Dynamic email recipients in a flow

Hello!

I am triggering an event using the /event API from my backend system any time an appointment is booked on our website. My use case is to email the person that booked an appointment (the customer) and also email the person that the customer is booking with (the provider). There is no issue sending the first email because I am setting the profile.data.id value. I am also sending the email address for the provider via the attributes.properties.providerEmail. I can’t seem to find a way to access this variable in either notifications or email. 

Here is my post body:

{
  "data": {
    "type": "event",
    "attributes": {
      "properties": {
        "providerEmail":"test@test.com",
      },
      "time": "2023-09-28T24:31:52",
      "metric": {
        "data": {
          "type": "metric",
          "attributes": {
            "name": "Booked Appointment"
          }
        }
      },
      "profile": {
        "data": {
          "type": "profile",
          "id": "1234"
        }
      }
    }
  }
}