It is the rate that shows how much of the e-mails that businesses send to their recipients and reach the recipients are delivered and clicked.
For example, out of 100 e-mails you send, 95 of them are delivered to your target audience, but they may not be clicked by the recipient. Clicks Per delivered shows what percentage of those 95 e-mails was clicked by the recipients. This metric also allows you to measure how successful your campaigns, announcements and notifications are.