1 files changed, 13 insertions, 8 deletions

diff --git a/src/mailman_pgp/pgp/mime.py b/src/mailman_pgp/pgp/mime.py
index 751b9e5..92ee72b 100644
--- a/src/mailman_pgp/pgp/mime.py
+++ b/src/mailman_pgp/pgp/mime.py
@@ -21,9 +21,9 @@ from email import message_from_string
 from email.encoders import encode_7or8bit
 from email.iterators import walk
 from email.mime.application import MIMEApplication
-from email.mime.multipart import MIMEMultipart
 from email.utils import collapse_rfc2231_value
 
+from mailman.email.message import Message, MultipartDigestMessage
 from pgpy import PGPKey, PGPMessage, PGPSignature
 from pgpy.constants import HashAlgorithm, SymmetricKeyAlgorithm
 from public import public
@@ -43,6 +43,11 @@ class MIMEWrapper:
     _encrypted_type = 'application/' + _encryption_subtype
     _keys_type = 'application/' + _keys_subtype
 
+    _signature_preamble = \
+        'This is an OpenPGP/MIME signed message (RFC 4880 and 3156)'
+    _encryption_preamble = \
+        'This is an OpenPGP/MIME encrypted message (RFC 4880 and 3156)'
+
     def __init__(self, msg):
         """
         Wrap the given message.
@@ -170,9 +175,9 @@ class MIMEWrapper:
         signature = key.sign(pmsg, hash=hash)
 
         micalg = self._micalg(signature.hash_algorithm)
-        out = MIMEMultipart('signed', micalg=micalg,
-                            protocol=MIMEWrapper._signed_type)
-        out.preamble = 'This is an OpenPGP/MIME signed message (RFC 4880 and 3156)'
+        out = MultipartDigestMessage('signed', micalg=micalg,
+                                     protocol=MIMEWrapper._signed_type)
+        out.preamble = MIMEWrapper._signature_preamble
 
         second_part = MIMEApplication(_data=str(signature),
                                       _subtype=MIMEWrapper._signature_subtype,
@@ -200,7 +205,7 @@ class MIMEWrapper:
         msg_text = self.msg.get_payload(1).get_payload()
         pmsg = PGPMessage.from_blob(msg_text)
         decrypted = key.decrypt(pmsg)
-        out = message_from_string(decrypted.message)
+        out = message_from_string(decrypted.message, _class=Message)
         copy_headers(self.msg, out)
         return out
 
@@ -225,9 +230,9 @@ class MIMEWrapper:
                                    session_key=session_key)
             del session_key
 
-        out = MIMEMultipart('encrypted',
-                            protocol=MIMEWrapper._encrypted_type)
-        out.preamble = 'This is an OpenPGP/MIME encrypted message (RFC 4880 and 3156)'
+        out = MultipartDigestMessage('encrypted',
+                                     protocol=MIMEWrapper._encrypted_type)
+        out.preamble = MIMEWrapper._encryption_preamble
 
         first_part = MIMEApplication(_data='Version: 1',
                                      _subtype=MIMEWrapper._encryption_subtype,