diff --git a/addons/website_form/controllers/main.py b/addons/website_form/controllers/main.py
index 4a2109edc8c91462b0a4062b6abd65e7fb506193..e3f53427d9a0cde5a3ff8a9496877644b7ca1dec 100644
--- a/addons/website_form/controllers/main.py
+++ b/addons/website_form/controllers/main.py
@@ -246,6 +246,7 @@ class WebsiteForm(http.Controller):
                     'no_auto_thread': False,
                     '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'),
                 }
                 mail_id = request.env['mail.message'].sudo().create(values)
         else: