Update reply to to match API format

Author: Rich Leland

sparkpost/django/message.py

@@ -33,7 +33,7 @@ def __init__(self, message):
             formatted['bcc'] = message.bcc
 
         if hasattr(message, 'reply_to') and message.reply_to:
-            formatted['reply_to'] = message.reply_to
+            formatted['reply_to'] = ','.join(message.reply_to)
 
         if isinstance(message, EmailMultiAlternatives):
             for alternative in message.alternatives:

test/django/test_message.py

@@ -77,8 +77,8 @@ def test_attachment():
 if at_least_version('1.8'):
     def test_reply_to():
         expected = dict(
-            reply_to=['replyto@example.com']
+            reply_to='replyone@example.com,[email protected]'
         )
         expected.update(base_expected)
 
-        assert message(reply_to=['replyto@example.com']) == expected
+        assert message(reply_to=['[email protected]', 'replytwo@example.com']) == expected