A Symantec Brightmail Gateway Alert Notification is notifying you that a hardware component has an unknown problem. What does this mean? 

The alert notification looks like this:

Symantec Brightmail Gateway Alert Notification for
======================= ALERT NOTIFICATION ================================
The following hardware components are not responding/working:

Host Component Problem
---------------------------------------------------------------------------
DISK Unknown
FAN Unknown
POWER SUPPLY Unknown
---------------------------------------------------------------------------

You may also see log entries similar to the ones shown below in messages log file:

2009 Dec 10 12:25:45 (crit) SMS::Hardware: Unable to determine RAID array state after 10 retries. RAID array in Unknown state
...
2009 Dec 10 12:31:16 (crit) SMS::Hardware: Unable to determine BATTERY charge after 10 retries. BATTERY in Unknown state

This issue can occur due to the following conditions:

1. SNMP monitoring service is hanging or stopped
2. CPU utilization is extremely high

If the issue is cause by condition #1, then you will see the alerts at regular intervals. Whereas, if the issue is due to condition #2, you will see the alerts intermittently.

The monitoring service checks the status of hardware components periodically using internal SNMP queries. When the hardware monitoring service can not complete the monitoring task due to one or more of the above conditions, it returns an "Unknown" status and triggers the alert, if configured.

Depending on the condition causing the issue, please follow the steps below to resolve the issue:

1. If the issue is caused by condition #1, then restart the SNMP service to resolve the issue. From the Control Center, clicking Save on Administration > SNMP page (without changing anything) will restart the SNMP service. You can also restart the SNMP service from the CLI using the following command:

service snmpd restart

Please note that in rare cases the SNMP service may not restart properly and you will have to reboot the appliance to resolve the issue.

2. If the issue is caused by condition #2, then either the appliance you have is not sufficient to handle mail load for your environment or you are experiencing message processing issues. For optimizing the performance of existing hardware, please consult the knowledge base article under the References section below.

For message processing issues, please contact Technical Support.

References:
Symantec Brightmail Gateway (SBG) - Best Practices: Performance
http://www.symantec.com/docs/TECH89920