diff --git a/addons/mail/tests/common.py b/addons/mail/tests/common.py
index 004b2a959ae..26fbd22c4d3 100644
--- a/addons/mail/tests/common.py
+++ b/addons/mail/tests/common.py
@@ -501,12 +501,22 @@ class MockEmail(common.BaseCase, MockSmtplibCase):
         expected['email_to'] = email_to_list
 
         # fetch mail
-        sent_mail = next(
-            (mail for mail in self._mails
-             if set(mail['email_to']) == set(expected['email_to']) and mail['email_from'] == expected['email_from']
-             ), False)
-        debug_info = '-'.join('From: %s-To: %s' % (mail['email_from'], mail['email_to']) for mail in self._mails) if not bool(sent_mail) else ''
-        self.assertTrue(bool(sent_mail), 'Expected mail from %s to %s not found in %s' % (expected['email_from'], expected['email_to'], debug_info))
+        sent_mails = [
+            mail for mail in self._mails
+            if set(mail['email_to']) == set(expected['email_to']) and mail['email_from'] == expected['email_from']
+        ]
+        if len(sent_mails) > 1 and values.get('subject'):
+            # try to better filter
+            sent_mail = next((mail for mail in sent_mails if mail['subject'] == values['subject']), False)
+        else:
+            sent_mail = sent_mails[0] if sent_mails else False
+        debug_info = ''
+        if not sent_mail:
+            debug_info = '-'.join('From: %s-To: %s' % (mail['email_from'], mail['email_to']) for mail in self._mails)
+        self.assertTrue(
+            bool(sent_mail),
+            'Expected mail from %s to %s not found in %s' % (expected['email_from'], expected['email_to'], debug_info)
+        )
 
         # assert values
         for val in direct_check:
diff --git a/addons/test_mail/data/mail_template_data.xml b/addons/test_mail/data/mail_template_data.xml
index 45452973061..944a1b7a95f 100644
--- a/addons/test_mail/data/mail_template_data.xml
+++ b/addons/test_mail/data/mail_template_data.xml
@@ -34,7 +34,7 @@
     </template>
 
     <template id="mail_template_simple_test">
-        <p>Hello <t t-out="partner.name"/>,</p>
+        <p>Hello <t t-out="partner.name"/>, this comes from <t t-out="object.name"/>.</p>
     </template>
 
 </odoo>
diff --git a/addons/test_mail/models/test_mail_models.py b/addons/test_mail/models/test_mail_models.py
index 6b3222b6d89..8b3eec16f95 100644
--- a/addons/test_mail/models/test_mail_models.py
+++ b/addons/test_mail/models/test_mail_models.py
@@ -50,6 +50,16 @@ class MailTestGatewayGroups(models.Model):
             values['alias_parent_thread_id'] = self.id
         return values
 
+    def _message_get_default_recipients(self):
+        return dict(
+            (record.id, {
+                'email_cc': False,
+                'email_to': record.email_from if not record.customer_id.ids else False,
+                'partner_ids': record.customer_id.ids,
+            })
+            for record in self
+        )
+
 
 class MailTestStandard(models.Model):
     """ This model can be used in tests when automatic subscription and simple
@@ -105,6 +115,16 @@ class MailTestTicket(models.Model):
     user_id = fields.Many2one('res.users', 'Responsible', tracking=1)
     container_id = fields.Many2one('mail.test.container', tracking=True)
 
+    def _message_get_default_recipients(self):
+        return dict(
+            (record.id, {
+                'email_cc': False,
+                'email_to': record.email_from if not record.customer_id.ids else False,
+                'partner_ids': record.customer_id.ids,
+            })
+            for record in self
+        )
+
     def _notify_get_recipients_groups(self, msg_vals=None):
         """ Activate more groups to test query counters notably (and be backward
         compatible for tests). """
@@ -163,6 +183,16 @@ class MailTestContainer(models.Model):
         'mail.alias', 'Alias',
         delegate=True)
 
+    def _message_get_default_recipients(self):
+        return dict(
+            (record.id, {
+                'email_cc': False,
+                'email_to': False,
+                'partner_ids': record.customer_id.ids,
+            })
+            for record in self
+        )
+
     def _notify_get_recipients_groups(self, msg_vals=None):
         """ Activate more groups to test query counters notably (and be backward
         compatible for tests). """
diff --git a/addons/test_mail/tests/test_message_post.py b/addons/test_mail/tests/test_message_post.py
index 102191babb5..7341c9fd44a 100644
--- a/addons/test_mail/tests/test_message_post.py
+++ b/addons/test_mail/tests/test_message_post.py
@@ -412,12 +412,20 @@ class TestMessageNotify(TestMessagePostCommon):
 
 
 @tagged('mail_post')
-class TestMessagePost(TestMessagePostCommon, CronMixinCase):
+class TestMessageLog(TestMessagePostCommon):
 
-    def test_initial_values(self):
-        self.assertFalse(self.test_record.message_ids)
-        self.assertFalse(self.test_record.message_follower_ids)
-        self.assertFalse(self.test_record.message_partner_ids)
+    @classmethod
+    def setUpClass(cls):
+        super(TestMessageLog, cls).setUpClass()
+        # ensure employee can create partners, necessary for templates
+        cls.user_employee.write({
+            'groups_id': [(4, cls.env.ref('base.group_partner_manager').id)],
+        })
+
+        cls.test_records, cls.test_partners = cls._create_records_for_batch(
+            'mail.test.ticket',
+            10,
+        )
 
     @users('employee')
     def test_message_log(self):
@@ -442,6 +450,67 @@ class TestMessagePost(TestMessagePostCommon, CronMixinCase):
             }
         )
 
+    @users('employee')
+    def test_message_log_batch(self):
+        test_records = self.test_records.with_env(self.env)
+        test_records.message_subscribe(self.partner_employee_2.ids)
+
+        new_notes = test_records._message_log_batch(
+            bodies=dict(
+                (test_record.id, '<p>Test _message_log_batch</p>')
+                for test_record in test_records
+            ),
+        )
+        for test_record, new_note in zip(test_records, new_notes):
+            self.assertMessageFields(
+                new_note,
+                {'author_id': self.partner_employee,
+                 'body': '<p>Test _message_log_batch</p>',
+                 'email_from': formataddr((self.partner_employee.name, self.partner_employee.email_normalized)),
+                 'is_internal': True,
+                 'message_type': 'notification',
+                 'model': test_record._name,
+                 'notified_partner_ids': self.env['res.partner'],
+                 'reply_to': formataddr((self.company_admin.name, '%s@%s' % (self.alias_catchall, self.alias_domain))),
+                 'res_id': test_record.id,
+                 'subtype_id': self.env.ref('mail.mt_note'),
+                }
+            )
+
+    @users('employee')
+    def test_message_log_with_view(self):
+        test_records = self.test_records.with_env(self.env)
+        test_records.message_subscribe(self.partner_employee_2.ids)
+
+        new_notes = test_records._message_log_with_view(
+            'test_mail.mail_template_simple_test',
+            values={'partner': self.user_employee.partner_id}
+        )
+        for test_record, new_note in zip(test_records, new_notes):
+            self.assertMessageFields(
+                new_note,
+                {'author_id': self.partner_employee,
+                 'body': f'<p>Hello {self.user_employee.name}, this comes from {test_record.name}.</p>',
+                 'email_from': formataddr((self.partner_employee.name, self.partner_employee.email_normalized)),
+                 'is_internal': True,
+                 'message_type': 'notification',
+                 'model': test_record._name,
+                 'notified_partner_ids': self.env['res.partner'],
+                 'reply_to': formataddr((self.company_admin.name, '%s@%s' % (self.alias_catchall, self.alias_domain))),
+                 'res_id': test_record.id,
+                 'subtype_id': self.env.ref('mail.mt_note'),
+                }
+            )
+
+
+@tagged('mail_post')
+class TestMessagePost(TestMessagePostCommon, CronMixinCase):
+
+    def test_initial_values(self):
+        self.assertFalse(self.test_record.message_ids)
+        self.assertFalse(self.test_record.message_follower_ids)
+        self.assertFalse(self.test_record.message_partner_ids)
+
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink')
     @users('employee')
     def test_message_post(self):
@@ -508,6 +577,37 @@ class TestMessagePost(TestMessagePostCommon, CronMixinCase):
                 partner_ids=self.partner_portal.ids,
             )
 
+    @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink')
+    @users('employee')
+    def test_message_post_defaults(self):
+        """ Test default values when posting a classic message. """
+        test_record = self.env['mail.test.simple'].create([{'name': 'Defaults'}])
+        creation_msg = test_record.message_ids
+        self.assertEqual(len(creation_msg), 1)
+
+        with self.mock_mail_app():
+            new_message = test_record.message_post(
+                body='Body',
+                partner_ids=[self.partner_employee_2.id],
+            )
+
+        self.assertMessageFields(
+            new_message,
+            {'author_id': self.partner_employee,
+             'body': '<p>Body</p>',
+             'email_from': formataddr((self.partner_employee.name, self.partner_employee.email_normalized)),
+             'is_internal': False,
+             'message_type': 'notification',
+             'model': test_record._name,
+             'notified_partner_ids': self.partner_employee_2,
+             'parent_id': creation_msg,
+             'record_name': test_record.name,
+             'reply_to': formataddr((f'{self.company_admin.name} {test_record.name}', f'{self.alias_catchall}@{self.alias_domain}')),
+             'res_id': test_record.id,
+             'subtype_id': self.env.ref('mail.mt_note'),
+            }
+        )
+
     @users('employee')
     def test_message_post_inactive_follower(self):
         """ Test posting with inactive followers does not notify them (e.g. odoobot) """
@@ -854,100 +954,202 @@ class TestMessagePostHelpers(TestMessagePostCommon):
             'groups_id': [(4, cls.env.ref('base.group_partner_manager').id)],
         })
 
+        cls.user_employee.write({
+            'groups_id': [(4, cls.env.ref('base.group_partner_manager').id)],
+        })
+
+        cls.test_records, cls.test_partners = cls._create_records_for_batch(
+            'mail.test.ticket',
+            10,
+        )
+
     @users('employee')
-    def test_message_log_with_view(self):
-        test_record = self.env['mail.test.simple'].browse(self.test_record.ids)
-        new_note = test_record._message_log_with_view(
-            'test_mail.mail_template_simple_test',
-            values={'partner': self.user_employee.partner_id}
-        )
-        self.assertMessageFields(
-            new_note,
-            {'author_id': self.partner_employee,
-             'body': '<p>Hello %s,</p>' % self.user_employee.name,
-             'email_from': formataddr((self.partner_employee.name, self.partner_employee.email_normalized)),
-             'is_internal': True,
-             'message_type': 'notification',
-             'model': test_record._name,
-             'notified_partner_ids': self.env['res.partner'],
-             'reply_to': formataddr((self.company_admin.name, '%s@%s' % (self.alias_catchall, self.alias_domain))),
-             'res_id': test_record.id,
-             'subtype_id': self.env.ref('mail.mt_note'),
-            }
-        )
-
     @mute_logger('odoo.addons.mail.models.mail_mail')
-    def test_message_post_w_template(self):
-        test_record = self.env['mail.test.simple'].with_context(self._test_context).create({'name': 'Test', 'email_from': 'ignasse@example.com'})
-
+    def test_message_mail_with_template(self):
+        """ Test sending mass mail on documents based on a template """
         _attachments = self._generate_attachments_data(count=2, res_id=0, res_model='mail.template')
         email_1 = 'test1@example.com'
         email_2 = 'test2@example.com'
-        email_3 = self.partner_1.email
-        template = self._create_template('mail.test.simple', {
+        template = self._create_template('mail.test.ticket', {
             'attachment_ids': [(0, 0, attach_vals) for attach_vals in _attachments],
-            'partner_to': '%s,%s' % (self.partner_2.id, self.user_admin.partner_id.id),
-            'email_to': '%s, %s' % (email_1, email_2),
-            'email_cc': '%s' % email_3,
+            'auto_delete': True,
+            # After the HTML sanitizer, it will become "<p>Body for: <t t-out="object.name" /><a href="">link</a></p>"
+            'body_html': 'Body for: <t t-out="object.name" /><script>test</script><a href="javascript:alert(1)">link</a>',
+            'email_cc': self.partner_1.email,
+            'email_to': f'{email_1}, {email_2}',
+            'partner_to': '{{ object.customer_id.id }},%s' % self.partner_2.id,
         })
         template.attachment_ids.write({'res_id': template.id})
 
-        # admin should receive emails
-        self.user_admin.write({'notification_type': 'email'})
+        test_records = self.test_records.with_env(self.env)
+        with self.mock_mail_gateway():
+            _new_mails, _new_messages = test_records.with_user(self.user_employee).message_post_with_template(
+                template.id,
+                composition_mode='mass_mail',
+            )
+
+        # created partners from inline email addresses
+        new_partners = self.env['res.partner'].search([('email', 'in', (email_1, email_2))])
+        self.assertEqual(len(new_partners), 2,
+                         'Post with template: should have created partners based on template emails')
+
+        # sent emails (mass mail mode)
+        for test_record in test_records:
+            self.assertMailMail(
+                new_partners + self.partner_1 + self.partner_2 + test_record.customer_id,
+                'sent',
+                author=self.user_employee.partner_id,
+                email_values={
+                    'attachments': [
+                        ('AttFileName_00.txt', b'AttContent_00', 'text/plain'),
+                        ('AttFileName_01.txt', b'AttContent_01', 'text/plain'),
+                    ],
+                    'subject': f'About {test_record.name}',
+                    'body_content': test_record.name,
+                },
+                fields_values={
+                    'auto_delete': True,
+                    'is_internal': False,
+                    'is_notification': True,  # not auto_delete_message -> keep underlying mail.message
+                    'message_type': 'email',
+                    'model': test_record._name,
+                    'notified_partner_ids': self.env['res.partner'],
+                    'to_delete': True,
+                    'subtype_id': self.env['mail.message.subtype'],
+                    'reply_to': formataddr((f'{self.company_admin.name} {test_record.name}', f'{self.alias_catchall}@{self.alias_domain}')),
+                    'res_id': test_record.id,
+                }
+            )
+
+    @users('employee')
+    @mute_logger('odoo.addons.mail.models.mail_mail')
+    def test_message_mail_with_view(self):
+        """ Test sending a mass mailing on documents based on a view """
+        test_records = self.test_records.with_env(self.env)
+        for test_record in test_records:
+            test_record.message_subscribe(test_record.customer_id.ids)
+
+        with self.mock_mail_gateway():
+            res_messages = test_records.message_post_with_view(
+                'test_mail.mail_template_simple_test',
+                values={'partner': self.user_employee.partner_id},
+                composition_mode='mass_mail',
+                subject='About mass mailing',
+            )
+        self.assertEqual(len(res_messages), 0)
+        self.assertEqual(len(self._new_mails), 10)
+
+        # sent emails (mass mail mode)
+        for test_record in test_records:
+            self.assertMailMail(
+                [test_record.customer_id], 'sent',
+                author=self.user_employee.partner_id,
+                email_values={
+                    'body_content': f'<p>Hello {self.user_employee.partner_id.name}, this comes from {test_record.name}.</p>',
+                    'subject': 'About mass mailing',
+                },
+                fields_values={
+                    'auto_delete': False,
+                    'is_internal': False,
+                    'is_notification': True,  # not auto_delete_message -> keep underlying mail.message
+                    'message_type': 'email',
+                    'model': test_record._name,
+                    'notified_partner_ids': self.env['res.partner'],
+                    'recipient_ids': test_record.customer_id,
+                    'to_delete': False,
+                    'subtype_id': self.env['mail.message.subtype'],
+                    'reply_to': formataddr((f'{self.company_admin.name} {test_record.name}', f'{self.alias_catchall}@{self.alias_domain}')),
+                    'res_id': test_record.id,
+                }
+            )
+
+    @users('employee')
+    @mute_logger('odoo.addons.mail.models.mail_mail')
+    def test_message_post_with_template(self):
+        """ Test posting on a document based on a template content """
+        _attachments = self._generate_attachments_data(count=2, res_id=0, res_model='mail.template')
+        email_1 = 'test1@example.com'
+        email_2 = 'test2@example.com'
+        template = self._create_template('mail.test.ticket', {
+            'attachment_ids': [(0, 0, attach_vals) for attach_vals in _attachments],
+            'auto_delete': True,
+            'email_cc': self.partner_1.email,
+            'email_to': f'{email_1}, {email_2}',
+            'partner_to': '{{ object.customer_id.id }},%s' % self.partner_2.id,
+        })
+        template.attachment_ids.write({'res_id': template.id})
         # Force the attachments of the template to be in the natural order.
         self.email_template.invalidate_recordset(['attachment_ids'])
 
+        test_record = self.test_records.with_env(self.env)[0]
+        test_record.message_subscribe(test_record.customer_id.ids)
         with self.mock_mail_gateway():
-            test_record.with_user(self.user_employee).message_post_with_template(self.email_template.id, composition_mode='comment')
+            _new_mail, new_message = test_record.with_user(self.user_employee).message_post_with_template(
+                self.email_template.id,
+                composition_mode='comment'
+            )
 
+        # created partners from inline email addresses
         new_partners = self.env['res.partner'].search([('email', 'in', [email_1, email_2])])
-        for r in [self.partner_1, self.partner_2, new_partners[0], new_partners[1], self.partner_admin]:
-            self.assertSentEmail(
-                self.user_employee.partner_id,
-                [r],
-                subject='About %s' % test_record.name,
-                body_content=test_record.name,
-                attachments=[
-                    ('AttFileName_00.txt', b'AttContent_00', 'text/plain'),
-                    ('AttFileName_01.txt', b'AttContent_01', 'text/plain'),
-                ]
-            )
+        self.assertEqual(len(new_partners), 2,
+                         'Post with template: should have created partners based on template emails')
 
-    @mute_logger('odoo.addons.mail.models.mail_mail')
-    def test_message_post_w_template_mass_mode(self):
-        test_record = self.env['mail.test.simple'].with_context(self._test_context).create({'name': 'Test', 'email_from': 'ignasse@example.com'})
-        self.user_employee.write({
-            'groups_id': [(4, self.env.ref('base.group_partner_manager').id)],
-        })
+        # check notifications have been sent
+        self.assertMailNotifications(new_message, [{
+            'content': f'<p>Hello {test_record.name}</p>',
+            'message_type': 'notification',
+            'notif': [
+                {'partner': self.partner_1, 'type': 'email'},
+                {'partner': self.partner_2, 'type': 'email'},
+                {'partner': new_partners[0], 'type': 'email'},
+                {'partner': new_partners[1], 'type': 'email'},
+                {'partner': test_record.customer_id, 'type': 'email'},
+            ],
+            'subtype': 'mail.mt_comment',
+        }])
+        self.assertMessageFields(
+            new_message,
+            {'author_id': self.partner_employee,
+             'email_from': formataddr((self.partner_employee.name, self.partner_employee.email_normalized)),
+             'is_internal': False,
+             'model': test_record._name,
+             'reply_to': formataddr((f'{self.company_admin.name} {test_record.name}', f'{self.alias_catchall}@{self.alias_domain}')),
+             'res_id': test_record.id,
+            }
+        )
 
-        _attachments = self._generate_attachments_data(count=2, res_id=0, res_model='mail.template')
-        template = self._create_template('mail.test.simple', {
-            'attachment_ids': [(0, 0, attach_vals) for attach_vals in _attachments],
-            # After the HTML sanitizer, it will become "<p>Body for: <t t-out="object.name" /><a href="">link</a></p>"
-            'body_html': 'Body for: <t t-out="object.name" /><script>test</script><a href="javascript:alert(1)">link</a>',
-            'email_to': 'test@example.com',
-            'email_cc': self.partner_1.email,
-            'partner_to': '%s,%s' % (self.partner_2.id, self.user_admin.partner_id.id),
-        })
-        template.attachment_ids.write({'res_id': template.id})
+    @users('employee')
+    @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.tests')
+    def test_message_post_with_view(self):
+        """ Test posting on documents based on a view """
+        test_record = self.test_records.with_env(self.env)[0]
+        test_record.message_subscribe(test_record.customer_id.ids)
 
         with self.mock_mail_gateway():
-            test_record.with_user(self.user_employee).message_post_with_template(
-                template.id,
-                composition_mode='mass_mail'
+            new_message = test_record.message_post_with_view(
+                'test_mail.mail_template_simple_test',
+                values={'partner': self.user_employee.partner_id}
             )
 
-        new_partner = self.env['res.partner'].search([('email', '=', 'test@example.com')])
-
-        self.assertSentEmail(
-            self.user_employee.partner_id,
-            [new_partner],
-            subject='About %s' % test_record.name,
-            body_content=test_record.name,
-            attachments=[
-                ('AttFileName_00.txt', b'AttContent_00', 'text/plain'),
-                ('AttFileName_01.txt', b'AttContent_01', 'text/plain'),
-            ]
+        # check notifications have been sent
+        self.assertMailNotifications(new_message, [{
+            'content': f'<p>Hello {self.user_employee.partner_id.name}, this comes from {test_record.name}.</p>',
+            'message_type': 'notification',
+            'notif': [
+                {'partner': test_record.customer_id, 'type': 'email'},
+            ],
+            'subtype': 'mail.mt_comment',
+        }])
+        self.assertMessageFields(
+            new_message,
+            {'author_id': self.partner_employee,
+             'email_from': formataddr((self.partner_employee.name, self.partner_employee.email_normalized)),
+             'is_internal': False,
+             'message_type': 'notification',
+             'model': test_record._name,
+             'reply_to': formataddr((f'{self.company_admin.name} {test_record.name}', f'{self.alias_catchall}@{self.alias_domain}')),
+             'res_id': test_record.id,
+            }
         )
 
 
diff --git a/addons/test_mail/tests/test_performance.py b/addons/test_mail/tests/test_performance.py
index a4f74b4ba6f..2d3d8ef92bc 100644
--- a/addons/test_mail/tests/test_performance.py
+++ b/addons/test_mail/tests/test_performance.py
@@ -19,6 +19,13 @@ class BaseMailPerformance(MailCommon, TransactionCaseWithUserDemo):
 
         # creating partners is required notably witn template usage
         cls.user_employee.write({'groups_id': [(4, cls.env.ref('base.group_partner_manager').id)]})
+        cls.user_test = cls.env['res.users'].with_context(cls._test_context).create({
+            'name': 'Paulette Testouille',
+            'login': 'paul',
+            'email': 'user.test.paulette@example.com',
+            'notification_type': 'inbox',
+            'groups_id': [(6, 0, [cls.env.ref('base.group_user').id])],
+        })
 
         cls.customer = cls.env['res.partner'].with_context(cls._test_context).create({
             'country_id': cls.env.ref('base.be').id,
@@ -37,6 +44,57 @@ class BaseMailPerformance(MailCommon, TransactionCaseWithUserDemo):
         self.patch(self.env.registry, 'ready', True)
         self.flush_tracking()
 
+    def _create_test_records(self):
+        test_record_full = self.env['mail.test.ticket'].with_context(self._test_context).create({
+            'name': 'TestRecord',
+            'customer_id': self.customer.id,
+            'user_id': self.user_test.id,
+            'email_from': 'nopartner.test@example.com',
+        })
+        test_template_full = self.env['mail.template'].create({
+            'name': 'TestTemplate',
+            'model_id': self.env['ir.model']._get('mail.test.ticket').id,
+            'subject': 'About {{ object.name }}',
+            'body_html': '<p>Hello <t t-out="object.name"/></p>',
+            'email_from': '{{ object.user_id.email_formatted }}',
+            'partner_to': '{{ object.customer_id.id }}',
+            'email_to': '{{ ("%s Customer <%s>" % (object.name, object.email_from)) }}',
+            'attachment_ids': [
+                (0, 0, dict(attachment, res_model='mail.template'))
+                for attachment in self.test_attachments_vals
+            ],
+        })
+        self.flush_tracking()
+        return test_record_full, test_template_full
+
+    def _create_test_records_for_batch(self):
+        test_partners = self.env['res.partner'].create([{
+            'phone': f'0485{idx}{idx}1122',
+            'email': f'test.customer.{idx}@test.example.com',
+            'name': f'Test Customer {idx}',
+        } for idx in range(0, 10)])
+        test_records = self.env['mail.test.ticket'].create([{
+            'customer_id': test_partners[idx].id,
+            'email_from': test_partners[idx].email_formatted,
+            'name': f'Test Ticket {idx}',
+            'user_id': self.user_test.id,
+        } for idx in range(0, 10)])
+        test_template_full = self.env['mail.template'].create({
+            'name': 'TestTemplate',
+            'model_id': self.env['ir.model']._get('mail.test.ticket').id,
+            'subject': 'About {{ object.name }}',
+            'body_html': '<p>Hello <t t-out="object.name"/></p>',
+            'email_from': '{{ object.user_id.email_formatted }}',
+            'partner_to': '{{ object.customer_id.id }}',
+            'email_to': '{{ ("%s Customer <%s>" % (object.name, object.email_from)) }}',
+            'attachment_ids': [
+                (0, 0, dict(attachment, res_model='mail.template'))
+                for attachment in self.test_attachments_vals
+            ],
+        })
+        self.flush_tracking()
+        return test_partners, test_records, test_template_full
+
 
 @tagged('mail_performance', 'post_install', '-at_install')
 class TestBaseMailPerformance(BaseMailPerformance):
@@ -184,38 +242,10 @@ class TestMailAPIPerformance(BaseMailPerformance):
 
     def setUp(self):
         super(TestMailAPIPerformance, self).setUp()
-        self.user_test = self.env['res.users'].with_context(self._test_context).create({
-            'name': 'Paulette Testouille',
-            'login': 'paul',
-            'email': 'user.test.paulette@example.com',
-            'notification_type': 'inbox',
-            'groups_id': [(6, 0, [self.env.ref('base.group_user').id])],
-        })
 
         # automatically follow activities, for backward compatibility concerning query count
         self.env.ref('mail.mt_activities').write({'default': True})
 
-    def _create_test_records(self):
-        self.test_record_full = self.env['mail.test.ticket'].with_context(self._test_context).create({
-            'name': 'TestRecord',
-            'customer_id': self.customer.id,
-            'user_id': self.user_test.id,
-            'email_from': 'nopartner.test@example.com',
-        })
-        self.test_template_full = self.env['mail.template'].create({
-            'name': 'TestTemplate',
-            'model_id': self.env['ir.model']._get('mail.test.ticket').id,
-            'subject': 'About {{ object.name }}',
-            'body_html': '<p>Hello <t t-out="object.name"/></p>',
-            'email_from': '{{ object.user_id.email_formatted }}',
-            'partner_to': '{{ object.customer_id.id }}',
-            'email_to': '{{ ("%s Customer <%s>" % (object.name, object.email_from)) }}',
-            'attachment_ids': [
-                (0, 0, dict(attachment, res_model='mail.template'))
-                for attachment in self.test_attachments_vals
-            ],
-        })
-
     @users('__system__', 'employee')
     @warmup
     def test_adv_activity(self):
@@ -300,8 +330,7 @@ class TestMailAPIPerformance(BaseMailPerformance):
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer(self):
-        self._create_test_records()
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
+        test_record, _test_template = self._create_test_records()
         customer_id = self.customer.id
         with self.assertQueryCount(__system__=2, employee=2):
             composer = self.env['mail.compose.message'].with_context({
@@ -320,8 +349,7 @@ class TestMailAPIPerformance(BaseMailPerformance):
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer_attachments(self):
-        self._create_test_records()
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
+        test_record, _test_template = self._create_test_records()
         customer = self.env['res.partner'].browse(self.customer.ids)
         attachments = self.env['ir.attachment'].with_user(self.env.user).create(self.test_attachments_vals)
         with self.assertQueryCount(__system__=3, employee=3):
@@ -342,11 +370,10 @@ class TestMailAPIPerformance(BaseMailPerformance):
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer_form_attachments(self):
-        self._create_test_records()
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
+        test_record, _test_template = self._create_test_records()
         customer = self.env['res.partner'].browse(self.customer.ids)
         attachments = self.env['ir.attachment'].with_user(self.env.user).create(self.test_attachments_vals)
-        with self.assertQueryCount(__system__=18, employee=18):  # tm+com 16/16
+        with self.assertQueryCount(__system__=12, employee=12):
             composer_form = Form(
                 self.env['mail.compose.message'].with_context({
                     'default_composition_mode': 'comment',
@@ -368,12 +395,31 @@ class TestMailAPIPerformance(BaseMailPerformance):
         self.assertEqual(message.attachment_ids, attachments)
         self.assertEqual(message.notified_partner_ids, customer + self.user_test.partner_id)
 
+    @users('__system__', 'employee')
+    @warmup
+    @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
+    def test_mail_composer_mass_w_template(self):
+        _partners, test_records, test_template = self._create_test_records_for_batch()
+
+        with self.assertQueryCount(__system__=3, employee=3):
+            composer = self.env['mail.compose.message'].with_context({
+                'active_ids': test_records.ids,
+                'default_composition_mode': 'mass_mail',
+                'default_model': test_records._name,
+                'default_template_id': test_template.id,
+            }).create({})
+            composer._onchange_template_id_wrapper()
+
+        with self.assertQueryCount(__system__=126, employee=159), self.mock_mail_gateway():
+            composer._action_send_mail()
+
+        self.assertEqual(len(self._new_mails), 10)
+
     @users('__system__', 'employee')
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer_nodelete(self):
-        self._create_test_records()
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
+        test_record, _test_template = self._create_test_records()
         customer_id = self.customer.id
         with self.assertQueryCount(__system__=2, employee=2):
             composer = self.env['mail.compose.message'].with_context({
@@ -393,11 +439,8 @@ class TestMailAPIPerformance(BaseMailPerformance):
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer_w_template(self):
-        self._create_test_records()
-        self.test_template_full.write({'attachment_ids': [(5, 0)]})
-
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
-        test_template = self.env['mail.template'].browse(self.test_template_full.id)
+        test_record, test_template = self._create_test_records()
+        test_template.write({'attachment_ids': [(5, 0)]})
 
         with self.assertQueryCount(__system__=23, employee=24):  # tm 13/14 / com 22/23
             composer = self.env['mail.compose.message'].with_context({
@@ -422,10 +465,8 @@ class TestMailAPIPerformance(BaseMailPerformance):
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer_w_template_attachments(self):
-        self._create_test_records()
+        test_record, test_template = self._create_test_records()
 
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
-        test_template = self.env['mail.template'].browse(self.test_template_full.id)
         with self.assertQueryCount(__system__=24, employee=25):  # tm 14/15 / com 23/24
             composer = self.env['mail.compose.message'].with_context({
                 'default_composition_mode': 'comment',
@@ -452,13 +493,11 @@ class TestMailAPIPerformance(BaseMailPerformance):
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer_w_template_form(self):
-        self._create_test_records()
-        self.test_template_full.write({'attachment_ids': [(5, 0)]})
+        test_record, test_template = self._create_test_records()
+        test_template.write({'attachment_ids': [(5, 0)]})
 
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
-        test_template = self.env['mail.template'].browse(self.test_template_full.id)
         customer = self.env['res.partner'].browse(self.customer.ids)
-        with self.assertQueryCount(__system__=40, employee=42):  # tm 28/30 / com 37/39
+        with self.assertQueryCount(__system__=34, employee=36):  # tm 24/26 / com 33/35
             composer_form = Form(
                 self.env['mail.compose.message'].with_context({
                     'default_composition_mode': 'comment',
@@ -485,12 +524,10 @@ class TestMailAPIPerformance(BaseMailPerformance):
     @warmup
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     def test_mail_composer_w_template_form_attachments(self):
-        self._create_test_records()
+        test_record, test_template = self._create_test_records()
 
-        test_record = self.env['mail.test.ticket'].browse(self.test_record_full.id)
-        test_template = self.env['mail.template'].browse(self.test_template_full.id)
         customer = self.env['res.partner'].browse(self.customer.ids)
-        with self.assertQueryCount(__system__=41, employee=43):  # tm 29/31 / com 38/40
+        with self.assertQueryCount(__system__=35, employee=37):  # tm 25/27 / com 34/36
             composer_form = Form(
                 self.env['mail.compose.message'].with_context({
                     'default_composition_mode': 'comment',
@@ -546,6 +583,36 @@ class TestMailAPIPerformance(BaseMailPerformance):
                 body='<p>Test _message_log</p>',
                 message_type='comment')
 
+    @users('__system__', 'employee')
+    @warmup
+    def test_message_log_batch(self):
+        records = self.env['mail.test.simple'].create([
+            {'name': f'Test_{idx}'}
+            for idx in range(10)
+        ])
+
+        with self.assertQueryCount(__system__=1, employee=1):
+            records._message_log_batch(
+                bodies=dict(
+                    (record.id, '<p>Test _message_log</p>')
+                    for record in records
+                ),
+                message_type='comment')
+
+    @users('__system__', 'employee')
+    @warmup
+    def test_message_log_with_view(self):
+        records = self.env['mail.test.simple'].create([
+            {'name': f'Test_{idx}'}
+            for idx in range(10)
+        ])
+
+        with self.assertQueryCount(__system__=11, employee=11):
+            records._message_log_with_view(
+                'test_mail.mail_template_simple_test',
+                values={'partner': self.customer.with_env(self.env)}
+            )
+
     @users('__system__', 'employee')
     @warmup
     def test_message_log_with_post(self):
@@ -575,7 +642,7 @@ class TestMailAPIPerformance(BaseMailPerformance):
     def test_message_post_one_email_notification(self):
         record = self.env['mail.test.simple'].create({'name': 'Test'})
 
-        with self.assertQueryCount(__system__=24, employee=28):
+        with self.assertQueryCount(__system__=24, employee=27):
             record.message_post(
                 body='<p>Test Post Performances with an email ping</p>',
                 partner_ids=self.customer.ids,
@@ -793,6 +860,29 @@ class TestMailComplexPerformance(BaseMailPerformance):
         self.assertEqual(record.message_ids[0].body, '<p>Adding stuff on %s</p>' % record.name)
         self.assertEqual(record.message_ids[0].notified_partner_ids, self.partners | self.user_portal.partner_id | self.customer)
 
+    @mute_logger('odoo.tests', 'odoo.addons.mail.models.mail_mail', 'odoo.models.unlink')
+    @users('__system__', 'employee')
+    @warmup
+    def test_complex_message_post_view(self):
+        _partners, test_records, test_template = self._create_test_records_for_batch()
+
+        with self.assertQueryCount(__system__=3, employee=3):
+            composer = self.env['mail.compose.message'].with_context({
+                'active_ids': test_records.ids,
+                'default_composition_mode': 'mass_mail',
+                'default_model': test_records._name,
+                'default_template_id': test_template.id,
+            }).create({})
+            composer._onchange_template_id_wrapper()
+
+        with self.assertQueryCount(__system__=121, employee=141):
+            messages_as_sudo = test_records.message_post_with_view(
+                'test_mail.mail_template_simple_test',
+                values={'partner': self.user_test.partner_id},
+            )
+
+        self.assertEqual(len(messages_as_sudo), 10)
+
     @mute_logger('odoo.tests', 'odoo.addons.mail.models.mail_mail', 'odoo.models.unlink')
     @users('__system__', 'employee')
     @warmup