Cisco Cisco Email Security Appliance C390

In previous versions of AsyncOS, AsyncOS upgrades, PXE Engine updates, and 
McAfee Anti-Virus definitions could use a different update server than services 
such as IronPort Anti-Spam rules and Feature Key rules. In AsyncOS 7.5, 
AsyncOS upgrades use the same update server as all of the service updates, 
whether it’s an IronPort update server or a local update server. This will prevent 
you from using a local server for AsyncOS upgrades and an IronPort update server 
for all other service updates unless you configure the appliance to use a manifest 
on a local appliance to perform an AsyncOS upgrade and the re-configure the 
appliance to use an IronPort update server for the other services after the upgrade 
is complete.

SNMP does not start when you boot the appliance after upgrading to AsyncOS 
7.5. Use snmpconfig -> setup and then commit to enable it.

If you are monitoring Email Security appliances using SNMP, the number of open 
files will increase to around 2500 after upgrading the appliance to AsyncOS 7.5. 

For DKIM Authentication, IronPort 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.