Cisco Cisco Email Security Appliance C680

Cisco does not generally support the backward compatibility of configuration files with previous major 
releases. Minor release support is provided. Configuration files from previous versions may work with 
later releases; however, they may require modification to load. Check with Cisco Customer Support if 
you have any questions about configuration file support. 

When you configure AsyncOS to use received headers, you can specify that the header reflects one of 
the following hostnames:

The hostname of the Virtual Gateway used for delivering the message

The hostname of the interface the message is received on

You specify the hostname from the CLI command listenerconfig-> setup. You cannot configure the 
hostname from the web interface.

If you configure the received header to display the hostname of the interface the message is received on, 
a strip-header filter action configured to strip received headers will strip the received header inserted 
by AsyncOS.

The AsyncOS appliance checks for and applies feature keys at one minute intervals. Therefore, when 
you add a feature key, it may take up to a minute to view the changes.

From AsyncOS 8.5.x for Email, Email Security appliance will enter resource conservation mode when 
the RAM utilization exceeds 45% and the allowed injection rate is gradually decreased as RAM 
utilization approaches 60%. Appliances with large memory utilization, especially with large system 
quarantine, can enter resource conservation immediately after upgrading to AsyncOS 8.5.x for Email. 
To avoid this scenario, make sure that you reduce the system quarantine to a few thousand messages 
before upgrading.

Review the 

Use the following instructions to upgrade your Email Security appliance.

Save the XML configuration file off the appliance. 

If you are using the Safelist/Blocklist feature, export the Safelist/Blocklist database off the appliance. 

Suspend all listeners.

Wait for the queue to empty.