   end
 
   defp prepare_part(_subtype, nil, _config), do: nil
+
+  @content_params if(gen_smtp_major >= 1,
+                    do: %{
+                      content_type_params: [{"charset", "utf-8"}],
+                      disposition: "inline",
+                      disposition_params: []
+                    },
+                    else: [
+                      {"content-type-params", [{"charset", "utf-8"}]},
+                      {"disposition", "inline"},
+                      {"disposition-params", []}
+                    ]
+                  )
 
   defp prepare_part(subtype, content, config) do
     subtype_string = to_string(subtype)

          html_part

        {text_part, html_part} ->
          {"multipart", "alternative", [], [], [text_part, html_part]}
      end

    attachment_parts = Enum.map(attachments, &prepare_attachment(&1))

  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)
    else
      0
    end
