diff --git a/addons/mail/mail_group.py b/addons/mail/mail_group.py
index 6c40e618342..777251e434a 100644
--- a/addons/mail/mail_group.py
+++ b/addons/mail/mail_group.py
@@ -223,6 +223,9 @@ class mail_group(osv.Model):
         group = self.browse(cr, uid, id, context=context)
         headers = res.setdefault('headers', {})
         headers['Precedence'] = 'list'
+        # avoid out-of-office replies from MS Exchange
+        # http://blogs.technet.com/b/exchange/archive/2006/10/06/3395024.aspx
+        headers['X-Auto-Response-Suppress'] = 'OOF'
         if group.alias_domain:
             headers['List-Id'] = '%s.%s' % (group.alias_name, group.alias_domain)
             headers['List-Post'] = '<mailto:%s@%s>' % (group.alias_name, group.alias_domain)