diff --git a/addons/mail/mail_thread.py b/addons/mail/mail_thread.py
index 644b52df2db..76cb942b327 100644
--- a/addons/mail/mail_thread.py
+++ b/addons/mail/mail_thread.py
@@ -449,20 +449,21 @@ class mail_thread(osv.osv):
 
     def _get_user(self, cr, uid, alias, context):
         """
-            return user_id based on alias
-            else return id of admin
+            param alias: browse record of alias.
+            return: int user_id.
         """
 
         user_obj = self.pool.get('res.user')
+        user_id = 1
         if alias.alias_user_id:
             user_id = alias_id.alias_user_id.id
         #if user_id not defined in the alias then search related user using name of Email sender
         else:
-            frm = msg.get('from')
-            user_ids = user_obj.search(cr, uid, [('name','=',frm)], context)
+            from_email = msg.get('from')
+            user_ids = user_obj.search(cr, uid, [('name','=',from_email)], context)
             if user_ids:
                 user_id = user_obj.browse(cr, uid, user_ids[0], context).id
-        return user_id or 1
+        return user_id
 
     def message_catchall(self, cr, uid, message, context=None):
         """
@@ -492,14 +493,14 @@ class mail_thread(osv.osv):
         #if alias found then call message_process method.
         if alias_id:
             user_id = self._get_user(self, cr, uid, alias_id, context)
-            self.message_process(self, cr, user_id, alias_id.alias_model_id.id, message, alias_id.alias_defaults or False , False, False, alias_id.alias_force_thread_id or False, context)
+            self.message_process(self, cr, user_id, alias_id.alias_model_id.id, message, custom_values = alias_id.alias_defaults or {}, thread_id = alias_id.alias_force_thread_id or {}, context)
         #if alis not found give Exception
         else:
-            _logger.warning("This mailbox does not exist so mail gate will reject this mail.")
-            frm = user_obj.browse(cr, uid, uid, context).user_email
+            #_logger.warning("This mailbox does not exist so mail gate will reject this mail.")
+            from_email = user_obj.browse(cr, uid, uid, context).user_email
             sub = "Mail Rejection" + msg.get('subject')
             message = "Respective mailbox does not exist so your mail have been rejected" + msg
-            mail_message.send_mail(cr, uid, {'email_from': frm,'email_to': msg.get('from'),'subject': sub, 'body_text': message}, context)
+            mail_message.send_mail(cr, uid, {'email_from': from_email,'email_to': msg.get('from'),'subject': sub, 'body_text': message}, context)
 
         return True