diff --git a/addons/mass_mailing/mail_thread.py b/addons/mass_mailing/mail_thread.py
index a4ff15a1a3f..524341f88d7 100644
--- a/addons/mass_mailing/mail_thread.py
+++ b/addons/mass_mailing/mail_thread.py
@@ -29,7 +29,7 @@ from openerp.osv import osv
 _logger = logging.getLogger(__name__)
 
 
-class MailThread(osv.Model):
+class MailThread(osv.AbstractModel):
     """ Update MailThread to add the feature of bounced emails and replied emails
     in message_process. """
     _name = 'mail.thread'