The reason why a component has gone into a warning or critical status is because the component has exceeded a threshold defined. To understand what the counter is, what it means, the potential impact of exceeding the defined threshold as well as possible remediation steps, you'll probably want to include the expert knowledge that's provided for each template as part of the alert. To include this Expert Knowledge simply use the ${UserDescription} macro in your APM:Component alerts.
A component is "Down" typically because it's unable to poll. This could be due to bad credentials, unable to connect, or because that process/service is no longer running on that host. To include the error message that's shown in the Orion web interface when these issues occur as part of your email notification, you'll likely want to use the ${StatusOrErrorDescription} macro for your APM:Component alerts.