Which of the following is NOT tracked by your email service provider?

Engagement rate is a broad metric that encompasses various interactions beyond what an email service provider (ESP) directly tracks. While an ESP can track opens, clicks, and delivery rates, it generally doesn't have visibility into actions taken after a user leaves the email, such as website visits, purchases, or form submissions, which are crucial components of a comprehensive engagement rate. Click-through rates, delivery rates, and open rates are all standard metrics that ESPs monitor and report on as they occur within the email environment itself.