Script enviador de Mail en elixir

mailer.exs

Mix.install([:swoosh, :hackney, :mail])

Application.put_env(:myapp, Prueba.Mailer, adapter: Swoosh.Adapters.Gmail, access_token: {:system, "GMAIL_API_ACCESS_TOKEN"})
Application.put_env(:myapp, :email_conf, to_mail: "[email protected]", from_mail: "[email protected]")

defmodule Prueba.Mailer do
  use Swoosh.Mailer, otp_app: :myapp
end

defmodule Prueba.Enviador do
    import Swoosh.Email

    def enviar do
        email_conf = Application.get_env(:myapp, :email_conf)
        IO.puts(email_conf[:to_mail])
        email = new()
            |> to({"Prueba", email_conf[:to_mail] })
            |> from({"Prueba", email_conf[:from_mail] })
            |> subject("Holaa!")
            |> html_body("<h1>Hello Prueba</h1>")
            |> text_body("Hello Prueba\n")

        Prueba.Mailer.deliver(email)
    end
end

Prueba.Enviador.enviar