide
Chapter 5 Configuring the Gateway to Receive Email
Listening for Connection Requests by Creating a Listener via the GUI
Step 5
(Optional) Configure advanced settings for customizing the behavior of the listener as defined in the
following table.
following table.
Step 6
(Optional) Configure settings for controlling LDAP queries associated with this listener as defined in the
following table.
following table.
Use these settings to enable LDAP queries on the listener. You must create the LDAP query first, before
using this option. Each type of query has a separate subsection to configure. Click the type of query to
expand the subsection.
using this option. Each type of query has a separate subsection to configure. Click the type of query to
expand the subsection.
Setting
Description
Maximum Concurrent
Connections
Connections
The maximum number of connections allowed.
TCP Listen Queue Size
The backlog of connections that AsyncOS will manage before the SMTP
server accepts them.
server accepts them.
CR and LF Handling
Choose how to handle messages that contain bare CR (carriage return) and
LF (line feed) characters.
LF (line feed) characters.
•
Clean. Allows the message, but converts bare CR and LF characters to
CRLF characters.
CRLF characters.
•
Reject. Rejects the message.
•
Allow. Allows the message.
Add Received Header
Add a received header to all received email. A listener also modifies email
that it relays by adding a Received: header on each message. If you do not
want to include the Received: header, you can disable it using this option.
that it relays by adding a Received: header on each message. If you do not
want to include the Received: header, you can disable it using this option.
Note
The Received: header is not added to the message within the work
queue processing. Rather, it is added when the message is enqueued
for delivery.
queue processing. Rather, it is added when the message is enqueued
for delivery.
Disabling the received header is a way to ensure that your network’s
topology is not exposed by revealing the IP addresses or hostnames of
internal servers on any messages traveling outside your infrastructure.
Please use caution when disabling the received header.
topology is not exposed by revealing the IP addresses or hostnames of
internal servers on any messages traveling outside your infrastructure.
Please use caution when disabling the received header.
Use SenderBase IP
Profiling
Profiling
Choose whether or not to enable SenderBase IP Profiling and configure the
following settings:
following settings:
•
Timeout for Queries. Define how long the appliance caches
information queried from the SenderBase Reputation Service.
information queried from the SenderBase Reputation Service.
•
SenderBase Timeout per Connection. Define how long the appliance
caches SenderBase information per SMTP connection.
caches SenderBase information per SMTP connection.