diff --git a/Doc/library/email.message.rst b/Doc/library/email.message.rst
index aeea942..b91f26d 100644
--- a/Doc/library/email.message.rst
+++ b/Doc/library/email.message.rst
@@ -578,6 +578,15 @@
       will be *failobj*.
 
 
+   .. method:: get_content_disposition()
+
+      Return the lowercased value (without parameters) of the message's
+      :mailheader:`Content-Disposition` header if it has one, or ``None``.  The
+      possible values for this method are *inline*, *attachment* or ``None``
+      if the message follows :rfc:`2183`.
+
+      .. versionadded:: 3.5
+
    .. method:: walk()
 
       The :meth:`walk` method is an all-purpose generator which can be used to
diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
index 4b36315..0360de4 100644
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -348,6 +348,14 @@
   *module* contains no docstrings instead of raising :exc:`ValueError`.
   (Contributed by Glenn Jones in :issue:`15916`.)
 
+email
+-----
+
+* A new method :meth:`~email.message.Message.get_content_disposition` provides
+  easy access to a canonical value for the :mailheader:`Content-Disposition`
+  header (``None`` if there is no such header).  (Contributed by Abhilash Raj
+  in :issue:`21083`.)
+
 glob
 ----
 
diff --git a/Lib/email/message.py b/Lib/email/message.py
index 3d3138f..a892012 100644
--- a/Lib/email/message.py
+++ b/Lib/email/message.py
@@ -927,6 +927,18 @@
         """
         return [part.get_content_charset(failobj) for part in self.walk()]
 
+    def get_content_disposition(self):
+        """Return the message's content-disposition if it exists, or None.
+
+        The return values can be either 'inline', 'attachment' or None
+        according to the rfc2183.
+        """
+        value = self.get('content-disposition')
+        if value is None:
+            return None
+        c_d = _splitparam(value)[0].lower()
+        return c_d
+
     # I.e. def walk(self): ...
     from email.iterators import walk
 
diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index 218ce0c..b627760 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -586,6 +586,17 @@
         eq(msg.values(), ['One Hundred', 'Twenty', 'Three', 'Eleven'])
         self.assertRaises(KeyError, msg.replace_header, 'Fourth', 'Missing')
 
+    def test_get_content_disposition(self):
+        msg = Message()
+        self.assertIsNone(msg.get_content_disposition())
+        msg.add_header('Content-Disposition', 'attachment',
+                       filename='random.avi')
+        self.assertEqual(msg.get_content_disposition(), 'attachment')
+        msg.replace_header('Content-Disposition', 'inline')
+        self.assertEqual(msg.get_content_disposition(), 'inline')
+        msg.replace_header('Content-Disposition', 'InlinE')
+        self.assertEqual(msg.get_content_disposition(), 'inline')
+
     # test_defect_handling:test_invalid_chars_in_base64_payload
     def test_broken_base64_payload(self):
         x = 'AwDp0P7//y6LwKEAcPa/6Q=9'
diff --git a/Misc/ACKS b/Misc/ACKS
index 87a6c4a..71fb0c5 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1134,6 +1134,7 @@
 Ram Rachum
 Jérôme Radix
 Burton Radons
+Abhilash Raj
 Shorya Raj
 Jeff Ramnani
 Brodie Rao