diff --git a/addons/account/models/account_move.py b/addons/account/models/account_move.py
index 377a85b191c..0f87d565aae 100644
--- a/addons/account/models/account_move.py
+++ b/addons/account/models/account_move.py
@@ -3584,13 +3584,15 @@ class AccountMove(models.Model):
             message, msg_vals, model_description=model_description,
             force_email_company=force_email_company, force_email_lang=force_email_lang
         )
+        subtitles = [render_context['record'].name]
         if self.invoice_date_due:
-            render_context['subtitle'] = _('%(amount)s due\N{NO-BREAK SPACE}%(date)s',
+            subtitles.append(_('%(amount)s due\N{NO-BREAK SPACE}%(date)s',
                            amount=format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')),
                            date=format_date(self.env, self.invoice_date_due, date_format='short', lang_code=render_context.get('lang'))
-                          )
+                          ))
         else:
-            render_context['subtitle'] = format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang'))
+            subtitles.append(format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')))
+        render_context['subtitles'] = subtitles
         return render_context
 
     # -------------------------------------------------------------------------
diff --git a/addons/crm/models/crm_lead.py b/addons/crm/models/crm_lead.py
index 2586bceff1e..db4613877ab 100644
--- a/addons/crm/models/crm_lead.py
+++ b/addons/crm/models/crm_lead.py
@@ -16,6 +16,7 @@ from odoo.exceptions import UserError, AccessError
 from odoo.osv import expression
 from odoo.tools.translate import _
 from odoo.tools import date_utils, email_re, email_split, is_html_empty, groupby
+from odoo.tools.misc import get_lang
 
 from . import crm_stage
 
@@ -1792,6 +1793,17 @@ class Lead(models.Model):
             return self.env.ref('crm.mt_lead_lost')
         return super(Lead, self)._track_subtype(init_values)
 
+    def _notify_by_email_prepare_rendering_context(self, message, msg_vals=False, model_description=False,
+                                                   force_email_company=False, force_email_lang=False):
+        render_context = super()._notify_by_email_prepare_rendering_context(
+            message, msg_vals, model_description=model_description,
+            force_email_company=force_email_company, force_email_lang=force_email_lang
+        )
+        if self.date_deadline:
+            render_context['subtitles'].append(
+                _('Deadline: %s', self.date_deadline.strftime(get_lang(self.env).date_format)))
+        return render_context
+
     def _notify_get_recipients_groups(self, msg_vals=None):
         """ Handle salesman recipients that can convert leads into opportunities
         and set opportunities as won / lost. """
diff --git a/addons/mail/data/mail_templates_chatter.xml b/addons/mail/data/mail_templates_chatter.xml
index 3d86bdfe9ec..a230a48b603 100644
--- a/addons/mail/data/mail_templates_chatter.xml
+++ b/addons/mail/data/mail_templates_chatter.xml
@@ -3,15 +3,12 @@
     <data>
         <!-- Discuss utility templates for notifications -->
         <template id="message_user_assigned">
-<p style="margin: 0px;">
-    <span>Dear <t t-esc="object.user_id.sudo().name"/>,</span><br />
+<div style="margin: 0px; padding: 0px; font-size: 13px;">
+    <span>Dear <t t-esc="object.user_id.sudo().name"/>,</span>
+    <br/><br/>
     <span style="margin-top: 8px;">You have been assigned to the <t t-esc="model_description or 'document'"/> <t t-esc="object.display_name"/>.</span>
-</p>
-<p style="padding-top: 24px; padding-bottom: 16px;">
-    <a t-att-href="access_link" t-att-data-oe-model="object._name" t-att-data-oe-id="object.id" style="background-color:#875A7B; padding: 10px; text-decoration: none; color: #fff; border-radius: 5px;">
-            View <t t-esc="model_description or 'document'"/>
-    </a>
-</p>
+    <br/>
+</div>
         </template>
 
         <template id="message_activity_done">
@@ -36,17 +33,18 @@
 
         <template id="message_activity_assigned">
 <div style="margin: 0px; padding: 0px; font-size: 13px;">
-    <span t-field="activity.create_uid.name"/> assigned you an activity <span t-field="activity.activity_type_id.name"/>
-    <t t-if="activity.summary">(<span t-field="activity.summary"/>)</t>
-    on <span t-field="activity.res_name"/>
-    to close for <span t-field="activity.date_deadline"/>.<br />
-    <p style="padding: 16px 0px 16px 0px;">
-        <a t-att-href="access_link" t-att-data-oe-model="activity.res_model" t-att-data-oe-id="activity.res_id"
-            style="background-color:#875A7B; padding: 8px 16px 8px 16px; text-decoration: none; color: #fff; border-radius: 5px;">
-            View <t t-esc="model_description or 'document'"/>
-        </a>
+    Dear <span t-field="activity.user_id.name"/>,
+    <br/><br/>
+    <p>
+        <span t-field="activity.create_uid.name"/> has just assigned you the following activity:
+        <ul>
+            <li>Document: "<t t-esc="activity.res_name"/>"
+                <t t-if="model_description"> (<t t-esc="model_description"/>)</t>
+            </li>
+            <li t-if="activity.summary">Summary: <span t-field="activity.summary"/></li>
+            <li>Deadline: <span t-field="activity.date_deadline"/></li>
+        </ul>
     </p>
-    <div t-if="activity.note" style="margin-top: 8px;" t-field="activity.note"/>
 </div>
         </template>
 
diff --git a/addons/mail/data/mail_templates_email_layouts.xml b/addons/mail/data/mail_templates_email_layouts.xml
index 9ec93330306..859ab2c84e7 100644
--- a/addons/mail/data/mail_templates_email_layouts.xml
+++ b/addons/mail/data/mail_templates_email_layouts.xml
@@ -168,8 +168,7 @@
 </html>
         </template>
 
-        <!-- Used mainly in conjunction of portal models (SO, PO, Invoices) although not mandatory -->
-        <template id="mail_notification_paynow" name="Mail: Pay Now mail notification template">
+        <template id="mail_notification_layout" name="Mail: mail notification layout template">
 <html t-att-lang="lang">
 <header>
     <meta http-equiv="Content-Type" content="text/html charset=UTF-8" />
@@ -201,17 +200,27 @@
                             </td></tr>
                         </table></td><td width="7"></td><!--only inner cellspacing-->
                     </t>
-                    <t t-if="not has_button_access and is_html_empty(subtitle)">
+                    <t t-if="not has_button_access and not subtitles">
                         <td>
                             <span style="font-size: 10px;">Your <t t-out="model_description or 'document'"/></span>
                             <br />
-                            <span style="font-size: 20px; font-weight: bold;">
+                            <span style="font-size: 12px; font-weight: bold;">
                                 <t t-out="message.record_name and message.record_name.replace('/','-') or ''"/>
                             </span>
                         </td><td width="7"></td>
                     </t>
+                    <t t-if="subtitles">
+                        <td style="font-size: 12px;">
+                            <t t-foreach="subtitles" t-as="subtitle">
+                                <span t-attf-style="{{ 'font-weight:bold;' if subtitle_first else '' }}"
+                                      t-out="subtitle"/>
+                                <br t-if="not subtitle_last"/>
+                            </t>
+                        </td>
+                    </t>
                     <t t-if="actions">
-                        <td>
+                        <td>&amp;nbsp;</td>
+                        <td style="font-size: 12px;">
                             <t t-foreach="actions" t-as="action">
                                 |
                                 <a t-att-href="action['url']" style="color: #875A7B; text-decoration:none !important; text-decoration: none;">
@@ -220,12 +229,6 @@
                             </t>
                         </td><td width="7"></td>
                     </t>
-                    <t t-if="not is_html_empty(subtitle)">
-                        <td style="font-size: 12px;">
-                            <span style="font-weight:bold;" t-out="record.name"/><br/>
-                            <span t-out="subtitle"/>
-                        </td>
-                    </t>
                 </tr></table></td></tr>
                 <tr><td>
                     <hr width="100%" style="background-color:rgb(204,204,204);border:medium none;clear:both;display:block;font-size:0px;min-height:1px;line-height:0; margin: 5px 0px;"/>
@@ -237,13 +240,10 @@
     <tr>
         <td style="padding-left: 5px;">
             <t t-out="message.body"/>
-            <t t-if="email_add_signature and 'user_id' in record and record.user_id and not record.env.user._is_superuser() and not is_html_empty(record.user_id.sudo().signature)">
-                <div style="margin: 0px; padding: 0px; font-size:13px;">
-                    Best regards,
-                </div>
-                <div>&amp;nbsp;</div>
+            <t t-if="email_add_signature and not is_html_empty(signature)" class="o_signature">
+                <br/>
                 <div style="font-size: 13px;">
-                    <div t-out="record.user_id.sudo().signature"/>
+                    <div t-out="signature"/>
                 </div>
             </t>
         </td>
@@ -286,5 +286,17 @@
     <t t-out="'&#847; &#8203; ' * 140"/>
 </div>
         </template>
+
+        <template id="mail_notification_paynow" name="Mail: Pay Now mail notification template"
+                  inherit_id="mail.mail_notification_layout" primary="True">
+            <xpath expr="//t[hasclass('o_signature')]" position="replace">
+                <t t-if="email_add_signature and 'user_id' in record and record.user_id and not record.env.user._is_superuser() and not is_html_empty(record.user_id.sudo().signature)">
+                    <br/>
+                    <div style="font-size: 13px;">
+                        <div t-out="record.user_id.sudo().signature"/>
+                    </div>
+                </t>
+            </xpath>
+        </template>
     </data>
 </odoo>
diff --git a/addons/mail/models/mail_activity.py b/addons/mail/models/mail_activity.py
index 2ce53932299..fd4d3a925e8 100644
--- a/addons/mail/models/mail_activity.py
+++ b/addons/mail/models/mail_activity.py
@@ -9,7 +9,8 @@ from dateutil.relativedelta import relativedelta
 
 from odoo import api, exceptions, fields, models, _, Command
 from odoo.osv import expression
-from odoo.tools.misc import clean_context
+from odoo.tools import is_html_empty
+from odoo.tools.misc import clean_context, get_lang
 
 
 class MailActivity(models.Model):
@@ -480,11 +481,11 @@ class MailActivity(models.Model):
             model_description = activity.env['ir.model']._get(activity.res_model).display_name
             body = activity.env['ir.qweb']._render(
                 'mail.message_activity_assigned',
-                dict(
-                    activity=activity,
-                    model_description=model_description,
-                    access_link=activity.env['mail.thread']._notify_get_action_link('view', model=activity.res_model, res_id=activity.res_id),
-                ),
+                {
+                    'activity': activity,
+                    'model_description': model_description,
+                    'is_html_empty': is_html_empty,
+                },
                 minimal_qcontext=True
             )
             record = activity.env[activity.res_model].browse(activity.res_id)
@@ -492,12 +493,14 @@ class MailActivity(models.Model):
                 record.message_notify(
                     partner_ids=activity.user_id.partner_id.ids,
                     body=body,
-                    subject=_('%(activity_name)s: %(summary)s assigned to you',
-                        activity_name=activity.res_name,
-                        summary=activity.summary or activity.activity_type_id.name),
                     record_name=activity.res_name,
                     model_description=model_description,
-                    email_layout_xmlid='mail.mail_notification_light',
+                    email_layout_xmlid='mail.mail_notification_layout',
+                    subject=_('"%(activity_name)s: %(summary)s" assigned to you',
+                              activity_name=activity.res_name,
+                              summary=activity.summary or activity.activity_type_id.name),
+                    subtitles=[_('Activity: %s', activity.activity_type_id.name),
+                               _('Deadline: %s', activity.date_deadline.strftime(get_lang(activity.env).date_format))]
                 )
 
     def action_done(self):
diff --git a/addons/mail/models/mail_thread.py b/addons/mail/models/mail_thread.py
index a0e84dfacb1..bcb32901d4a 100644
--- a/addons/mail/models/mail_thread.py
+++ b/addons/mail/models/mail_thread.py
@@ -2411,7 +2411,7 @@ class MailThread(models.AbstractModel):
                                 mail_auto_delete=True,  # mail.mail
                                 model_description=False, force_email_company=False, force_email_lang=False,  # rendering
                                 resend_existing=False, force_send=True, send_after_commit=True,  # email send
-                                **kwargs):
+                                subtitles=None, **kwargs):
         """ Method to send email linked to notified messages.
 
         :param message: ``mail.message`` record to notify;
@@ -2442,6 +2442,7 @@ class MailThread(models.AbstractModel):
         :param force_send: send emails directly instead of using queue;
         :param send_after_commit: if force_send, tells whether to send emails after
           the transaction has been committed using a post-commit hook;
+        :param subtitles: optional list that will be set as template value "subtitles"
         """
         partners_data = [r for r in recipients_data if r['notif'] == 'email']
         if not partners_data:
@@ -2460,6 +2461,8 @@ class MailThread(models.AbstractModel):
             force_email_company=force_email_company,
             force_email_lang=force_email_lang,
         ) # 10 queries
+        if subtitles:
+            template_values['subtitles'] = subtitles
 
         email_layout_xmlid = msg_vals.get('email_layout_xmlid') if msg_vals else message.email_layout_xmlid
         template_xmlid = email_layout_xmlid if email_layout_xmlid else 'mail.message_notification_email'
@@ -2649,7 +2652,7 @@ class MailThread(models.AbstractModel):
             'model_description': model_description,
             'record': self,
             'record_name': record_name,
-            'subtitle': False,
+            'subtitles': [record_name],
             # user / environment
             'company': company,
             'email_add_signature': email_add_signature,
@@ -3070,7 +3073,7 @@ class MailThread(models.AbstractModel):
                 body=assignation_msg,
                 partner_ids=partner_ids,
                 record_name=record.display_name,
-                email_layout_xmlid='mail.mail_notification_light',
+                email_layout_xmlid='mail.mail_notification_layout',
                 model_description=model_description,
             )
 
diff --git a/addons/project/data/mail_template_data.xml b/addons/project/data/mail_template_data.xml
index e524ff084b6..8a23374840a 100644
--- a/addons/project/data/mail_template_data.xml
+++ b/addons/project/data/mail_template_data.xml
@@ -100,15 +100,12 @@
 
         <!-- You have been assigned email -->
         <template id="project_message_user_assigned">
-<p style="margin: 0px;">
-    <span>Dear <t t-esc="assignee_name"/>,</span><br />
+<div style="margin: 0px; padding: 0px; font-size: 13px;">
+    <span>Dear <t t-esc="assignee_name"/>,</span>
+    <br/><br/>
     <span style="margin-top: 8px;">You have been assigned to the <t t-esc="model_description or 'document'"/> <t t-esc="object.display_name"/>.</span>
-</p>
-<p style="padding-top: 24px; padding-bottom: 16px;">
-    <a t-att-href="access_link" t-att-data-oe-model="object._name" t-att-data-oe-id="object.id" style="background-color:#875A7B; padding: 10px; text-decoration: none; color: #fff; border-radius: 5px;">
-            View <t t-esc="model_description or 'document'"/>
-    </a>
-</p>
+    <br/>
+</div>
         </template>
     </data>
 </odoo>
diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index 6f1ebf48d57..391ae1bf7c4 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -2045,8 +2045,6 @@ class Task(models.Model):
 
         result = super(Task, tasks).write(vals)
 
-        self._task_message_auto_subscribe_notify({task: task.user_ids - old_user_ids[task] - self.env.user for task in self})
-
         if 'user_ids' in vals:
             tasks._populate_missing_personal_stages()
 
@@ -2065,6 +2063,8 @@ class Task(models.Model):
             if task.display_project_id != task.project_id and not task.parent_id:
                 # We must make the display_project_id follow the project_id if no parent_id set
                 task.display_project_id = task.project_id
+
+        self._task_message_auto_subscribe_notify({task: task.user_ids - old_user_ids[task] - self.env.user for task in self})
         return result
 
     def update_date_end(self, stage_id):
@@ -2141,6 +2141,20 @@ class Task(models.Model):
     # Mail gateway
     # ---------------------------------------------------
 
+    def _notify_by_email_prepare_rendering_context(self, message, msg_vals=False, model_description=False,
+                                                   force_email_company=False, force_email_lang=False):
+        render_context = super()._notify_by_email_prepare_rendering_context(
+            message, msg_vals, model_description=model_description,
+            force_email_company=force_email_company, force_email_lang=force_email_lang
+        )
+        if self.date_deadline:
+            render_context['subtitles'].append(
+                _('Deadline: %s', self.date_deadline.strftime(get_lang(self.env).date_format)))
+        elif self.date_assign:
+            render_context['subtitles'].append(
+                _('Assigned On: %s', self.date_assign.strftime(get_lang(self.env).date_format)))
+        return render_context
+
     @api.model
     def _task_message_auto_subscribe_notify(self, users_per_task):
         # Utility method to send assignation notification upon writing/creation.
@@ -2165,7 +2179,7 @@ class Task(models.Model):
                     body=assignation_msg,
                     partner_ids=user.partner_id.ids,
                     record_name=task.display_name,
-                    email_layout_xmlid='mail.mail_notification_light',
+                    email_layout_xmlid='mail.mail_notification_layout',
                     model_description=task_model_description,
                 )
 
diff --git a/addons/purchase/models/purchase.py b/addons/purchase/models/purchase.py
index 199716d2cfb..b6781b4b8c4 100644
--- a/addons/purchase/models/purchase.py
+++ b/addons/purchase/models/purchase.py
@@ -366,15 +366,17 @@ class PurchaseOrder(models.Model):
             message, msg_vals, model_description=model_description,
             force_email_company=force_email_company, force_email_lang=force_email_lang
         )
+        subtitles = [render_context['record'].name]
         # don't show price on RFQ mail
         if self.state not in ['draft', 'sent']:
             if self.date_order:
-                render_context['subtitle'] = _('%(amount)s due\N{NO-BREAK SPACE}%(date)s',
-                            amount=format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')),
-                            date=format_date(self.env, self.date_order, date_format='short', lang_code=render_context.get('lang'))
-                            )
+                subtitles.append(_('%(amount)s due\N{NO-BREAK SPACE}%(date)s',
+                                   amount=format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')),
+                                   date=format_date(self.env, self.date_order, date_format='short', lang_code=render_context.get('lang'))
+                                   ))
             else:
-                render_context['subtitle'] = format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang'))
+                subtitles.append(format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')))
+        render_context['subtitles'] = subtitles
         return render_context
 
     def _track_subtype(self, init_values):
diff --git a/addons/sale/models/sale_order.py b/addons/sale/models/sale_order.py
index 5189ac2d572..1991aceafa1 100644
--- a/addons/sale/models/sale_order.py
+++ b/addons/sale/models/sale_order.py
@@ -1231,15 +1231,15 @@ class SaleOrder(models.Model):
             message, msg_vals, model_description=model_description,
             force_email_company=force_email_company, force_email_lang=force_email_lang
         )
+        subtitles = [render_context['record'].name]
         if self.validity_date:
-            render_context['subtitle'] = _(
-                u'%(amount)s due\N{NO-BREAK SPACE}%(date)s',
-                amount=format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')),
-                date=format_date(self.env, self.validity_date, date_format='short', lang_code=render_context.get('lang'))
-            )
+            subtitles.append(_(u'%(amount)s due\N{NO-BREAK SPACE}%(date)s',
+                           amount=format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')),
+                           date=format_date(self.env, self.validity_date, date_format='short', lang_code=render_context.get('lang'))
+                          ))
         else:
-            render_context['subtitle'] = format_amount(
-                self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang'))
+            subtitles.append(format_amount(self.env, self.amount_total, self.currency_id, lang_code=render_context.get('lang')))
+        render_context['subtitles'] = subtitles
         return render_context
 
     def _sms_get_number_fields(self):
diff --git a/addons/test_mail/tests/test_mail_activity.py b/addons/test_mail/tests/test_mail_activity.py
index a80d0592cc5..29ac717601f 100644
--- a/addons/test_mail/tests/test_mail_activity.py
+++ b/addons/test_mail/tests/test_mail_activity.py
@@ -176,7 +176,7 @@ class TestActivityFlow(TestActivityCommon):
         rec = self.test_record.with_user(self.user_employee)
         with self.assertSinglePostNotifications(
                 [{'partner': self.partner_admin, 'type': 'email'}],
-                message_info={'content': 'assigned you an activity', 'subtype': 'mail.mt_note', 'message_type': 'user_notification'}):
+                message_info={'content': 'assigned you the following activity', 'subtype': 'mail.mt_note', 'message_type': 'user_notification'}):
             activity = rec.activity_schedule(
                 'test_mail.mail_act_test_todo',
                 user_id=self.user_admin.id)