diff --git a/lib/mail.ex b/lib/mail.ex
index 8533922..ed3e763 100644
--- a/lib/mail.ex
+++ b/lib/mail.ex
@@ -191,18 +191,30 @@ defmodule Mail do
     do: Mail.Message.put_attachment(message, {filename, data}, opts)
 
   @doc """
-  Determines the message has any attachment parts
+  Determines the message has any non-inline attachment parts
 
   Returns a `Boolean`
   """
   def has_attachments?(%Mail.Message{} = message) do
-    walk_parts([message], {:cont, false}, fn message, _acc ->
-      case Mail.Message.is_attachment?(message) do
-        true -> {:halt, true}
-        false -> {:cont, false}
-      end
-    end)
-    |> elem(1)
+    has_message?(message, &Mail.Message.is_attachment?/1)
+  end
+
+  @doc """
+  Determines the message has any inline attachment parts
+
+  Returns a `Boolean`
+  """
+  def has_inline_attachments?(%Mail.Message{} = message) do
+    has_message?(message, &Mail.Message.is_inline_attachment?/1)
+  end
+
+  @doc """
+  Determines the message has any inline attachment parts
+
+  Returns a `Boolean`
+  """
+  def has_any_attachments?(%Mail.Message{} = message) do
+    has_message?(message, &Mail.Message.is_any_attachment?/1)
   end
 
   @doc """
@@ -211,8 +223,12 @@ defmodule Mail do
   Returns a `Boolean`
   """
   def has_text_parts?(%Mail.Message{} = message) do
+    has_message?(message, &Mail.Message.is_text_part?/1)
+  end
+
+  defp has_message?(%Mail.Message{} = message, condition) do
     walk_parts([message], {:cont, false}, fn message, _acc ->
-      case Mail.Message.is_text_part?(message) do
+      case condition.(message) do
         true -> {:halt, true}
         false -> {:cont, false}
       end
diff --git a/lib/mail/message.ex b/lib/mail/message.ex
index 59ec8a8..e3e571e 100644
--- a/lib/mail/message.ex
+++ b/lib/mail/message.ex
@@ -14,9 +14,16 @@ defmodule Mail.Message do
       iex> Mail.Message.put_part(%Mail.Message{}, %Mail.Message{})
       %Mail.Message{parts: [%Mail.Message{}]}
   """
-  def put_part(message, %Mail.Message{} = part) do
-    put_in(message.parts, message.parts ++ [part])
-  end
+  def put_part(message, %Mail.Message{} = part),
+    do: put_in(message.parts, message.parts ++ [part])
+
+  @doc """
+  Add an arbitrary amount of parts
+
+      Mail.Message.put_parts(%Mail.Message{}, [%Mail.Message{}, %Mail.Message{}])
+  """
+  def put_parts(message, parts) when is_list(parts),
+    do: put_in(message.parts, message.parts ++ parts)
 
   @doc """
   Delete a matching part
@@ -27,6 +34,12 @@ defmodule Mail.Message do
   def delete_part(message, part),
     do: put_in(message.parts, List.delete(message.parts, part))
 
+  @doc """
+  Will remove all parts from message.
+  """
+  def delete_all_parts(message),
+    do: put_in(message.parts, [])
+
   @doc """
   Will match on a full or partial content type
 
@@ -373,7 +386,7 @@ defmodule Mail.Message do
   end
 
   @doc """
-  Is the part an attachment or not
+  Is the part a non-inline attachment or not
 
   Returns `Boolean`
   """
@@ -381,7 +394,7 @@ defmodule Mail.Message do
     do: Enum.member?(List.wrap(get_header(message, :content_disposition)), "attachment")
 
   @doc """
-  Determines the message has any attachment parts
+  Determines the message has any non-inline attachment parts
 
   Returns a `Boolean`
   """
@@ -391,6 +404,33 @@ defmodule Mail.Message do
   def has_attachment?(message),
     do: has_attachment?(message.parts)
 
+  @doc """
+  Is the part an inline attachment or not
+
+  Returns `Boolean`
+  """
+  def is_inline_attachment?(message),
+    do: Enum.member?(List.wrap(get_header(message, :content_disposition)), "inline")
+
+  @doc """
+  Determines the message has any inline attachment parts
+
+  Returns a `Boolean`
+  """
+  def has_inline_attachment?(parts) when is_list(parts),
+    do: has_part?(parts, &is_inline_attachment?/1)
+
+  def has_inline_attachment?(message),
+    do: has_inline_attachment?(message.parts)
+
+  @doc """
+  Is the part any kind of attachment or not
+
+  Returns `Boolean`
+  """
+  def is_any_attachment?(message),
+    do: is_inline_attachment?(message) || is_attachment?(message)
+
   @doc """
   Is the message text based or not
 
diff --git a/lib/mail/renderers/rfc_2822.ex b/lib/mail/renderers/rfc_2822.ex
index d41fe28..66d244d 100644
--- a/lib/mail/renderers/rfc_2822.ex
+++ b/lib/mail/renderers/rfc_2822.ex
@@ -251,30 +251,83 @@ defmodule Mail.Renderers.RFC2822 do
     |> String.pad_leading(2, "0")
   end
 
-  defp reorganize(%Mail.Message{multipart: true} = message) do
+  defp split_attachment_parts(message) do
+    Enum.reduce(message.parts, [[], [], []], fn part, [texts, mixed, inlines] ->
+      cond do
+        match_content_type?(part, ~r/text\/(plain|html)/) ->
+          [[part | texts], mixed, inlines]
+        Mail.Message.is_inline_attachment?(part) ->
+          [texts, mixed, [part | inlines]]
+        true -> # a mixed part - most likely an attachment
+          [texts, [part | mixed], inlines]
+      end
+    end)
+    |> Enum.map(&Enum.reverse/1) # retain ordering
+  end
+
+  @doc """
+  Will organize message parts to conform to expectations on MIME-part order,
+  specifically in the following format:
+
+      start multipart/mixed
+        start multipart/related
+          start multipart/alternative
+            <text and html parts>
+          end multipart/alternative
+          <inline parts>
+        end multipart/related
+        <attachment parts>
+      end multipart/mixed
+
+  Such that:
+
+  - text and html parts will be grouped in a `multipart/alternative`;
+  - inline attachments will be postpended and grouped with text and html parts
+    in a `multipart/related` (RFC 2387); and
+  - regular attachments will be postpended and grouped with all content in a
+    `multipart/mixed`
+  """
+  def reorganize(%Mail.Message{multipart: true} = message) do
     content_type = Mail.Message.get_content_type(message)
 
-    if Mail.Message.has_attachment?(message) do
-      text_parts =
-        Enum.filter(message.parts, &match_content_type?(&1, ~r/text\/(plain|html)/))
-        |> Enum.sort(&(&1 > &2))
+    [text_parts, mixed, inlines] = split_attachment_parts(message)
+    has_inline = Enum.any?(inlines)
+    has_mixed_parts = Enum.any?(mixed)
+    has_text_parts = Enum.any?(text_parts)
 
+    if has_inline || has_mixed_parts do
+      # If any attaching, change content type to mixed
       content_type = List.replace_at(content_type, 0, "multipart/mixed")
       message = Mail.Message.put_content_type(message, content_type)
 
-      if Enum.any?(text_parts) do
-        message = Enum.reduce(text_parts, message, &Mail.Message.delete_part(&2, &1))
-
-        mixed_part =
+      if has_text_parts do
+        # If any text with attachments, wrap in new part
+        body_part =
           Mail.build_multipart()
           |> Mail.Message.put_content_type("multipart/alternative")
+          |> Mail.Message.put_parts(text_parts)
+
+        # If any inline attachments, wrap together with text
+        # in a "multipart/related" part
+        body_part = if has_inline do
+          Mail.build_multipart()
+          |> Mail.Message.put_content_type("multipart/related")
+          |> Mail.Message.put_part(body_part)
+          |> Mail.Message.put_parts(inlines)
+        else
+          body_part
+        end
 
-        mixed_part = Enum.reduce(text_parts, mixed_part, &Mail.Message.put_part(&2, &1))
-        put_in(message.parts, List.insert_at(message.parts, 0, mixed_part))
+        message
+        |> Mail.Message.delete_all_parts()
+        |> Mail.Message.put_part(body_part)
+        |> Mail.Message.put_parts(mixed)
       else
+        # If not text sections, leave all parts as is
         message
       end
     else
+      # If only text, change content type to alternative
       content_type = List.replace_at(content_type, 0, "multipart/alternative")
       Mail.Message.put_content_type(message, content_type)
     end
diff --git a/test/mail/renderers/rfc_2822_test.exs b/test/mail/renderers/rfc_2822_test.exs
index 3c928c0..ef5a846 100644
--- a/test/mail/renderers/rfc_2822_test.exs
+++ b/test/mail/renderers/rfc_2822_test.exs
@@ -339,4 +339,143 @@ defmodule Mail.Renderers.RFC2822Test do
       |> Mail.Renderers.RFC2822.render()
     end
   end
+
+  test "will have correct part order for regular message" do
+    message =
+      Mail.build_multipart()
+      |> Mail.put_to("user1@example.com")
+      |> Mail.put_from({"User2", "user2@example.com"})
+      |> Mail.put_subject("Test email")
+      |> Mail.put_text("Some text")
+      |> Mail.put_html("<h1>Some HTML</h1>")
+      |> Mail.Renderers.RFC2822.reorganize()
+
+    assert %Mail.Message{
+             headers: %{"content-type" => ["multipart/alternative"]},
+             parts: [
+               %Mail.Message{
+                 headers: %{"content-type" => ["text/plain", {"charset", "UTF-8"}]},
+                 body: "Some text",
+                 parts: [],
+                 multipart: false
+               },
+               %Mail.Message{
+                 headers: %{"content-type" => ["text/html", {"charset", "UTF-8"}]},
+                 body: "<h1>Some HTML</h1>",
+                 parts: [],
+                 multipart: false
+               }
+             ]
+           } = message
+  end
+
+  test "will have correct part order with only a regular attachment" do
+    message =
+      Mail.build_multipart()
+      |> Mail.put_to("user1@example.com")
+      |> Mail.put_from({"User2", "user2@example.com"})
+      |> Mail.put_subject("Test email")
+      |> Mail.put_attachment({"tiny_jpeg.jpg", @tiny_jpeg_binary})
+      |> Mail.put_text("Some text")
+      |> Mail.put_html("<h1>Some HTML</h1>")
+      |> Mail.Renderers.RFC2822.reorganize()
+
+    assert %Mail.Message{
+             headers: %{"content-type" => ["multipart/mixed"]},
+             parts: [
+               %Mail.Message{
+                 headers: %{"content-type" => ["multipart/alternative"]},
+                 parts: [
+                   %Mail.Message{
+                     headers: %{"content-type" => ["text/plain", {"charset", "UTF-8"}]},
+                     body: "Some text",
+                     parts: [],
+                     multipart: false
+                   },
+                   %Mail.Message{
+                     headers: %{"content-type" => ["text/html", {"charset", "UTF-8"}]},
+                     body: "<h1>Some HTML</h1>",
+                     parts: [],
+                     multipart: false
+                   }
+                 ]
+               },
+               %Mail.Message{
+                 headers: %{
+                   "content-transfer-encoding" => :base64,
+                   "content-type" => ["image/jpeg"]
+                 },
+                 parts: [],
+                 multipart: false
+               }
+             ]
+           } = message
+  end
+
+  test "will have correct part order with inline attachment" do
+    message =
+      Mail.build_multipart()
+      |> Mail.put_to("user1@example.com")
+      |> Mail.put_from({"User2", "user2@example.com"})
+      |> Mail.put_subject("Test email")
+      |> Mail.put_attachment({"tiny_jpeg.jpg", @tiny_jpeg_binary})
+      |> Mail.put_attachment({"inline_jpeg.jpg", @tiny_jpeg_binary},
+        headers: %{
+          content_id: "c_id",
+          content_type: "image/jpeg",
+          x_attachment_id: "a_id",
+          content_disposition: ["inline", filename: "filename"]
+        }
+      )
+      |> Mail.put_text("Some text")
+      |> Mail.put_html("<h1>Some HTML</h1>")
+      |> Mail.Renderers.RFC2822.reorganize()
+
+    assert %Mail.Message{
+             headers: %{"content-type" => ["multipart/mixed"]},
+             parts: [
+               %Mail.Message{
+                 headers: %{"content-type" => ["multipart/related"]},
+                 parts: [
+                   %Mail.Message{
+                     headers: %{"content-type" => ["multipart/alternative"]},
+                     parts: [
+                       %Mail.Message{
+                         headers: %{"content-type" => ["text/plain", {"charset", "UTF-8"}]},
+                         body: "Some text",
+                         parts: [],
+                         multipart: false
+                       },
+                       %Mail.Message{
+                         headers: %{"content-type" => ["text/html", {"charset", "UTF-8"}]},
+                         body: "<h1>Some HTML</h1>",
+                         parts: [],
+                         multipart: false
+                       }
+                     ]
+                   },
+                   %Mail.Message{
+                     headers: %{
+                       "content-transfer-encoding" => :base64,
+                       "content-type" => "image/jpeg",
+                       "content-id" => "c_id",
+                       "content-disposition" => ["inline", {:filename, "filename"}],
+                       "x-attachment-id" => "a_id",
+                     },
+                     parts: [],
+                     multipart: false
+                   }
+                 ]
+               },
+               %Mail.Message{
+                 headers: %{
+                   "content-transfer-encoding" => :base64,
+                   "content-type" => ["image/jpeg"]
+                 },
+                 parts: [],
+                 multipart: false
+               }
+             ]
+           } = message
+  end
 end