CTOR, also known as click-to-open rate, is a metric used to evaluate how effective an email campaign is. CTOR is calculated by dividing the number of people who click on a link in an email by the number of people who open the email.For example, if 100 people open an email and 10 of them click on a link, the CTOR would be 10%. CTOR can be a valuable metric because it allows you to see how many of the people who were exposed to your email campaign actually took action. This can be helpful in evaluating the effectiveness of your email content and subject line. Additionally, CTOR can be used to compare the performance of different email campaigns. For example, you could compare the CTOR of two different emails to see which one was more successful in getting people to take action. CTOR is just one metric that can be used to evaluate an email campaign, but it can be a helpful tool in understanding how your audience interacts with your emails.