diff --git a/django/core/mail/backends/smtp.py b/django/core/mail/backends/smtp.py
index bb184ab312..3ee283b5f1 100644
--- a/django/core/mail/backends/smtp.py
+++ b/django/core/mail/backends/smtp.py
@@ -18,8 +18,14 @@ class EmailBackend(BaseEmailBackend):
         super(EmailBackend, self).__init__(fail_silently=fail_silently)
         self.host = host or settings.EMAIL_HOST
         self.port = port or settings.EMAIL_PORT
-        self.username = username or settings.EMAIL_HOST_USER
-        self.password = password or settings.EMAIL_HOST_PASSWORD
+        if username is None:
+            self.username = settings.EMAIL_HOST_USER
+        else:
+            self.username = username
+        if password is None:
+            self.password = settings.EMAIL_HOST_PASSWORD
+        else:
+            self.password = password
         if use_tls is None:
             self.use_tls = settings.EMAIL_USE_TLS
         else:
diff --git a/tests/regressiontests/mail/tests.py b/tests/regressiontests/mail/tests.py
index 5d5f52b6cd..08eb7b9f45 100644
--- a/tests/regressiontests/mail/tests.py
+++ b/tests/regressiontests/mail/tests.py
@@ -635,3 +635,24 @@ class SMTPBackendTests(BaseEmailBackendTests, TestCase):
 
     def get_mailbox_content(self):
         return self.server.get_sink()
+
+    @override_settings(EMAIL_HOST_USER="not empty username",
+                        EMAIL_HOST_PASSWORD="not empty password")
+    def test_email_authentication_use_settings(self):
+        backend = smtp.EmailBackend()
+        self.assertEqual(backend.username, 'not empty username')
+        self.assertEqual(backend.password, 'not empty password')
+
+    @override_settings(EMAIL_HOST_USER="not empty username",
+                        EMAIL_HOST_PASSWORD="not empty password")
+    def test_email_authentication_override_settings(self):
+        backend = smtp.EmailBackend(username='username', password='password')
+        self.assertEqual(backend.username, 'username')
+        self.assertEqual(backend.password, 'password')
+
+    @override_settings(EMAIL_HOST_USER="not empty username",
+                        EMAIL_HOST_PASSWORD="not empty password")
+    def test_email_disabled_authentication(self):
+        backend = smtp.EmailBackend(username='', password='')
+        self.assertEqual(backend.username, '')
+        self.assertEqual(backend.password, '')