diff --git a/mellon/adapters.py b/mellon/adapters.py
index 66d62dd..7b84dd3 100644
--- a/mellon/adapters.py
+++ b/mellon/adapters.py
@@ -33,9 +33,11 @@ from django.core.exceptions import PermissionDenied, FieldDoesNotExist
 from django.core.files.storage import default_storage
 from django.contrib import auth
 from django.contrib.auth.models import Group
+from django.contrib import messages
 from django.utils import six
 from django.utils.encoding import force_text
 from django.utils.six.moves.urllib.parse import urlparse
+from django.utils.translation import ugettext as _
 
 from . import utils, app_settings, models
 
@@ -304,6 +306,9 @@ class DefaultAdapter(object):
                                        transient_federation_attribute)
                         return None
             else:
+                if self.request:
+                    messages.warning(self.request, _('A transient NameID was received but TRANSIENT_FEDERATION_ATTRIBUTE is not set.'))
+                logger.warning('transient NameID was received but TRANSIENT_FEDERATION_ATTRIBUTE is not set')
                 return None
         else:
             name_id = saml_attributes['name_id_content']
diff --git a/tests/test_default_adapter.py b/tests/test_default_adapter.py
index fa79360..43a755d 100644
--- a/tests/test_default_adapter.py
+++ b/tests/test_default_adapter.py
@@ -21,6 +21,7 @@ import lasso
 import time
 from multiprocessing.pool import ThreadPool
 
+import mock
 import pytest
 
 from django.contrib import auth
@@ -29,6 +30,7 @@ from django.db import connection
 from mellon.adapters import DefaultAdapter
 from mellon.backends import SAMLBackend
 
+
 pytestmark = pytest.mark.django_db
 
 User = auth.get_user_model()
@@ -212,11 +214,18 @@ def test_provision_long_attribute(settings, django_user_model, idp, saml_attribu
     assert 'set field email' in caplog.text
 
 
-def test_lookup_user_transient_with_email(private_settings, idp, saml_attributes):
-    private_settings.MELLON_TRANSIENT_FEDERATION_ATTRIBUTE = 'email'
-    adapter = DefaultAdapter()
+def test_lookup_user_transient_with_email(rf, private_settings, idp, saml_attributes):
+    request = rf.get('/')
+    request._messages = mock.Mock()
+    adapter = DefaultAdapter(request=request)
     saml_attributes['name_id_format'] = lasso.SAML2_NAME_IDENTIFIER_FORMAT_TRANSIENT
     assert User.objects.count() == 0
+
+    user = adapter.lookup_user(idp, saml_attributes)
+    assert User.objects.count() == 0
+    request._messages.add.assert_called_once_with(30, 'A transient NameID was received but TRANSIENT_FEDERATION_ATTRIBUTE is not set.', '')
+
+    private_settings.MELLON_TRANSIENT_FEDERATION_ATTRIBUTE = 'email'
     user = adapter.lookup_user(idp, saml_attributes)
     assert user is not None
     assert user.saml_identifiers.count() == 1