The email / newsletter click-through rate refers to the percentage of recipients who click on a link or call-to-action within an email or newsletter. It is a measure of the effectiveness of an email or newsletter in driving engagement and directing readers to a desired destination, such as a website, landing page, or product page. A higher click-through rate indicates that the email or newsletter successfully captured the attention of its audience and enticed them to take action. This metric is commonly used in email marketing and is a key indicator of the success of a campaign.