post https://apptracking.retailrocket.net/2.0/emailClick
Email content click event. Should be called when a user navigates out of email.
All links in the email contain a MailTrackingId GET parameter with a unique value for each email. Each time when a user navigates to the website from email, URL will contain the MailTrackingId parameter, its value should be passed to the request body of this method.