Final answer:
The Azure Monitor feature responsible for sending an administrator an email when a VM is nearing its usage quota is Alerts. Alerts enable notifications via email when predefined conditions are encountered, assisting in efficient resource management.
Step-by-step explanation:
The Azure Monitor feature that sends an administrator an email when a VM is about to exceed its usage quota for the month is known as Alerts. This feature allows administrators to set up alert rules based on metrics or events, and when conditions specified in the rule are met, it can send notifications through various channels including email. For instance, an alert can be configured to monitor the CPU usage of a VM and send an email when the usage approaches the set threshold, helping to prevent potential overages and manage costs efficiently.