Admins track various metrics to evaluate the success of their email marketing campaigns. Key metrics include the open rate, click-through rate (CTR), conversion rate, bounce rate, and unsubscribe rate. Open rate measures how many recipients opened the email, while CTR indicates how many clicked on links within the email. Conversion rate tracks the percentage of recipients who took a desired action, such as making a purchase, while bounce rate and unsubscribe rate provide insights into the health of the email list.