curl --request POST \
  --url https://api.paubox.net/v1/orca/{username}/subscribers \
  --header 'Content-Type: application/json' \
  --header 'authorization: <api-key>' \
  --data '
{
  "subscriber": {
    "email": "test@example.com",
    "first_name": "test",
    "last_name": "example"
  }
}
'

{
  "data": {
    "id": "<string>",
    "type": "subscriber",
    "attributes": {
      "email": "jsmith@example.com",
      "unsubscribed": true,
      "first_name": "<string>",
      "last_name": "<string>"
    }
  }
}