diff --git a/addons/website/controllers/form.py b/addons/website/controllers/form.py
index 5c87a5b68b0..3303671a4d8 100644
--- a/addons/website/controllers/form.py
+++ b/addons/website/controllers/form.py
@@ -4,14 +4,15 @@
 import base64
 import json
 
+from markupsafe import Markup
 from psycopg2 import IntegrityError
 from werkzeug.exceptions import BadRequest
 
 from odoo import http, SUPERUSER_ID, _
+from odoo.addons.base.models.ir_qweb_fields import nl2br
 from odoo.http import request
 from odoo.tools import plaintext2html
 from odoo.exceptions import ValidationError, UserError
-from odoo.addons.base.models.ir_qweb_fields import nl2br
 
 
 class WebsiteForm(http.Controller):
@@ -234,14 +235,11 @@ class WebsiteForm(http.Controller):
                 if default_field.ttype == 'html' or model_name == 'mail.mail':
                     custom_content = nl2br(custom_content)
                 record.update({default_field.name: custom_content})
-            else:
-                values = {
-                    'body': nl2br(custom_content),
-                    'model': model_name,
-                    'message_type': 'comment',
-                    'res_id': record.id,
-                }
-                request.env['mail.message'].with_user(SUPERUSER_ID).create(values)
+            elif hasattr(record, '_message_log'):
+                record._message_log(
+                    body=custom_content,
+                    message_type='comment',
+                )
 
         return record.id
 
@@ -269,20 +267,15 @@ class WebsiteForm(http.Controller):
             else:
                 orphan_attachment_ids.append(attachment_id.id)
 
-        if model_name != 'mail.mail':
+        if model_name != 'mail.mail' and hasattr(record, '_message_log') and orphan_attachment_ids:
             # If some attachments didn't match a field on the model,
             # we create a mail.message to link them to the record
-            if orphan_attachment_ids:
-                values = {
-                    'body': _('<p>Attached files : </p>'),
-                    'model': model_name,
-                    'message_type': 'comment',
-                    'res_id': id_record,
-                    'attachment_ids': [(6, 0, orphan_attachment_ids)],
-                    'subtype_id': request.env['ir.model.data']._xmlid_to_res_id('mail.mt_comment'),
-                }
-                request.env['mail.message'].with_user(SUPERUSER_ID).create(values)
-        else:
+            record._message_log(
+                attachment_ids=[(6, 0, orphan_attachment_ids)],
+                body=Markup(_('<p>Attached files : </p>')),
+                message_type='comment',
+            )
+        elif model_name == 'mail.mail' and orphan_attachment_ids:
             # If the model is mail.mail then we have no other choice but to
             # attach the custom binary field files on the attachment_ids field.
             for attachment_id_id in orphan_attachment_ids:
diff --git a/addons/website_sale/controllers/main.py b/addons/website_sale/controllers/main.py
index 04f840eca29..74a7da3dbbf 100644
--- a/addons/website_sale/controllers/main.py
+++ b/addons/website_sale/controllers/main.py
@@ -4,14 +4,15 @@ from collections import defaultdict
 from itertools import product as cartesian_product
 import json
 import logging
+
 from datetime import datetime
+from markupsafe import Markup
 from werkzeug.exceptions import Forbidden, NotFound
 from werkzeug.urls import url_decode, url_encode, url_parse
 
 from odoo import fields, http, SUPERUSER_ID, tools, _
 from odoo.fields import Command
 from odoo.http import request
-from odoo.addons.base.models.ir_qweb_fields import nl2br
 from odoo.addons.http_routing.models.ir_http import slug
 from odoo.addons.payment import utils as payment_utils
 from odoo.addons.payment.controllers import portal as payment_portal
@@ -113,13 +114,10 @@ class WebsiteSaleForm(WebsiteForm):
             order.write(data['record'])
 
         if data['custom']:
-            values = {
-                'body': nl2br(data['custom']),
-                'model': 'sale.order',
-                'message_type': 'comment',
-                'res_id': order.id,
-            }
-            request.env['mail.message'].with_user(SUPERUSER_ID).create(values)
+            order._message_log(
+                body=data['custom'],
+                message_type='comment',
+            )
 
         if data['attachments']:
             self.insert_attachment(model_record, order.id, data['attachments'])
diff --git a/odoo/addons/base/tests/test_mail.py b/odoo/addons/base/tests/test_mail.py
index e3be6e0d812..b4e91e0fa2b 100644
--- a/odoo/addons/base/tests/test_mail.py
+++ b/odoo/addons/base/tests/test_mail.py
@@ -1,8 +1,8 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-
 from unittest.mock import patch
+
 import email.policy
 import email.message
 import re