diff --git a/Lib/test/test_smtplib.py b/Lib/test/test_smtplib.py
index 81806c9..2fcf382 100644
--- a/Lib/test/test_smtplib.py
+++ b/Lib/test/test_smtplib.py
@@ -479,6 +479,14 @@ class SMTPSimTests(unittest.TestCase):
         expected_auth_ok = (235, b'plain auth ok')
         self.assertEqual(smtp.login(sim_auth[0], sim_auth[1]), expected_auth_ok)
 
+    def testAUTH_PLAIN_unicode_user(self):
+        self.serv.add_feature("AUTH PLAIN")
+        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
+
+        expected_auth_ok = (235, b'plain auth ok')
+        self.assertEqual(smtp.login(unicode(sim_auth[0]), sim_auth[1]), expected_auth_ok)
+
+
     # SimSMTPChannel doesn't fully support LOGIN or CRAM-MD5 auth because they
     # require a synchronous read to obtain the credentials...so instead smtpd
     # sees the credential sent by smtplib's login method as an unknown command,
@@ -504,6 +512,25 @@ class SMTPSimTests(unittest.TestCase):
             if sim_auth_credentials['cram-md5'] not in str(err):
                 raise "expected encoded credentials not found in error message"
 
+    def testAUTH_CRAM_MD5_unicode_user(self):
+        self.serv.add_feature("AUTH CRAM-MD5")
+        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
+        try: smtp.login(unicode(sim_auth[0]), sim_auth[1])
+        except smtplib.SMTPAuthenticationError as err:
+            if sim_auth_credentials['cram-md5'] not in str(err):
+                raise "expected encoded credentials not found in error message"
+
+    def test_unicode_login_fails_gracefully_plain(self):
+        self.serv.add_feature("AUTH PLAIN")
+        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
+        self.assertRaises(UnicodeEncodeError, smtp.login, u'bj\u00F6rn@domain.com', 'somepassword')
+
+    def test_unicode_login_fails_gracefully_auth_cram_md5(self):
+        self.serv.add_feature("AUTH CRAM-MD5")
+        smtp = smtplib.SMTP(HOST, self.port, local_hostname='localhost', timeout=15)
+        self.assertRaises(UnicodeEncodeError, smtp.login, u'bj\u00F6rn@domain.com', 'somepassword')
+
+
     #TODO: add tests for correct AUTH method fallback now that the
     #test infrastructure can support it.