It is my understanding that the only way to track Unsubscribe volume and % in email metrics is to use the official Unsubscribe link: {{email.unsubscribe_link}}

We want to use a form method, such that when someone clicks our "Unsubscribe" link in the bottom of an email, it takes them to a landing page where it asks them to fill in their email and submit, and then we have a Workflow to mark “DND Email Channel = True” when they submit said form.

This is to:

1) Assure the user really intended to unsubscribe from all communications when they hit the unsubscribe link vs unsubscribe from a particular type of email (which we can verify with them via the copy on the landing page)

2) Assure the user enters the email address they actually intend to unsubscribe

However, right now we are forced to choose between using our method that implements the best practices we would like to deploy, and actually tracking Unsubscribes in each our our email's metrics.