   gen_smtp_major =
     if Code.ensure_loaded?(:gen_smtp_application) do
       Application.load(:gen_smtp)
-      :gen_smtp |> Application.spec(:vsn) |> to_string() |> Version.parse!() |> Map.get(:major)
+
+      :gen_smtp
+      |> Application.spec(:vsn)
+      |> to_string()
+      |> Version.parse!()
+      |> Map.get(:major)
     else
       0
     end

  end

  defp prepare_part(_subtype, nil, _config), do: nil

  defp prepare_part(subtype, content, config) do
    subtype_string = to_string(subtype)

     [
       {"Content-Type", "text/#{subtype_string}; charset=\"utf-8\""},
       {"Content-Transfer-Encoding", transfer_encoding}
     ], @content_params, content}
  end

  defp add_content_type_header(headers, value) do
