Simple proxy to route a Mailgun webhook call to a Slack webhook. Deploy free to heroku with one click.
Your webhook URL will be: https://{yourapp}.herokuapp.com/api/mailgun.
This proxy has nothing to do with the Mailgun addon for other Heroku apps. It is purley a simple proxy so you can be notified of failed emails for any Mailgun account (also regular Mailgun accounts, which are not Heroku addons).