You can configure individual and global threshold settings for metrics including application pools and sites in your IIS application monitor.
Please follow the below steps to set threshold at a global level:
- Log in and navigate to Home > Monitors > click on the icon against the IIS monitor > Select Edit

- Under Configuration Profiles, click on the pencil icon against Threshold and availability

- Under Threshold Configuration > set Yes for Notify when Site/Application Pool is down

- Save your preferences
Please follow the below steps to set threshold at an individual level:
- Log in and navigate to Home > Monitors > click on the icon against the IIS monitor > Select Edit
- Under Configuration Profiles, click on the pencil icon against Threshold and availability
- Under Threshold Configuration > set No for Notify when Site/Application Pool is down

- Now, go to Home > Monitors > Select the IIS server to be configured
- Go to Sites or Application Pools tab
- Against the Site/Application Pool to be configured, click the pencil icon under Action

- Set Yes for Notify when Site/Application Pool is down

- Save the changes
Note: This is to be performed only for the Sites/Application Pools for which the user wants to be notified during trouble or down