Click-to-Open Rate is a really effective mechanism that measures how interactive your email campaign is. This metric is the ratio of unique clicks on your email as a percentage of the unique opens. It measures how effective your message is in motivating recipients to click a link once they’ve opened your message. In other words, if I click 5 times in your email, it still counts as 1 click-through. If you are looking at aggregate email metrics (totaled across multiple email batches), the metrics may not be unique, as one individual may have received more than one of the same emails.
The ratio of click to open rate describes the proportion of people who have opened an email and subsequently clicked on at least one of the available links. It’s supposed to be a significant indicator of the quality of your campaign; how compelling your content is and how accurately your subject reflects the content. It can also gauge how well you are driving subscribers to take additional action within your brand/company. In addition, it can help you determine if the links in your content are positioned in a way to get interactive action.
CTOR varies primarily, based on the responsiveness of recipients receiving a mailer. There can be many reasons for this variation, including whether the mailing made it to the inbox, how the creative was presented, what was their engagement level, and more. However, there is an additional set of reasons for open rates varying: including sender whitelist status, the e-mail client platform (mobile, desktop, Web mail etc.), and recipient responsiveness. The result: open rates and CTOR vary for overlapping mails, but often independent reasons. This introduces far more complexity when comparing CTOR rates from mail to mail and campaign to campaign.