Click to open rate (CTOR) is an email marketing metric used to assess the effectiveness of email content. It compares the number of people who clicked on an email link (click through rate, or CTR) to the total number of people who opened that email (email open rate). Generally speaking, the higher an email’s CTOR is, the more engaging and appealing the content is perceived to be for subscribers. These insights can be used to assess the health of a company’s email campaigns and its email marketing strategy.