Index: roundup/mailer.py
===================================================================
--- roundup/mailer.py	(revision 4212)
+++ roundup/mailer.py	(working copy)
@@ -141,24 +141,23 @@
         elif error_messages_to == "both":
             to.append(dispatcher_email)
 
-        message = self.get_standard_message(to, subject)
+        message = self.get_standard_message(to, subject, multipart=True)
 
         # add the error text
-        part = MIMEText(error)
+        part = MIMEText('\n'.join(error))
         message.attach(part)
 
         # attach the original message to the returned message
+        body = ""
+        for header in bounced_message.headers:
+            body += header
         try:
             bounced_message.rewindbody()
-        except IOError, message:
-            body.write("*** couldn't include message body: %s ***"
-                       % bounced_message)
+        except IOError, errmessage:
+            body += "*** couldn't include message body: %s ***" % errmessage
         else:
-            body.write(bounced_message.fp.read())
-        part = MIMEText(bounced_message.fp.read())
-        part['Content-Disposition'] = 'attachment'
-        for header in bounced_message.headers:
-            part.write(header)
+            body += '\n' + bounced_message.fp.read()
+        part = MIMEText(body)
         message.attach(part)
 
         # send