Cisco Cisco Email Security Appliance C170

For DKIM Authentication, Cisco currently supports version 8 of the Draft Specification of 
‘Authentication-Results:’ header.

For SPF/SIDF verification, the 

spf-passed

 rule is no longer available in content filters. To maintain 

backwards compatibility, the spf-passed content filter rule will be accepted from XML configuration 
files but it will be converted to the spf-status rule with corresponding arguments. spf-passed will be 
changed to spf-status == "Pass" and NOT spf-passed to spf-status != "Pass". You can, however, still 
use the spf-passed message filter.

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