diff --git a/addons/mail/tests/__init__.py b/addons/mail/tests/__init__.py
index e56729715bd..16748da1302 100644
--- a/addons/mail/tests/__init__.py
+++ b/addons/mail/tests/__init__.py
@@ -4,6 +4,7 @@
 from . import test_mail_channel
 from . import test_mail_channel_as_guest
 from . import test_mail_channel_partner
+from . import test_mail_composer
 from . import test_mail_full_composer
 from . import test_mail_render
 from . import test_mail_template
diff --git a/addons/mail/tests/test_mail_composer.py b/addons/mail/tests/test_mail_composer.py
new file mode 100644
index 00000000000..8dd6c5614f1
--- /dev/null
+++ b/addons/mail/tests/test_mail_composer.py
@@ -0,0 +1,84 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+
+from odoo.tests import users
+from odoo.addons.mail.tests.common import MailCommon
+
+
+class TestMailComposer(MailCommon):
+    @classmethod
+    def setUpClass(cls):
+        super(TestMailComposer, cls).setUpClass()
+        cls.env['ir.config_parameter'].set_param('mail.restrict.template.rendering', True)
+        cls.user_employee.groups_id -= cls.env.ref('mail.group_mail_template_editor')
+        cls.test_record = cls.env['res.partner'].with_context(cls._test_context).create({
+            'name': 'Test',
+        })
+        cls.body_html = """<div>
+    <h1>Hello sir!</h1>
+    <p>Here! <a href="https://www.example.com">
+        <!--[if mso]>
+            <i style="letter-spacing: 25px; mso-font-width: -100%; mso-text-raise: 30pt;">&nbsp;</i>
+        <![endif]-->
+        A link for you!
+        <!--[if mso]>
+            <i style="letter-spacing: 25px; mso-font-width: -100%;">&nbsp;</i>
+        <![endif]-->
+    </a> Make good use of it.</p>
+</div>"""
+
+        cls.mail_template = cls.env['mail.template'].create({
+            'name': 'Test template with mso conditionals',
+            'subject': 'MSO FTW',
+            'body_html': cls.body_html,
+            'lang': '{{ object.lang }}',
+            'auto_delete': True,
+            'model_id': cls.env.ref('base.model_res_partner').id,
+        })
+
+    @users('employee')
+    def test_mail_mass_mode_template_with_mso(self):
+        mail_compose_message = self.env['mail.compose.message'].create({
+            'composition_mode': 'mass_mail',
+            'model': 'res.partner',
+            'template_id': self.mail_template.id,
+            'subject': 'MSO FTW',
+        })
+
+        values = mail_compose_message.get_mail_values(self.partner_employee.ids)
+
+        self.assertIn("""<div>
+    <h1>Hello sir!</h1>
+    <p>Here! <a href="https://www.example.com">
+        A link for you!
+    </a> Make good use of it.</p>
+</div>""",
+            values[self.partner_employee.id]['body_html'],
+            'We must remove comments')
+
+    @users('employee')
+    def test_mail_mass_mode_compose_with_mso(self):
+        composer = self.env['mail.compose.message'].with_context({
+            'default_model': self.test_record._name,
+            'default_composition_mode': 'mass_mail',
+            'active_ids': [self.test_record.id],
+            'active_model': self.test_record._name,
+            'active_id': self.test_record.id
+        }).create({
+            'body': self.body_html,
+            'partner_ids': [(4, self.partner_employee.id)],
+            'composition_mode': 'mass_mail',
+        })
+        with self.mock_mail_gateway(mail_unlink_sent=True):
+            composer._action_send_mail()
+
+        values = composer.get_mail_values(self.partner_employee.ids)
+
+        self.assertIn("""<div>
+    <h1>Hello sir!</h1>
+    <p>Here! <a href="https://www.example.com">
+        A link for you!
+    </a> Make good use of it.</p>
+</div>""",
+            values[self.partner_employee.id]['body_html'],
+            'We must remove comments')