diff --git a/product/ERP5Type/tests/utils.py b/product/ERP5Type/tests/utils.py
index a96c32f0d5ae2eccceec498fdfd7561f033cd024..6b3804838379fc8a2e47d4982b7a10727633df5a 100644
--- a/product/ERP5Type/tests/utils.py
+++ b/product/ERP5Type/tests/utils.py
@@ -107,6 +107,8 @@ class DummyMailHostMixin(object):
   @staticmethod
   def _decodeMessage(messageText):
     """ Decode message"""
+    if six.PY3 and isinstance(messageText, bytes):
+      messageText = messageText.decode()
     message_text = messageText
     for part in message_from_string(messageText).walk():
       if part.get_content_type() in ['text/plain', 'text/html' ] \