Hi itnorm - Thanks for reaching out over Q&A Forum.
You can configure alert with Signal as Ingress Metrics.
https://video2.skills-academy.com/en-us/azure/storage/common/storage-insights-overview
https://video2.skills-academy.com/en-us/azure/azure-monitor/alerts/alerts-create-metric-alert-rule
Thereafter you can select the action group and save the alert. Based on the threshold and evaluation frequency, it shall trigger the alert.
Are you trying to configure the same but not able to select the Action Group? Or it seems to have selected the alert rule but didn't triggered mail?