diff --git a/Lib/email/_parseaddr.py b/Lib/email/_parseaddr.py
index 4d27f87974b20d..ee14ad5c4a8aff 100644
--- a/Lib/email/_parseaddr.py
+++ b/Lib/email/_parseaddr.py
@@ -126,6 +126,8 @@ def _parsedate_tz(data):
             tss = 0
         elif len(tm) == 3:
             [thh, tmm, tss] = tm
+        else:
+            return None
     else:
         return None
     try:
diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
index 044b93862a14eb..c4036fd114f63c 100644
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -3007,6 +3007,7 @@ def test_parsedate_returns_None_for_invalid_strings(self):
         self.assertIsNone(utils.parsedate_tz('0'))
         self.assertIsNone(utils.parsedate('A Complete Waste of Time'))
         self.assertIsNone(utils.parsedate_tz('A Complete Waste of Time'))
+        self.assertIsNone(utils.parsedate_tz('Wed, 3 Apr 2002 12.34.56.78+0800'))
         # Not a part of the spec but, but this has historically worked:
         self.assertIsNone(utils.parsedate(None))
         self.assertIsNone(utils.parsedate_tz(None))
diff --git a/Misc/NEWS.d/next/Library/2021-10-13-17-52-48.bpo-45239.7li1_0.rst b/Misc/NEWS.d/next/Library/2021-10-13-17-52-48.bpo-45239.7li1_0.rst
new file mode 100644
index 00000000000000..9e5ec561c362af
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-10-13-17-52-48.bpo-45239.7li1_0.rst
@@ -0,0 +1,3 @@
+Fixed :func:`email.utils.parsedate_tz` crashing with
+:exc:`UnboundLocalError` on certain invalid input instead of returning
+``None``. Patch by Ben Hoyt.