diff --git a/mail_notification_custom_subject/README.rst b/mail_notification_custom_subject/README.rst
new file mode 100644
index 0000000000..aecd280f2e
--- /dev/null
+++ b/mail_notification_custom_subject/README.rst
@@ -0,0 +1,123 @@
+================================
+Mail Notification Custom Subject
+================================
+
+.. 
+   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+   !! This file is generated by oca-gen-addon-readme !!
+   !! changes will be overwritten.                   !!
+   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+   !! source digest: sha256:b873c6dfb9d094a1b5ebcd5c16a0c39a2127f4e7707aa54dd51dd4049f65d3fe
+   !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+.. |badge1| image:: https://img.shields.io/badge/maturity-Production%2FStable-green.png
+    :target: https://odoo-community.org/page/development-status
+    :alt: Production/Stable
+.. |badge2| image:: https://img.shields.io/badge/licence-AGPL--3-blue.png
+    :target: http://www.gnu.org/licenses/agpl-3.0-standalone.html
+    :alt: License: AGPL-3
+.. |badge3| image:: https://img.shields.io/badge/github-OCA%2Fsocial-lightgray.png?logo=github
+    :target: https://github.com/OCA/social/tree/16.0/mail_notification_custom_subject
+    :alt: OCA/social
+.. |badge4| image:: https://img.shields.io/badge/weblate-Translate%20me-F47D42.png
+    :target: https://translation.odoo-community.org/projects/social-16-0/social-16-0-mail_notification_custom_subject
+    :alt: Translate me on Weblate
+.. |badge5| image:: https://img.shields.io/badge/runboat-Try%20me-875A7B.png
+    :target: https://runboat.odoo-community.org/builds?repo=OCA/social&target_branch=16.0
+    :alt: Try me on Runboat
+
+|badge1| |badge2| |badge3| |badge4| |badge5|
+
+This module allows you to specify templates to override the subject on the notification
+emails sent by Odoo
+
+**Table of contents**
+
+.. contents::
+   :local:
+
+Configuration
+=============
+
+
+* Activate access to **Technical Features** (debug mode).
+* Go to **Settings > Technical > Email > Subject Replacement Templates**
+* Create a new template.
+
+    * The field **Model** specifies the model to which the subject template should apply in the notification emails sent by Odoo.
+    * The field **Subject Template** accepts `Jinja <https://jinja.palletsprojects.com/en/2.11.x/>`__ expressions.
+    * The field **Replace** specifies if the template should replace existing content or append to it.
+
+Usage
+=====
+
+To use this module, you need to:
+
+* Open the chatter in Odoo (e.g. Open an Invoice).
+* Send a message.
+* Observe the rendered Subject template.
+
+Bug Tracker
+===========
+
+Bugs are tracked on `GitHub Issues <https://github.com/OCA/social/issues>`_.
+In case of trouble, please check there if your issue has already been reported.
+If you spotted it first, help us to smash it by providing a detailed and welcomed
+`feedback <https://github.com/OCA/social/issues/new?body=module:%20mail_notification_custom_subject%0Aversion:%2016.0%0A%0A**Steps%20to%20reproduce**%0A-%20...%0A%0A**Current%20behavior**%0A%0A**Expected%20behavior**>`_.
+
+Do not contact contributors directly about support or help with technical issues.
+
+Credits
+=======
+
+Authors
+~~~~~~~
+
+* Tecnativa
+
+Contributors
+~~~~~~~~~~~~
+
+* Tecnativa <https://www.tecnativa.com>
+
+    * Pedro M. Baeza
+    * João Marques
+    * Carlos Roca
+    * Víctor Martínez
+
+* Versada <https://versada.eu>
+    * Naglis Jonaitis
+
+* Moduon <https://www.moduon.team>
+    * Eduardo de Miguel
+
+Maintainers
+~~~~~~~~~~~
+
+This module is maintained by the OCA.
+
+.. image:: https://odoo-community.org/logo.png
+   :alt: Odoo Community Association
+   :target: https://odoo-community.org
+
+OCA, or the Odoo Community Association, is a nonprofit organization whose
+mission is to support the collaborative development of Odoo features and
+promote its widespread use.
+
+.. |maintainer-yajo| image:: https://github.com/yajo.png?size=40px
+    :target: https://github.com/yajo
+    :alt: yajo
+.. |maintainer-edlopen| image:: https://github.com/edlopen.png?size=40px
+    :target: https://github.com/edlopen
+    :alt: edlopen
+.. |maintainer-rafaelbn| image:: https://github.com/rafaelbn.png?size=40px
+    :target: https://github.com/rafaelbn
+    :alt: rafaelbn
+
+Current `maintainers <https://odoo-community.org/page/maintainer-role>`__:
+
+|maintainer-yajo| |maintainer-edlopen| |maintainer-rafaelbn| 
+
+This module is part of the `OCA/social <https://github.com/OCA/social/tree/16.0/mail_notification_custom_subject>`_ project on GitHub.
+
+You are welcome to contribute. To learn how please visit https://odoo-community.org/page/Contribute.
diff --git a/mail_notification_custom_subject/__init__.py b/mail_notification_custom_subject/__init__.py
new file mode 100644
index 0000000000..0650744f6b
--- /dev/null
+++ b/mail_notification_custom_subject/__init__.py
@@ -0,0 +1 @@
+from . import models
diff --git a/mail_notification_custom_subject/__manifest__.py b/mail_notification_custom_subject/__manifest__.py
new file mode 100644
index 0000000000..71e2097ab5
--- /dev/null
+++ b/mail_notification_custom_subject/__manifest__.py
@@ -0,0 +1,21 @@
+# Copyright 2020-2021 Tecnativa - João Marques
+# Copyright 2021 Tecnativa - Pedro M. Baeza
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+{
+    "name": "Mail Notification Custom Subject",
+    "summary": "Apply a custom subject to mail notifications",
+    "version": "16.0.1.0.0",
+    "category": "Social Network",
+    "website": "https://github.com/OCA/social",
+    "author": "Tecnativa, Odoo Community Association (OCA)",
+    "license": "AGPL-3",
+    "installable": True,
+    "depends": ["mail"],
+    "data": [
+        "security/ir.model.access.csv",
+        "views/mail_notification_custom_subject_views.xml",
+    ],
+    "development_status": "Production/Stable",
+    "maintainers": ["yajo", "edlopen", "rafaelbn"],
+}
diff --git a/mail_notification_custom_subject/i18n/es.po b/mail_notification_custom_subject/i18n/es.po
new file mode 100644
index 0000000000..03ff0f0539
--- /dev/null
+++ b/mail_notification_custom_subject/i18n/es.po
@@ -0,0 +1,129 @@
+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* mail_notification_custom_subject
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 15.0\n"
+"Report-Msgid-Bugs-To: \n"
+"PO-Revision-Date: 2023-10-28 13:30+0000\n"
+"Last-Translator: Ivorra78 <informatica@totmaterial.es>\n"
+"Language-Team: none\n"
+"Language: es\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: \n"
+"Plural-Forms: nplurals=2; plural=n != 1;\n"
+"X-Generator: Weblate 4.17\n"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__append_after
+msgid "Append After"
+msgstr "Añadir Después"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__append_before
+msgid "Append Before"
+msgstr "Añadir antes de"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__subtype_ids
+msgid "Applied Subtypes"
+msgstr "Subtipos Aplicados"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__create_uid
+msgid "Created by"
+msgstr "Creado por"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__create_date
+msgid "Created on"
+msgstr "Creado el"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__display_name
+msgid "Display Name"
+msgstr "Mostrar Nombre"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model,name:mail_notification_custom_subject.model_mail_thread
+msgid "Email Thread"
+msgstr "Hilo de Correo Electrónico"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__id
+msgid "ID"
+msgstr "ID (identificación)"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject____last_update
+msgid "Last Modified on"
+msgstr "Última Modificación el"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__write_uid
+msgid "Last Updated by"
+msgstr "Actualizado por Última vez por"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__write_date
+msgid "Last Updated on"
+msgstr "Última Actualización el"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model,name:mail_notification_custom_subject.model_mail_message_custom_subject
+msgid "Mail Message Custom Subject"
+msgstr "Mensaje de correo Asunto personalizado"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__model_id
+msgid "Model"
+msgstr "Modelo"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__model_id
+msgid "Model where this template applies"
+msgstr "Modelo al que se aplica esta plantilla"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__position
+msgid "Position"
+msgstr "Posición"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__replace
+msgid "Replace"
+msgstr "Reemplazar"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__subject_template
+#: model_terms:ir.ui.view,arch_db:mail_notification_custom_subject.mail_notification_custom_subject_form
+msgid "Subject (placeholders may be used here)"
+msgstr "Asunto (pueden utilizarse marcadores de posición)"
+
+#. module: mail_notification_custom_subject
+#: model:ir.actions.act_window,name:mail_notification_custom_subject.action_mail_notification_custom_subject_tree_all
+#: model:ir.ui.menu,name:mail_notification_custom_subject.menu_mail_notification_custom_subject
+#: model_terms:ir.ui.view,arch_db:mail_notification_custom_subject.mail_notification_custom_subject_form
+msgid "Subject Replacement Templates"
+msgstr "Plantillas de Sustitución de Temas"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__subject_template
+msgid "Subject Template"
+msgstr "Tema Plantilla"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__name
+msgid "Template Name"
+msgstr "Nombre de Plantilla"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__position
+msgid ""
+"Whether to replace, append at beggining or append at end to other templates "
+"that apply to a given context"
+msgstr ""
+"Si reemplazar, añadir al principio o añadir al final a otras plantillas que "
+"se aplican a un contexto determinado"
diff --git a/mail_notification_custom_subject/i18n/es_ES.po b/mail_notification_custom_subject/i18n/es_ES.po
new file mode 100644
index 0000000000..680c521d33
--- /dev/null
+++ b/mail_notification_custom_subject/i18n/es_ES.po
@@ -0,0 +1,135 @@
+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* mail_notification_custom_subject
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 12.0\n"
+"Report-Msgid-Bugs-To: \n"
+"POT-Creation-Date: 2021-02-16 10:56+0000\n"
+"PO-Revision-Date: 2021-02-16 11:56+0100\n"
+"Last-Translator: Carlos <carlos.roca@tecnativa.com>\n"
+"Language-Team: \n"
+"Language: es_ES\n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: 8bit\n"
+"Plural-Forms: nplurals=2; plural=(n != 1);\n"
+"X-Generator: Poedit 2.0.6\n"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__append_after
+msgid "Append After"
+msgstr "Añadir después"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__append_before
+msgid "Append Before"
+msgstr "Añadir antes"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__subtype_ids
+msgid "Applied Subtypes"
+msgstr "Subtipos aplicados"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__create_uid
+msgid "Created by"
+msgstr "Creado por"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__create_date
+msgid "Created on"
+msgstr "Creado el"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__display_name
+msgid "Display Name"
+msgstr "Nombre mostrado"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model,name:mail_notification_custom_subject.model_mail_thread
+msgid "Email Thread"
+msgstr "Hilo de correo electrónico"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__id
+msgid "ID"
+msgstr "ID"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject____last_update
+msgid "Last Modified on"
+msgstr "Última modificación el"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__write_uid
+msgid "Last Updated by"
+msgstr "Última modificación por"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__write_date
+msgid "Last Updated on"
+msgstr "Última actualización el"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model,name:mail_notification_custom_subject.model_mail_message_custom_subject
+msgid "Mail Message Custom Subject"
+msgstr "Asunto Personalizado en Mensaje de Correo"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__model_id
+msgid "Model"
+msgstr "Modelo"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__model_id
+msgid "Model where this template applies"
+msgstr "Modelo en el que se aplica la plantilla"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__position
+msgid "Position"
+msgstr "Posición"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__replace
+msgid "Replace"
+msgstr "Sustituir"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__subject_template
+#: model_terms:ir.ui.view,arch_db:mail_notification_custom_subject.mail_notification_custom_subject_form
+msgid "Subject (placeholders may be used here)"
+msgstr "Asunto (se pueden utilizar aquí expresiones de campos)"
+
+#. module: mail_notification_custom_subject
+#: model:ir.actions.act_window,name:mail_notification_custom_subject.action_mail_notification_custom_subject_tree_all
+#: model:ir.ui.menu,name:mail_notification_custom_subject.menu_mail_notification_custom_subject
+#: model_terms:ir.ui.view,arch_db:mail_notification_custom_subject.mail_notification_custom_subject_form
+msgid "Subject Replacement Templates"
+msgstr "Plantillas de Sustitución de Asuntos"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__subject_template
+#, fuzzy
+msgid "Subject Template"
+msgstr "Plantillas de Sustitución de Asuntos"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__name
+#, fuzzy
+msgid "Template Name"
+msgstr "Plantillas"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__position
+msgid ""
+"Whether to replace, append at beggining or append at end to other templates "
+"that apply to a given context"
+msgstr ""
+"Ya sea para reemplazar, agregar al principio o agregar al final a otras "
+"plantillas que se aplican a un contexto determinado"
+
+#~ msgid "Templates"
+#~ msgstr "Plantillas"
diff --git a/mail_notification_custom_subject/i18n/mail_notification_custom_subject.pot b/mail_notification_custom_subject/i18n/mail_notification_custom_subject.pot
new file mode 100644
index 0000000000..50d826a7b5
--- /dev/null
+++ b/mail_notification_custom_subject/i18n/mail_notification_custom_subject.pot
@@ -0,0 +1,124 @@
+# Translation of Odoo Server.
+# This file contains the translation of the following modules:
+# 	* mail_notification_custom_subject
+#
+msgid ""
+msgstr ""
+"Project-Id-Version: Odoo Server 15.0\n"
+"Report-Msgid-Bugs-To: \n"
+"Last-Translator: \n"
+"Language-Team: \n"
+"MIME-Version: 1.0\n"
+"Content-Type: text/plain; charset=UTF-8\n"
+"Content-Transfer-Encoding: \n"
+"Plural-Forms: \n"
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__append_after
+msgid "Append After"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__append_before
+msgid "Append Before"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__subtype_ids
+msgid "Applied Subtypes"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__create_uid
+msgid "Created by"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__create_date
+msgid "Created on"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__display_name
+msgid "Display Name"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model,name:mail_notification_custom_subject.model_mail_thread
+msgid "Email Thread"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__id
+msgid "ID"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject____last_update
+msgid "Last Modified on"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__write_uid
+msgid "Last Updated by"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__write_date
+msgid "Last Updated on"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model,name:mail_notification_custom_subject.model_mail_message_custom_subject
+msgid "Mail Message Custom Subject"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__model_id
+msgid "Model"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__model_id
+msgid "Model where this template applies"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__position
+msgid "Position"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields.selection,name:mail_notification_custom_subject.selection__mail_message_custom_subject__position__replace
+msgid "Replace"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__subject_template
+#: model_terms:ir.ui.view,arch_db:mail_notification_custom_subject.mail_notification_custom_subject_form
+msgid "Subject (placeholders may be used here)"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.actions.act_window,name:mail_notification_custom_subject.action_mail_notification_custom_subject_tree_all
+#: model:ir.ui.menu,name:mail_notification_custom_subject.menu_mail_notification_custom_subject
+#: model_terms:ir.ui.view,arch_db:mail_notification_custom_subject.mail_notification_custom_subject_form
+msgid "Subject Replacement Templates"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__subject_template
+msgid "Subject Template"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,field_description:mail_notification_custom_subject.field_mail_message_custom_subject__name
+msgid "Template Name"
+msgstr ""
+
+#. module: mail_notification_custom_subject
+#: model:ir.model.fields,help:mail_notification_custom_subject.field_mail_message_custom_subject__position
+msgid ""
+"Whether to replace, append at beggining or append at end to other templates "
+"that apply to a given context"
+msgstr ""
diff --git a/mail_notification_custom_subject/models/__init__.py b/mail_notification_custom_subject/models/__init__.py
new file mode 100644
index 0000000000..3e5486eab2
--- /dev/null
+++ b/mail_notification_custom_subject/models/__init__.py
@@ -0,0 +1,2 @@
+from . import mail_thread
+from . import mail_message_custom_subject
diff --git a/mail_notification_custom_subject/models/mail_message_custom_subject.py b/mail_notification_custom_subject/models/mail_message_custom_subject.py
new file mode 100644
index 0000000000..4c8db6a8c2
--- /dev/null
+++ b/mail_notification_custom_subject/models/mail_message_custom_subject.py
@@ -0,0 +1,37 @@
+# Copyright 2020 Tecnativa - João Marques
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from odoo import fields, models
+
+
+class MailMessageCustomSubject(models.Model):
+    _name = "mail.message.custom.subject"
+    _description = "Mail Message Custom Subject"
+
+    name = fields.Char(string="Template Name")
+    model_id = fields.Many2one(
+        comodel_name="ir.model",
+        string="Model",
+        required=True,
+        help="Model where this template applies",
+        ondelete="cascade",
+    )
+    subtype_ids = fields.Many2many(
+        comodel_name="mail.message.subtype",
+        string="Applied Subtypes",
+        required=True,
+    )
+    subject_template = fields.Char(
+        required=True,
+        help="Subject (placeholders may be used here)",
+    )
+    position = fields.Selection(
+        selection=[
+            ("append_before", "Append Before"),
+            ("append_after", "Append After"),
+            ("replace", "Replace"),
+        ],
+        default="replace",
+        help="Whether to replace, append at beggining or append at end to other"
+        " templates that apply to a given context",
+    )
diff --git a/mail_notification_custom_subject/models/mail_thread.py b/mail_notification_custom_subject/models/mail_thread.py
new file mode 100644
index 0000000000..8b97a636c1
--- /dev/null
+++ b/mail_notification_custom_subject/models/mail_thread.py
@@ -0,0 +1,89 @@
+# Copyright 2020-2021 Tecnativa - João Marques
+# Copyright 2021 Tecnativa - Pedro M. Baeza
+# Copyright 2022 Moduon - Eduardo de Miguel
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from odoo import api, models
+
+
+class MailThread(models.AbstractModel):
+    _inherit = "mail.thread"
+
+    @api.returns("mail.message", lambda value: value.id)
+    def message_post(
+        self,
+        *,
+        body="",
+        subject=None,
+        message_type="notification",
+        email_from=None,
+        author_id=None,
+        parent_id=False,
+        subtype_xmlid=None,
+        subtype_id=False,
+        partner_ids=None,
+        attachments=None,
+        attachment_ids=None,
+        add_sign=True,
+        record_name=False,
+        **kwargs
+    ):
+        if subtype_xmlid:
+            subtype_id = self.env["ir.model.data"]._xmlid_to_res_id(
+                subtype_xmlid,
+                raise_if_not_found=False,
+            )
+        if not subtype_id:
+            subtype_id = self.env["ir.model.data"]._xmlid_to_res_id("mail.mt_note")
+        if subtype_id:
+            custom_subjects = (
+                self.env["mail.message.custom.subject"]
+                .sudo()
+                .search(
+                    [
+                        ("model_id.model", "=", self._name),
+                        ("subtype_ids", "=", subtype_id),
+                    ]
+                )
+                .sudo(False)
+            )
+            if not subject:
+                subject = "Re: %s" % self.env["mail.message"].with_context(
+                    default_model=self._name,
+                    default_res_id=self.id,
+                )._get_record_name({})
+            for template in custom_subjects:
+                try:
+                    rendered_subject_template = self.env[
+                        "mail.template"
+                    ]._render_template(
+                        template_src=template.subject_template,
+                        model=self._name,
+                        res_ids=[self.id],
+                    )[
+                        self.id
+                    ]
+                    if template.position == "replace":
+                        subject = rendered_subject_template
+                    elif template.position == "append_before":
+                        subject = rendered_subject_template + subject
+                    elif template.position == "append_after":
+                        subject += rendered_subject_template
+                except Exception:
+                    rendered_subject_template = False
+        return super().message_post(
+            body=body,
+            subject=subject,
+            message_type=message_type,
+            email_from=email_from,
+            author_id=author_id,
+            parent_id=parent_id,
+            subtype_xmlid=subtype_xmlid,
+            subtype_id=subtype_id,
+            partner_ids=partner_ids,
+            attachments=attachments,
+            attachment_ids=attachment_ids,
+            add_sign=add_sign,
+            record_name=record_name,
+            **kwargs,
+        )
diff --git a/mail_notification_custom_subject/readme/CONFIGURE.rst b/mail_notification_custom_subject/readme/CONFIGURE.rst
new file mode 100644
index 0000000000..c777ed3ae9
--- /dev/null
+++ b/mail_notification_custom_subject/readme/CONFIGURE.rst
@@ -0,0 +1,8 @@
+
+* Activate access to **Technical Features** (debug mode).
+* Go to **Settings > Technical > Email > Subject Replacement Templates**
+* Create a new template.
+
+    * The field **Model** specifies the model to which the subject template should apply in the notification emails sent by Odoo.
+    * The field **Subject Template** accepts `Jinja <https://jinja.palletsprojects.com/en/2.11.x/>`__ expressions.
+    * The field **Replace** specifies if the template should replace existing content or append to it.
diff --git a/mail_notification_custom_subject/readme/CONTRIBUTORS.rst b/mail_notification_custom_subject/readme/CONTRIBUTORS.rst
new file mode 100644
index 0000000000..f88a42efed
--- /dev/null
+++ b/mail_notification_custom_subject/readme/CONTRIBUTORS.rst
@@ -0,0 +1,12 @@
+* Tecnativa <https://www.tecnativa.com>
+
+    * Pedro M. Baeza
+    * João Marques
+    * Carlos Roca
+    * Víctor Martínez
+
+* Versada <https://versada.eu>
+    * Naglis Jonaitis
+
+* Moduon <https://www.moduon.team>
+    * Eduardo de Miguel
diff --git a/mail_notification_custom_subject/readme/DESCRIPTION.rst b/mail_notification_custom_subject/readme/DESCRIPTION.rst
new file mode 100644
index 0000000000..2b0727f1ad
--- /dev/null
+++ b/mail_notification_custom_subject/readme/DESCRIPTION.rst
@@ -0,0 +1,2 @@
+This module allows you to specify templates to override the subject on the notification
+emails sent by Odoo
diff --git a/mail_notification_custom_subject/readme/USAGE.rst b/mail_notification_custom_subject/readme/USAGE.rst
new file mode 100644
index 0000000000..49bed60a72
--- /dev/null
+++ b/mail_notification_custom_subject/readme/USAGE.rst
@@ -0,0 +1,5 @@
+To use this module, you need to:
+
+* Open the chatter in Odoo (e.g. Open an Invoice).
+* Send a message.
+* Observe the rendered Subject template.
diff --git a/mail_notification_custom_subject/security/ir.model.access.csv b/mail_notification_custom_subject/security/ir.model.access.csv
new file mode 100644
index 0000000000..bc15034ae6
--- /dev/null
+++ b/mail_notification_custom_subject/security/ir.model.access.csv
@@ -0,0 +1,3 @@
+id,name,model_id:id,group_id:id,perm_read,perm_write,perm_create,perm_unlink
+access_mail_notification_custom_subject_user,mail_notification_custom_object,model_mail_message_custom_subject,base.group_user,1,0,0,0
+access_mail_notification_custom_subject_admin,mail_notification_custom_object,model_mail_message_custom_subject,base.group_system,1,1,1,1
diff --git a/mail_notification_custom_subject/static/description/icon.png b/mail_notification_custom_subject/static/description/icon.png
new file mode 100644
index 0000000000..3a0328b516
Binary files /dev/null and b/mail_notification_custom_subject/static/description/icon.png differ
diff --git a/mail_notification_custom_subject/static/description/index.html b/mail_notification_custom_subject/static/description/index.html
new file mode 100644
index 0000000000..7afebcf789
--- /dev/null
+++ b/mail_notification_custom_subject/static/description/index.html
@@ -0,0 +1,477 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+<meta name="generator" content="Docutils: https://docutils.sourceforge.io/" />
+<title>Mail Notification Custom Subject</title>
+<style type="text/css">
+
+/*
+:Author: David Goodger (goodger@python.org)
+:Id: $Id: html4css1.css 8954 2022-01-20 10:10:25Z milde $
+:Copyright: This stylesheet has been placed in the public domain.
+
+Default cascading style sheet for the HTML output of Docutils.
+
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+</style>
+</head>
+<body>
+<div class="document" id="mail-notification-custom-subject">
+<h1 class="title">Mail Notification Custom Subject</h1>
+
+<!-- !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+!! This file is generated by oca-gen-addon-readme !!
+!! changes will be overwritten.                   !!
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+!! source digest: sha256:b873c6dfb9d094a1b5ebcd5c16a0c39a2127f4e7707aa54dd51dd4049f65d3fe
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! -->
+<p><a class="reference external image-reference" href="https://odoo-community.org/page/development-status"><img alt="Production/Stable" src="https://img.shields.io/badge/maturity-Production%2FStable-green.png" /></a> <a class="reference external image-reference" href="http://www.gnu.org/licenses/agpl-3.0-standalone.html"><img alt="License: AGPL-3" src="https://img.shields.io/badge/licence-AGPL--3-blue.png" /></a> <a class="reference external image-reference" href="https://github.com/OCA/social/tree/16.0/mail_notification_custom_subject"><img alt="OCA/social" src="https://img.shields.io/badge/github-OCA%2Fsocial-lightgray.png?logo=github" /></a> <a class="reference external image-reference" href="https://translation.odoo-community.org/projects/social-16-0/social-16-0-mail_notification_custom_subject"><img alt="Translate me on Weblate" src="https://img.shields.io/badge/weblate-Translate%20me-F47D42.png" /></a> <a class="reference external image-reference" href="https://runboat.odoo-community.org/builds?repo=OCA/social&amp;target_branch=16.0"><img alt="Try me on Runboat" src="https://img.shields.io/badge/runboat-Try%20me-875A7B.png" /></a></p>
+<p>This module allows you to specify templates to override the subject on the notification
+emails sent by Odoo</p>
+<p><strong>Table of contents</strong></p>
+<div class="contents local topic" id="contents">
+<ul class="simple">
+<li><a class="reference internal" href="#configuration" id="toc-entry-1">Configuration</a></li>
+<li><a class="reference internal" href="#usage" id="toc-entry-2">Usage</a></li>
+<li><a class="reference internal" href="#bug-tracker" id="toc-entry-3">Bug Tracker</a></li>
+<li><a class="reference internal" href="#credits" id="toc-entry-4">Credits</a><ul>
+<li><a class="reference internal" href="#authors" id="toc-entry-5">Authors</a></li>
+<li><a class="reference internal" href="#contributors" id="toc-entry-6">Contributors</a></li>
+<li><a class="reference internal" href="#maintainers" id="toc-entry-7">Maintainers</a></li>
+</ul>
+</li>
+</ul>
+</div>
+<div class="section" id="configuration">
+<h1><a class="toc-backref" href="#toc-entry-1">Configuration</a></h1>
+<ul>
+<li><p class="first">Activate access to <strong>Technical Features</strong> (debug mode).</p>
+</li>
+<li><p class="first">Go to <strong>Settings &gt; Technical &gt; Email &gt; Subject Replacement Templates</strong></p>
+</li>
+<li><p class="first">Create a new template.</p>
+<blockquote>
+<ul class="simple">
+<li>The field <strong>Model</strong> specifies the model to which the subject template should apply in the notification emails sent by Odoo.</li>
+<li>The field <strong>Subject Template</strong> accepts <a class="reference external" href="https://jinja.palletsprojects.com/en/2.11.x/">Jinja</a> expressions.</li>
+<li>The field <strong>Replace</strong> specifies if the template should replace existing content or append to it.</li>
+</ul>
+</blockquote>
+</li>
+</ul>
+</div>
+<div class="section" id="usage">
+<h1><a class="toc-backref" href="#toc-entry-2">Usage</a></h1>
+<p>To use this module, you need to:</p>
+<ul class="simple">
+<li>Open the chatter in Odoo (e.g. Open an Invoice).</li>
+<li>Send a message.</li>
+<li>Observe the rendered Subject template.</li>
+</ul>
+</div>
+<div class="section" id="bug-tracker">
+<h1><a class="toc-backref" href="#toc-entry-3">Bug Tracker</a></h1>
+<p>Bugs are tracked on <a class="reference external" href="https://github.com/OCA/social/issues">GitHub Issues</a>.
+In case of trouble, please check there if your issue has already been reported.
+If you spotted it first, help us to smash it by providing a detailed and welcomed
+<a class="reference external" href="https://github.com/OCA/social/issues/new?body=module:%20mail_notification_custom_subject%0Aversion:%2016.0%0A%0A**Steps%20to%20reproduce**%0A-%20...%0A%0A**Current%20behavior**%0A%0A**Expected%20behavior**">feedback</a>.</p>
+<p>Do not contact contributors directly about support or help with technical issues.</p>
+</div>
+<div class="section" id="credits">
+<h1><a class="toc-backref" href="#toc-entry-4">Credits</a></h1>
+<div class="section" id="authors">
+<h2><a class="toc-backref" href="#toc-entry-5">Authors</a></h2>
+<ul class="simple">
+<li>Tecnativa</li>
+</ul>
+</div>
+<div class="section" id="contributors">
+<h2><a class="toc-backref" href="#toc-entry-6">Contributors</a></h2>
+<ul>
+<li><p class="first">Tecnativa &lt;<a class="reference external" href="https://www.tecnativa.com">https://www.tecnativa.com</a>&gt;</p>
+<blockquote>
+<ul class="simple">
+<li>Pedro M. Baeza</li>
+<li>João Marques</li>
+<li>Carlos Roca</li>
+<li>Víctor Martínez</li>
+</ul>
+</blockquote>
+</li>
+<li><dl class="first docutils">
+<dt>Versada &lt;<a class="reference external" href="https://versada.eu">https://versada.eu</a>&gt;</dt>
+<dd><ul class="first last simple">
+<li>Naglis Jonaitis</li>
+</ul>
+</dd>
+</dl>
+</li>
+<li><dl class="first docutils">
+<dt>Moduon &lt;<a class="reference external" href="https://www.moduon.team">https://www.moduon.team</a>&gt;</dt>
+<dd><ul class="first last simple">
+<li>Eduardo de Miguel</li>
+</ul>
+</dd>
+</dl>
+</li>
+</ul>
+</div>
+<div class="section" id="maintainers">
+<h2><a class="toc-backref" href="#toc-entry-7">Maintainers</a></h2>
+<p>This module is maintained by the OCA.</p>
+<a class="reference external image-reference" href="https://odoo-community.org"><img alt="Odoo Community Association" src="https://odoo-community.org/logo.png" /></a>
+<p>OCA, or the Odoo Community Association, is a nonprofit organization whose
+mission is to support the collaborative development of Odoo features and
+promote its widespread use.</p>
+<p>Current <a class="reference external" href="https://odoo-community.org/page/maintainer-role">maintainers</a>:</p>
+<p><a class="reference external image-reference" href="https://github.com/yajo"><img alt="yajo" src="https://github.com/yajo.png?size=40px" /></a> <a class="reference external image-reference" href="https://github.com/edlopen"><img alt="edlopen" src="https://github.com/edlopen.png?size=40px" /></a> <a class="reference external image-reference" href="https://github.com/rafaelbn"><img alt="rafaelbn" src="https://github.com/rafaelbn.png?size=40px" /></a></p>
+<p>This module is part of the <a class="reference external" href="https://github.com/OCA/social/tree/16.0/mail_notification_custom_subject">OCA/social</a> project on GitHub.</p>
+<p>You are welcome to contribute. To learn how please visit <a class="reference external" href="https://odoo-community.org/page/Contribute">https://odoo-community.org/page/Contribute</a>.</p>
+</div>
+</div>
+</div>
+</body>
+</html>
diff --git a/mail_notification_custom_subject/tests/__init__.py b/mail_notification_custom_subject/tests/__init__.py
new file mode 100644
index 0000000000..b0f2b2eff5
--- /dev/null
+++ b/mail_notification_custom_subject/tests/__init__.py
@@ -0,0 +1 @@
+from . import test_mail_notification_custom_subject
diff --git a/mail_notification_custom_subject/tests/test_mail_notification_custom_subject.py b/mail_notification_custom_subject/tests/test_mail_notification_custom_subject.py
new file mode 100644
index 0000000000..078e19d5a9
--- /dev/null
+++ b/mail_notification_custom_subject/tests/test_mail_notification_custom_subject.py
@@ -0,0 +1,193 @@
+# Copyright 2020 Tecnativa - João Marques
+# Copyright 2022 Tecnativa - Víctor Martínez
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+# pylint: disable=C8107
+from odoo.tests import common
+from odoo.tools import mute_logger
+
+
+class TestMailNotificationCustomSubject(common.TransactionCase):
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.partner_1, cls.partner_2 = (
+            cls.env["res.partner"]
+            .with_context(tracking_disable=True)
+            .create(
+                [
+                    {"name": "Test partner 1", "email": "partner1@example.com"},
+                    {"name": "Test partner 2", "email": "partner2@example.com"},
+                ]
+            )
+        )
+        cls.admin = common.new_test_user(cls.env, "boss", "base.group_system")
+
+    def setUp(self):
+        super().setUp()
+        self.uid = common.new_test_user(self.env, "worker")
+
+    def test_email_subject_template_overrides(self):
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test template 1",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{object.name or 'n/a'}} and something more",
+                }
+            )
+        # Send message in partner
+        mail_message_1 = self.partner_1.message_post(
+            body="Test", subtype_xmlid="mail.mt_comment"
+        )
+        # Get message and check subject
+        self.assertEqual(mail_message_1.subject, "Test partner 1 and something more")
+
+        # Send message in partner 2
+        mail_message_2 = self.partner_2.message_post(
+            body="Test", subtype_xmlid="mail.mt_comment"
+        )
+        # Get message and check subject
+        self.assertEqual(mail_message_2.subject, "Test partner 2 and something more")
+
+        # Explicit subject should also be overwritten
+        mail_message_3 = self.partner_2.message_post(
+            body="Test", subtype_xmlid="mail.mt_comment", subject="Test"
+        )
+        # Get message and check subject
+        self.assertEqual(mail_message_3.subject, "Test partner 2 and something more")
+
+    def test_email_subject_template_normal(self):
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test template 1",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{object.name or 'n/a'}} and something more",
+                }
+            )
+        # Send note in partner
+        mail_message_1 = self.partner_1.message_post(
+            body="Test", subtype_xmlid="mail.mt_note", subject="Test"
+        )
+        # Get message and check subject. Subject Template should not apply
+        self.assertEqual(mail_message_1.subject, "Test")
+
+    def test_email_subject_template_multi(self):
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test template 1",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{object.name or 'n/a'}} and something more",
+                }
+            )
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test template 2",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{object.name or 'n/a'}} and something different",
+                }
+            )
+        # Send message in partner
+        mail_message_1 = self.partner_1.message_post(
+            body="Test", subtype_xmlid="mail.mt_comment"
+        )
+        # Get message and check subject
+        self.assertEqual(
+            mail_message_1.subject, "Test partner 1 and something different"
+        )
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test template 3",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{' and yet something else'}}",
+                    "position": "append_after",
+                }
+            )
+        # Send message in partner
+        mail_message_2 = self.partner_1.message_post(
+            body="Test", subtype_xmlid="mail.mt_comment"
+        )
+        # Get message and check subject
+        self.assertEqual(
+            mail_message_2.subject,
+            "Test partner 1 and something different and yet something else",
+        )
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test template 4",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{'Re: '}}",
+                    "position": "append_before",
+                }
+            )
+        # Send message in partner
+        mail_message_3 = self.partner_1.message_post(
+            body="Test", subtype_xmlid="mail.mt_comment"
+        )
+        # Get message and check subject
+        self.assertEqual(
+            mail_message_3.subject,
+            "Re: Test partner 1 and something different and yet something else",
+        )
+
+    def test_email_subject_template_w_original(self):
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test template 1",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{' and something more'}}",
+                    "position": "append_after",
+                }
+            )
+        # Send message in partner
+        mail_message_1 = self.partner_1.message_post(
+            body="Test",
+            subtype_xmlid="mail.mt_comment",
+            subject="Test",
+        )
+        # Get message and check subject
+        self.assertEqual(mail_message_1.subject, "Test and something more")
+
+    def test_bad_template_does_not_break(self):
+        """Create template with error (obaject) to test error."""
+        with self.with_user("boss"):
+            self.env["mail.message.custom.subject"].create(
+                {
+                    "name": "Test bad template 1",
+                    "model_id": self.env.ref("base.model_res_partner").id,
+                    "subtype_ids": [(6, 0, [self.env.ref("mail.mt_comment").id])],
+                    "subject_template": "{{obaject.number_a}} and something",
+                    "position": "append_after",
+                }
+            )
+        # Send message in partner
+        with mute_logger("odoo.addons.mail.models.mail_render_mixin"):
+            mail_message_1 = self.partner_1.message_post(
+                body="Test",
+                subtype_xmlid="mail.mt_comment",
+                subject="Test",
+            )
+        # Get message and check subject
+        # No exception should be raised but subject should remain as original.
+        self.assertEqual(mail_message_1.subject, "Test")
+
+    def test_no_template_default_result(self):
+        # Send message in partner
+        mail_message_1 = self.partner_1.message_post(
+            body="Test", subtype_xmlid="mail.mt_comment", subject="Test partner 1"
+        )
+        # Get message and check subject
+        # No exception should be raised but subject should remain as original.
+        self.assertEqual(mail_message_1.subject, "Test partner 1")
diff --git a/mail_notification_custom_subject/views/mail_notification_custom_subject_views.xml b/mail_notification_custom_subject/views/mail_notification_custom_subject_views.xml
new file mode 100644
index 0000000000..3267af9fbb
--- /dev/null
+++ b/mail_notification_custom_subject/views/mail_notification_custom_subject_views.xml
@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<odoo>
+    <record model="ir.ui.view" id="mail_notification_custom_subject_form">
+        <field name="name">mail.message.custom.subject.form</field>
+        <field name="model">mail.message.custom.subject</field>
+        <field name="arch" type="xml">
+            <form string="Subject Replacement Templates">
+                <sheet>
+                    <div class="oe_title">
+                        <label for="name" class="oe_edit_only" />
+                        <h1 name="name"><field name="name" /></h1>
+                    </div>
+                    <group>
+                        <field
+                            name="subject_template"
+                            placeholder="Subject (placeholders may be used here)"
+                        />
+                        <field name="model_id" options="{'no_create': True}" />
+                        <field name="subtype_ids" widget="many2many_tags" />
+                        <field name="position" />
+                    </group>
+                </sheet>
+            </form>
+        </field>
+    </record>
+    <record model="ir.ui.view" id="mail_notification_custom_subject_tree">
+        <field name="name">mail.message.custom.subject.tree</field>
+        <field name="model">mail.message.custom.subject</field>
+        <field name="arch" type="xml">
+            <tree>
+                <field name="name" />
+                <field name="model_id" />
+                <field name="subtype_ids" />
+                <field name="subject_template" />
+            </tree>
+        </field>
+    </record>
+    <record
+        model="ir.actions.act_window"
+        id="action_mail_notification_custom_subject_tree_all"
+    >
+        <field name="name">Subject Replacement Templates</field>
+        <field name="res_model">mail.message.custom.subject</field>
+        <field name="view_mode">form,tree</field>
+        <field name="view_id" ref="mail_notification_custom_subject_tree" />
+    </record>
+    <menuitem
+        id="menu_mail_notification_custom_subject"
+        parent="base.menu_email"
+        action="action_mail_notification_custom_subject_tree_all"
+        sequence="21"
+    />
+</odoo>
diff --git a/setup/mail_notification_custom_subject/odoo/addons/mail_notification_custom_subject b/setup/mail_notification_custom_subject/odoo/addons/mail_notification_custom_subject
new file mode 120000
index 0000000000..5212ccad70
--- /dev/null
+++ b/setup/mail_notification_custom_subject/odoo/addons/mail_notification_custom_subject
@@ -0,0 +1 @@
+../../../../mail_notification_custom_subject
\ No newline at end of file
diff --git a/setup/mail_notification_custom_subject/setup.py b/setup/mail_notification_custom_subject/setup.py
new file mode 100644
index 0000000000..28c57bb640
--- /dev/null
+++ b/setup/mail_notification_custom_subject/setup.py
@@ -0,0 +1,6 @@
+import setuptools
+
+setuptools.setup(
+    setup_requires=['setuptools-odoo'],
+    odoo_addon=True,
+)