@spec deliver(any()) :: no_return()

@spec deliver_now(Bamboo.Email.t(), Enum.t()) ::
  {:ok, Bamboo.Email.t()}
  | {:ok, Bamboo.Email.t(), any()}
  | {:error, Exception.t() | String.t()}

@spec deliver_now!(Bamboo.Email.t(), Enum.t()) ::
  Bamboo.Email.t() | {Bamboo.Email.t(), any()}

@spec send(Bamboo.Email.t()) ::
  :ok | {:error, :hard_bounce} | {:error, :unknown_error}