The system automatically adds a list-unsubscribe header to your sent campaigns.
To check, you can send an email to your Gmail from our system (or check a previous received email from the system).
Once opened, click the drop down next to the recipient name: (it will say "show details" if hovered over).
Note the unsubscribe option that is linked:
We don't recommend actually unsubscribing from your own mailing list unless you are using a purely test email.