Which of the following is NOT a system variable usable in an email alert?

In the context of email alerts in Tenable Security Center, system variables are placeholders that dynamically pull in relevant information when an email alert is generated. Each variable has a specific purpose, allowing users to receive tailored notifications based on the alert's context.

The correct choice, which is not a valid system variable for email alerts, is %reportFrequency%. This particular variable does not exist within the system because email alerts are designed primarily to provide immediate notification of specific alerts or events, rather than to convey information regarding how often a report is generated.

In contrast, variables like %alertID%, %triggerName%, and %url% are valid options that enhance the effectiveness of the alerts. %alertID% provides the unique identifier for the alert, %triggerName% indicates the name of the specific trigger that caused the alert, and %url% typically links to additional information or the relevant section of the Security Center dashboard. By using these variables, the alert emails are both informative and actionable, assisting users in promptly addressing security issues.