Provide a way for users to resubscribe
The %unsubscribe_url% tag can be used to create a link to the Mailgun unsubscribe page, but once a user has unsubscribed they can't resubscribe themselves later. They might have unsubscribed in error, or changed their mind, but there's no way for them to opt back in themselves.
Ideally you'd have a "Manage my subscription" page that could be linked to via a tag like the %unsubscribe_url% tag, where a user can either unsubscribe or resubscribe themselves.
Eduardo Messuti commented
I'd also like to see this feature added +1