CPU usage alerts can be configured from the old-school SmartView Monitor application, from the Gateway Status screen, right click any gateway and select Configure Thresholds, then Edit Global Settings:
The easiest way to get memory alerts is to ensure Aggressive Aging is configured, and set it to alert. The default threshold for alerting is 80% memory utilization which can be adjusted on the Advanced screen; because most non-VSX firewalls these days are set to automatically increase the connection table size, Aggressive Aging only triggers on excessive memory utilization (sk122154: How is Aggressive Aging enforced when Concurrent Connections Capacity Limit is calculated ...😞
How and where the alerts are sent is configured from the Global properties, see here for an example: sk25941: Configuring 'Mail Alerts' using 'internal_sendmail' command
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