diff --git a/addons/mail/wizard/mail_compose_message.py b/addons/mail/wizard/mail_compose_message.py
index cb068d566c1..d51118c34e6 100644
--- a/addons/mail/wizard/mail_compose_message.py
+++ b/addons/mail/wizard/mail_compose_message.py
@@ -244,6 +244,8 @@ class mail_compose_message(osv.TransientModel):
     def get_mail_values(self, cr, uid, wizard, res_ids, context=None):
         """Generate the values that will be used by send_mail to create mail_messages
         or mail_mails. """
+        import pudb
+        pudb.set_trace()
         results = dict.fromkeys(res_ids, False)
         rendered_values, default_recipients = {}, {}
         mass_mail_mode = wizard.composition_mode == 'mass_mail'
diff --git a/addons/mass_mailing/models/mass_mailing.py b/addons/mass_mailing/models/mass_mailing.py
index 18c5ad53928..bfeb3aeeafe 100644
--- a/addons/mass_mailing/models/mass_mailing.py
+++ b/addons/mass_mailing/models/mass_mailing.py
@@ -571,6 +571,7 @@ class MassMailing(osv.Model):
                 'composition_mode': 'mass_mail',
                 'mass_mailing_id': mailing.id,
                 'mailing_list_ids': [(4, l.id) for l in mailing.contact_list_ids],
+                'same_thread': mailing.reply_to_mode == 'thread',
             }
             if mailing.reply_to_mode == 'email':
                 composer_values['reply_to'] = mailing.reply_to