'Regression test for #15042'

def test_recipient_without_domain(self):

    self.assertTrue(send_mail(u'Subject', u'Content', u'tester', [u'django']))
    message = self.get_the_message()
    self.assertEqual(message.get(u'subject'), u'Subject')
    self.assertEqual(message.get(u'from'), u'tester')
    self.assertEqual(message.get(u'to'), u'django')
