diff --git a/addons/mass_mailing/tests/test_mailing_controllers.py b/addons/mass_mailing/tests/test_mailing_controllers.py
index a7777616ab8..49ad26ef02b 100644
--- a/addons/mass_mailing/tests/test_mailing_controllers.py
+++ b/addons/mass_mailing/tests/test_mailing_controllers.py
@@ -35,7 +35,8 @@ class TestMailingControllers(MassMailCommon, HttpCase):
         # freeze time base value
         cls._reference_now = datetime.datetime(2022, 6, 14, 10, 0, 0)
 
-    def _request_handler(self, s: Session, r: PreparedRequest, /, **kw):
+    @classmethod
+    def _request_handler(cls, s: Session, r: PreparedRequest, /, **kw):
         if r.url.startswith('https://www.example.com/foo/bar'):
             r = Response()
             r.status_code = 200
diff --git a/odoo/tests/common.py b/odoo/tests/common.py
index ab381bad1c3..d70fef9337c 100644
--- a/odoo/tests/common.py
+++ b/odoo/tests/common.py
@@ -244,6 +244,8 @@ def _normalize_arch_for_assert(arch_string, parser_method="xml"):
     arch_string = etree.fromstring(arch_string, parser=parser)
     return etree.tostring(arch_string, pretty_print=True, encoding='unicode')
 
+class BlockedRequest(requests.exceptions.ConnectionError):
+    pass
 _super_send = requests.Session.send
 class BaseCase(case.TestCase, metaclass=MetaCase):
     """ Subclass of TestCase for Odoo-specific code. This class is abstract and
@@ -258,21 +260,9 @@ class BaseCase(case.TestCase, metaclass=MetaCase):
         super().__init__(methodName)
         self.addTypeEqualityFunc(etree._Element, self.assertTreesEqual)
         self.addTypeEqualityFunc(html.HtmlElement, self.assertTreesEqual)
-        self.request_mock = None
 
-    def setUp(self):
-        super().setUp()
-        if 'external' not in self.test_tags:
-            # if the method is passed directly `patch` discards the session
-            # object which we need
-            # pylint: disable=unnecessary-lambda
-            self.patch(
-                requests.sessions.Session,
-                'send',
-                lambda s, r, **kwargs: self._request_handler(s, r, **kwargs),
-            )
-
-    def _request_handler(self, s: Session, r: PreparedRequest, /, **kw):
+    @classmethod
+    def _request_handler(cls, s: Session, r: PreparedRequest, /, **kw):
         # allow localhost requests
         # TODO: also check port?
         url = werkzeug.urls.url_parse(r.url)
@@ -283,8 +273,7 @@ class BaseCase(case.TestCase, metaclass=MetaCase):
 
         _logger.getChild('requests').info(
             "Blocking un-mocked external HTTP request %s %s", r.method, r.url)
-        raise requests.exceptions.ConnectionError(
-            f"External requests verboten (was {r.method} {r.url})")
+        raise BlockedRequest(f"External requests verboten (was {r.method} {r.url})")
 
     def run(self, result):
         testMethod = getattr(self, self._testMethodName)
@@ -318,6 +307,17 @@ class BaseCase(case.TestCase, metaclass=MetaCase):
                 patcher.stop()
         cls.addClassCleanup(check_remaining_patchers)
         super().setUpClass()
+        if 'standard' in cls.test_tags:
+            # if the method is passed directly `patch` discards the session
+            # object which we need
+            # pylint: disable=unnecessary-lambda
+            patcher = patch.object(
+                requests.sessions.Session,
+                'send',
+                lambda s, r, **kwargs: cls._request_handler(s, r, **kwargs),
+            )
+            patcher.start()
+            cls.addClassCleanup(patcher.stop)
 
     def cursor(self):
         return self.registry.cursor()
@@ -792,8 +792,6 @@ class TransactionCase(BaseCase):
         self.cr.execute('SAVEPOINT test_%d' % self._savepoint_id)
         self.addCleanup(self.cr.execute, 'ROLLBACK TO SAVEPOINT test_%d' % self._savepoint_id)
 
-        self.patch(self.registry['res.partner'], '_get_gravatar_image', lambda *a: False)
-
 
 class SingleTransactionCase(BaseCase):
     """ TestCase in which all test methods are run in the same transaction,