The most used tactical metrics in email marketing still include the ‘open rate’ and the ‘click rate’ or ‘click-through rate’ (CTR).
Just as a reminder: the ‘open rate’ is a percentage that expresses the ratio between the number of emails that are delivered to the recipient (all emails that reached the inbox) and the number of subscribers who actually opened the mail.
The CTR is the number of emails that were clicked at least once, divided by the number of delivered emails.