Click to open (CTO) rate is an email marketing metric that indicates the effectiveness of your email content and the engagement that your email campaign is generating. Click to open takes your open rate and CTR to represent how many click-throughs you get in relation to how many emails were opened.
CTO rate or CTOR is an accurate measure of your email body content's quality and the effectiveness of your content, as your aim should be to convert your email opens into clicks on your links in the email (click-through rate).
Its formula is CTO = (Unique link clicks / Unique email opens) x 100
Here, many opens and low CTR will be useless and indicate that your content and CTA are not convincing enough and do not deliver on the promise your subject line made. Meanwhile, low open rates with high CTR are also futile and may indicate that your subject line is unattractive or timing is flawed.
Hence, your job is to get both the opens and to get those people who opened your email to click your links. Using the CTO as the primary email reporting metric can help you achieve this goal.