IronPort - advanced configuration guide

Default Delivery Limits
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Cisco IronPort AsyncOS 7.6 for Email Advanced Configuration Guide
Chapter 2 Configuring Routing and Delivery Features
Each outbound destination domain has its own outbound queue. Therefore, each domain has a separate
set of concurrency limits as specified in the Destination Controls table. Further, each unique domain not
listed specifically in the Destination Controls table uses another set of the “Default” limits as set in the
table.
Working with Destination Controls
Use the Mail Policies > Destination Controls page in the GUI or the destconfig command in the CLI to
create, edit, and delete Destination Control entries.
Controlling the Version of Internet Protocol Addresses
You can configure which version of Internet Protocol addresses to use for the connection to a domain.
The Email Security appliance uses both Internet Protocol version 4 (IPv4) and Internet Protocol version
(IPv6). You can configure a listener on the appliance to use one version of the protocol or both.
If the “Required” setting for either IPv4 or IPv6 is specified, the Cisco IronPort appliance will negotation
a connection to the domain using an address of the specified version. If the domain doesn’t use that IP
address version, no email will be sent. If the “Preferred” setting for either IPv4 or IPv6 is specified, the
Cisco IronPort appliance will first attempt to negotation a connection to the domain using an address of
the specified version then fall back to the other if the first is not reachable.
Controlling the Number of Connections, Messages, and Recipients to a Domain
You may want to limit how your appliance will deliver email to avoid overwhelming remote hosts or your
own internal groupware servers with email from your appliance.
For each domain, you can assign a maximum number of connections, outbound messages, and recipients
that will never be exceeded by the system in a given time period. This “good neighbor” table is defined
through the Destination Controls feature (Mail Policies > Destination Controls or the destconfig
command — previously the setgoodtable command). You can specify the domain name using the
following syntax:
domain.com
or
.domain.com
This syntax enables AsyncOS to specify destination controls for sub-domains such as
sample.server.domain.com without entering each full subdomain address individually.
For connections, messages, and recipients, you set whether the limits you define are enforced for each
Virtual Gateway address, or for the entire system. (Virtual Gateway address limits control the number of
concurrent connections per IP interface. System-wide limits control the total number of connections the
Cisco IronPort appliance will allow.)
You also set whether the limits you define are enforced for each MX record of the specified domain, or
for the entire domain. (Many domains have multiple MX records defined for accepting email.)
Note The current system default is 500 connections per domain and 50 messages per connection.
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