Hmm, I don't know enough to give you a confident answer yet. The knowledge sources provided do not contain specific information on how to send a Slack webhook after a successful registration with Ory. However, they do provide general information on how to trigger webhooks after successful registration. You would typically need to define a webhook action in your Ory configuration that points to your Slack webhook URL. This action would be triggered after a successful registration. The exact details of how to do this would depend on the specifics of Slack's webhook API. For more information on how to work with webhooks in Ory, you can refer to the [Ory webhook guide](https://www.ory.sh/docs/guides/integrate-with-ory-cloud-through-webhooks). For information on Slack's webhook API, you would need to refer to Slack's own documentation.