Email delivery is measured using several key metrics:
Delivery Rate - the percentage of emails that successfully reached the recipient's inbox. Bounce Rate - the percentage of emails that could not be delivered. This is further divided into hard bounces (permanent delivery failures) and soft bounces (temporary issues). Open Rate - the percentage of delivered emails that are opened by the recipient. Click-Through Rate (CTR) - the percentage of recipients who clicked on one or more links in the email.