diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index 56a80631c97f18..0e3f6d1dfec4eb 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -3319,6 +3319,23 @@ def test_parsing_errors(self):
         # Test email.utils.supports_strict_parsing attribute
         self.assertEqual(email.utils.supports_strict_parsing, True)
 
+    def test_parseaddr_unicode(self):
+        # CVE-2023-27043 Unicode regression guard. The 2.7 refactor had to
+        # accept both str and unicode at the parseaddr() boundary; in Python 3
+        # str is already Unicode, so this test just pins that strict-mode
+        # parsing still accepts valid non-ASCII input and agrees with the
+        # non-strict path.
+        for addr in (
+            'user@example.com',
+            'Test User <user@example.com>',
+            '"Test User" <user@example.com>',
+            '"Sürname, Firstname" <to@example.com>',
+        ):
+            with self.subTest(addr=addr):
+                strict = utils.parseaddr(addr, strict=True)
+                self.assertNotEqual(strict, ('', ''))
+                self.assertEqual(strict, utils.parseaddr(addr, strict=False))
+
     def test_getaddresses_nasty(self):
         for addresses, expected in (
             (['"Sürname, Firstname" <to@example.com>'],