diff --git a/lib/bamboo/adapters/message/content.ex b/lib/bamboo/adapters/message/content.ex
index d76f142..f8dce24 100644
--- a/lib/bamboo/adapters/message/content.ex
+++ b/lib/bamboo/adapters/message/content.ex
@@ -4,6 +4,8 @@ defmodule BambooSes.Message.Content do
   Depending on email it can generate simple, raw or template content.
   """
 
+  alias BambooSes.Encoding
+
   @type t :: %__MODULE__{
           Template:
             %{
@@ -78,8 +80,8 @@ defmodule BambooSes.Message.Content do
        when is_map(template_params),
        do: %__MODULE__{Template: template_params}
 
-  defp build_content(_email, _template_params, subject, text, html, [], []),
-    do: build_simple_content(subject, text, html)
+  defp build_content(_email, _template_params, subject, text, html, headers, []),
+    do: build_simple_content(subject, text, html, headers)
 
   defp build_content(email, _template_params, _subject, _text, _html, _headers, _attachments) do
     raw_data =
@@ -94,18 +96,26 @@ defmodule BambooSes.Message.Content do
     }
   end
 
-  defp build_simple_content(subject, text, html) do
+  defp build_simple_content(subject, text, html, headers) do
     %__MODULE__{
       Simple: %{
         Subject: %{
           Charset: "UTF-8",
           Data: subject
         },
-        Body: build_simple_body(text, html)
+        Body: build_simple_body(text, html),
+        Headers: build_headers(headers)
       }
     }
   end
 
+  defp build_headers(headers) do
+    Enum.map(
+      headers,
+      fn {name, value} -> %{"Name" => name, "Value" => Encoding.maybe_rfc1342_encode(value)} end
+    )
+  end
+
   defp build_simple_body(text, html) do
     %{}
     |> put_text(text)
diff --git a/test/lib/bamboo/adapters/content_raw_test.exs b/test/lib/bamboo/adapters/content_raw_test.exs
index ed2cae9..bc1aaae 100644
--- a/test/lib/bamboo/adapters/content_raw_test.exs
+++ b/test/lib/bamboo/adapters/content_raw_test.exs
@@ -7,6 +7,7 @@ defmodule BambooSes.ContentRawTest do
   test "generates raw content when there is a header" do
     content =
       TestHelpers.new_email()
+      |> Email.put_attachment(Path.join(__DIR__, "../../../support/invoice.pdf"))
       |> Email.put_header("X-Custom-Header", "custom-header-value")
       |> Content.build_from_bamboo_email()
 
@@ -18,12 +19,7 @@ defmodule BambooSes.ContentRawTest do
 
     parsed_content = EmailParser.parse(raw_data)
 
-    raw_data
-    |> EmailParser.parse()
-
     assert EmailParser.subject(parsed_content) == "Welcome to the app."
-    assert EmailParser.text(parsed_content) == "Thanks for joining!"
-    assert EmailParser.html(parsed_content) == "<strong>Thanks for joining!</strong>"
     assert header = EmailParser.header(parsed_content, "X-Custom-Header")
     assert header == "custom-header-value"
   end
@@ -100,6 +96,7 @@ defmodule BambooSes.ContentRawTest do
 
     content =
       TestHelpers.new_email()
+      |> Email.put_attachment(Path.join(__DIR__, "../../../support/invoice.pdf"))
       |> Email.put_header("X-Custom-Header", custom_header)
       |> Content.build_from_bamboo_email()
 
diff --git a/test/lib/bamboo/adapters/content_simple_test.exs b/test/lib/bamboo/adapters/content_simple_test.exs
index f7abe85..61810ff 100644
--- a/test/lib/bamboo/adapters/content_simple_test.exs
+++ b/test/lib/bamboo/adapters/content_simple_test.exs
@@ -15,7 +15,36 @@ defmodule BambooSes.ContentSimpleTest do
                  Html: %{Charset: "UTF-8", Data: "<strong>Thanks for joining!</strong>"},
                  Text: %{Charset: "UTF-8", Data: "Thanks for joining!"}
                },
-               Subject: %{Charset: "UTF-8", Data: "Welcome to the app."}
+               Subject: %{Charset: "UTF-8", Data: "Welcome to the app."},
+               Headers: []
+             }
+           }
+  end
+
+  test "generates simple content with headers" do
+    content =
+      new_email()
+      |> Email.put_header("X-Custom-Header", "custom-value")
+      |> Email.put_header("X-Custom-Non-Ascii-Header", "𐰴𐰀𐰽𐱄𐰆𐰢")
+      |> Content.build_from_bamboo_email()
+
+    assert content == %Content{
+             Simple: %{
+               Body: %{
+                 Html: %{Charset: "UTF-8", Data: "<strong>Thanks for joining!</strong>"},
+                 Text: %{Charset: "UTF-8", Data: "Thanks for joining!"}
+               },
+               Subject: %{Charset: "UTF-8", Data: "Welcome to the app."},
+               Headers: [
+                 %{
+                   "Name" => "X-Custom-Header",
+                   "Value" => "custom-value"
+                 },
+                 %{
+                   "Name" => "X-Custom-Non-Ascii-Header",
+                   "Value" => "=?utf-8?B?8JCwtPCQsIDwkLC98JCxhPCQsIbwkLCi?="
+                 }
+               ]
              }
            }
   end
@@ -32,7 +61,8 @@ defmodule BambooSes.ContentSimpleTest do
                  Html: %{Charset: "UTF-8", Data: "<strong>Thanks for joining!</strong>"},
                  Text: %{Charset: "UTF-8", Data: "Thanks for joining!"}
                },
-               Subject: %{Charset: "UTF-8", Data: "Welcome to the app."}
+               Subject: %{Charset: "UTF-8", Data: "Welcome to the app."},
+               Headers: []
              }
            }
   end
diff --git a/test/lib/bamboo/adapters/ses_adapter_test.exs b/test/lib/bamboo/adapters/ses_adapter_test.exs
index 1d84719..ffe8962 100644
--- a/test/lib/bamboo/adapters/ses_adapter_test.exs
+++ b/test/lib/bamboo/adapters/ses_adapter_test.exs
@@ -323,6 +323,7 @@ defmodule Bamboo.SesAdapterTest do
 
     TestHelpers.new_email()
     |> Email.put_header("X-Custom-Header", "header-value; another-value")
+    |> Email.put_attachment(Path.join(__DIR__, "../../../support/invoice.pdf"))
     |> SesAdapter.deliver(%{})
   end
 
@@ -351,6 +352,7 @@ defmodule Bamboo.SesAdapterTest do
     TestHelpers.new_email()
     |> Email.put_header("X-Custom-Header", "header-value")
     |> Email.from({"John [Schmidt]", "from@example.com"})
+    |> Email.put_attachment(Path.join(__DIR__, "../../../support/invoice.pdf"))
     |> SesAdapter.deliver(%{})
   end
 
@@ -377,7 +379,7 @@ defmodule Bamboo.SesAdapterTest do
     expect(HttpMock, :request, expected_request_fn)
 
     TestHelpers.new_email()
-    |> Email.put_header("X-Custom-Header", "header-value")
+    |> Email.put_attachment(Path.join(__DIR__, "../../../support/invoice.pdf"))
     |> Email.put_header("Reply-To", {"John Schmidt", "reply-to@example.com"})
     |> SesAdapter.deliver(%{})
   end