Closes #14158: We now track test_support.TESTFN cleanup, and test_mailbox uses shutil.rmtree for simpler code.
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index a68686e..d0538be 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -6,6 +6,7 @@
 import email
 import email.message
 import re
+import shutil
 import StringIO
 from test import test_support
 import unittest
@@ -38,12 +39,7 @@
     def _delete_recursively(self, target):
         # Delete a file or delete a directory recursively
         if os.path.isdir(target):
-            for path, dirs, files in os.walk(target, topdown=False):
-                for name in files:
-                    os.remove(os.path.join(path, name))
-                for name in dirs:
-                    os.rmdir(os.path.join(path, name))
-            os.rmdir(target)
+            shutil.rmtree(target)
         elif os.path.exists(target):
             os.remove(target)