diff --git a/addons/mass_mailing/tests/test_mailing_internals.py b/addons/mass_mailing/tests/test_mailing_internals.py
index bc5408c288b..967420bc8a5 100644
--- a/addons/mass_mailing/tests/test_mailing_internals.py
+++ b/addons/mass_mailing/tests/test_mailing_internals.py
@@ -213,6 +213,79 @@ class TestMassMailFeatures(MassMailCommon, CronMixinCase):
                     capt.records.ensure_one()
                     self.assertLessEqual(capt.records.call_at, truth)
 
+    @users('user_marketing')
+    @mute_logger('odoo.addons.mail.models.mail_mail')
+    def test_mailing_deletion(self):
+        """ Test deletion in various use case, depending on reply-to """
+        # 1- Keep archives and reply-to set to 'answer = new thread'
+        mailing = self.env['mailing.mailing'].create({
+            'name': 'TestSource',
+            'subject': 'TestDeletion',
+            'body_html': "<div>Hello {object.name}</div>",
+            'mailing_model_id': self.env['ir.model']._get('mailing.list').id,
+            'contact_list_ids': [(6, 0, self.mailing_list_1.ids)],
+            'keep_archives': True,
+            'reply_to_mode': 'email',
+            'reply_to': self.email_reply_to,
+        })
+        self.assertEqual(self.mailing_list_1.contact_ids.message_ids, self.env['mail.message'])
+
+        with self.mock_mail_gateway(mail_unlink_sent=True):
+            mailing.action_send_mail()
+
+        self.assertEqual(len(self._mails), 3)
+        self.assertEqual(len(self._new_mails.exists()), 3)
+        self.assertEqual(len(self.mailing_list_1.contact_ids.message_ids), 3)
+
+        # 2- Keep archives and reply-to set to 'answer = update thread'
+        self.mailing_list_1.contact_ids.message_ids.unlink()
+        mailing = mailing.copy()
+        mailing.write({
+            'reply_to_mode': 'thread',
+        })
+        self.assertEqual(self.mailing_list_1.contact_ids.message_ids, self.env['mail.message'])
+
+        with self.mock_mail_gateway(mail_unlink_sent=True):
+            mailing.action_send_mail()
+
+        self.assertEqual(len(self._mails), 3)
+        self.assertEqual(len(self._new_mails.exists()), 3)
+        self.assertEqual(len(self.mailing_list_1.contact_ids.message_ids), 3)
+
+        # 3- Remove archives and reply-to set to 'answer = new thread'
+        self.mailing_list_1.contact_ids.message_ids.unlink()
+        mailing = mailing.copy()
+        mailing.write({
+            'keep_archives': False,
+            'reply_to_mode': 'email',
+            'reply_to': self.email_reply_to,
+        })
+        self.assertEqual(self.mailing_list_1.contact_ids.message_ids, self.env['mail.message'])
+
+        with self.mock_mail_gateway(mail_unlink_sent=True):
+            mailing.action_send_mail()
+
+        self.assertEqual(len(self._mails), 3)
+        self.assertEqual(len(self._new_mails.exists()), 0)
+        self.assertEqual(self.mailing_list_1.contact_ids.message_ids, self.env['mail.message'])
+
+        # 4- Remove archives and reply-to set to 'answer = update thread'
+        # Imply keeping mail.message for gateway reply)
+        self.mailing_list_1.contact_ids.message_ids.unlink()
+        mailing = mailing.copy()
+        mailing.write({
+            'keep_archives': False,
+            'reply_to_mode': 'thread',
+        })
+        self.assertEqual(self.mailing_list_1.contact_ids.message_ids, self.env['mail.message'])
+
+        with self.mock_mail_gateway(mail_unlink_sent=True):
+            mailing.action_send_mail()
+
+        self.assertEqual(len(self._mails), 3)
+        self.assertEqual(len(self._new_mails.exists()), 0)
+        self.assertEqual(len(self.mailing_list_1.contact_ids.message_ids), 3)
+
     @users('user_marketing')
     @mute_logger('odoo.addons.mail.models.mail_mail')
     def test_mailing_on_res_partner(self):