diff --git a/certbot-postfix/certbot_postfix/installer.py b/certbot-postfix/certbot_postfix/installer.py
index 11d948cb6..e7707359f 100644
--- a/certbot-postfix/certbot_postfix/installer.py
+++ b/certbot-postfix/certbot_postfix/installer.py
@@ -5,6 +5,7 @@ import os
 from functools import partial
 
 import zope.interface
+import six
 
 from certbot import errors
 from certbot import interfaces
@@ -188,7 +189,7 @@ class Installer(plugins_common.Installer):
     def _set_vars(self, var_dict):
         """Sets all parameters in var_dict to config file.
         """
-        for param, acceptable in var_dict.iteritems():
+        for param, acceptable in six.iteritems(var_dict):
             if isinstance(acceptable, tuple):
                 if self.postconf.get(param) not in acceptable:
                     self.postconf.set(param, acceptable[0],
@@ -223,10 +224,10 @@ class Installer(plugins_common.Installer):
                           check_override=util.report_master_overrides)
 
     def _enable_policy_list(self, domain, options):
+        # pylint: disable=unused-argument
         if self._starttls_policy_enabled:
             return
         self._starttls_policy_enabled = True
-        # pylint: disable=unused-argument
         try:
             from starttls_policy import policy
         except ImportError:
diff --git a/certbot-postfix/certbot_postfix/postconf.py b/certbot-postfix/certbot_postfix/postconf.py
index 6c34adbcb..5f2f150bd 100644
--- a/certbot-postfix/certbot_postfix/postconf.py
+++ b/certbot-postfix/certbot_postfix/postconf.py
@@ -101,7 +101,7 @@ class ConfigMain(util.PostfixUtilBase):
             self._get_output(args)
         except:
             raise errors.PluginError("Unable to save to Postfix config!")
-        for name, value in self._updated.iteritems():
+        for name, value in six.iteritems(self._updated):
             self._db[name] = value
         self._updated = {}
 
diff --git a/certbot-postfix/certbot_postfix/tests/postconf_test.py b/certbot-postfix/certbot_postfix/tests/postconf_test.py
index b28a20b05..e60352e9b 100644
--- a/certbot-postfix/certbot_postfix/tests/postconf_test.py
+++ b/certbot-postfix/certbot_postfix/tests/postconf_test.py
@@ -2,63 +2,48 @@
 
 import os
 import pkg_resources
-import random
 import shutil
-import string
-import tempfile
 import unittest
 
+from certbot.tests import util as test_util
+
 # TODO (sydneyli): Mock out calls to postconf
-# TODO (sydneyli): inherit certbot.tests.util.TempDirTestCase
 
-def _rand_str(n):
-    """Returns a random string with length n, for use as a temporary directory."""
-    return ''.join([random.choice(string.lowercase) for _ in xrange(n)])
-
-class PostConfTest(unittest.TestCase):
+class PostConfTest(test_util.TempDirTestCase):
     """Tests for certbot_postfix.util.PostfixUtilBase."""
     def setUp(self):
         from certbot_postfix.postconf import ConfigMain
-        self.tmpdir = tempfile.mkdtemp(suffix=_rand_str(10))
+        super(PostConfTest, self).setUp()
         _config_file = pkg_resources.resource_filename("certbot_postfix.tests",
                            os.path.join("testdata", "small.cf"))
-        self.config_path = os.path.join(self.tmpdir, 'main.cf')
+        self.config_path = os.path.join(self.tempdir, 'main.cf')
         shutil.copyfile(_config_file, self.config_path)
-        self.config = ConfigMain('postconf', self.tmpdir)
+        self.config = ConfigMain('postconf', self.tempdir)
 
     def test_read_defalut(self):
         self.assertEqual(self.config.get_default('smtpd_sasl_auth_enable'), 'no')
 
     def test_read_write(self):
-        try:
-            self.config.set('inet_interfaces', '127.0.0.1')
-            self.config.flush()
-            with open(self.config_path) as f:
-                self.assertTrue('inet_interfaces = 127.0.0.1\n' in f.readlines())
-        finally:
-            shutil.rmtree(self.tmpdir)
+        self.config.set('inet_interfaces', '127.0.0.1')
+        self.config.flush()
+        with open(self.config_path) as f:
+            self.assertTrue('inet_interfaces = 127.0.0.1\n' in f.readlines())
 
     def test_write_revert(self):
-        try:
-            self.config.set('postscreen_forbidden_commands', 'dummy_value')
-            # revert config set
-            self.config.set('postscreen_forbidden_commands', '$smtpd_forbidden_commands')
-            self.config.flush()
-            with open(self.config_path) as f:
-                self.assertTrue(not any('postscreen_forbidden_commands' in line \
-                                    for line in f.readlines()))
-        finally:
-            shutil.rmtree(self.tmpdir)
+        self.config.set('postscreen_forbidden_commands', 'dummy_value')
+        # revert config set
+        self.config.set('postscreen_forbidden_commands', '$smtpd_forbidden_commands')
+        self.config.flush()
+        with open(self.config_path) as f:
+            self.assertTrue(not any('postscreen_forbidden_commands' in line \
+                                for line in f.readlines()))
 
     def test_write_default(self):
-        try:
-            self.config.set('postscreen_forbidden_commands', '$smtpd_forbidden_commands')
-            self.config.flush()
-            with open(self.config_path) as f:
-                self.assertTrue(not any('postscreen_forbidden_commands' in line \
-                                    for line in f.readlines()))
-        finally:
-            shutil.rmtree(self.tmpdir)
+        self.config.set('postscreen_forbidden_commands', '$smtpd_forbidden_commands')
+        self.config.flush()
+        with open(self.config_path) as f:
+            self.assertTrue(not any('postscreen_forbidden_commands' in line \
+                                for line in f.readlines()))
 
 if __name__ == '__main__':  # pragma: no cover
     unittest.main()