We’re currently using the client credentials grant to be able to get an access_token to use for the SendGrid Event Webhook. The issue we’re having is they dont accept the Audience param as input.
It turns out we aren’t able to support this use case at the moment. There isn’t a way to get around the fact that you can’t add an audience to the webhook call, and Auth0 requires the audience for the request to be valid.
This issue is in our backlog, but I don’t have an ETA on when/if it will be resolved.
I think it would be helpful if you created a Feature Request for this. These requests help us track demand.