diff --git a/addons/mail/models/ir_actions.py b/addons/mail/models/ir_actions.py
index 870f11a5b40..ef9495f52fd 100644
--- a/addons/mail/models/ir_actions.py
+++ b/addons/mail/models/ir_actions.py
@@ -65,7 +65,7 @@ class ServerActions(models.Model):
     @api.constrains('state', 'model_id')
     def _check_activity_mixin(self):
         for action in self:
-            if action.state == 'next_activity' and not issubclass(self.pool[action.model_id.model], self.pool['mail.thread']):
+            if action.state == 'next_activity' and not action.model_id.is_mail_thread:
                 raise ValidationError(_("A next activity can only be planned on models that use the chatter"))
 
     @api.model
diff --git a/addons/mail/views/ir_model_views.xml b/addons/mail/views/ir_model_views.xml
index ba1f89299e4..f146375f266 100644
--- a/addons/mail/views/ir_model_views.xml
+++ b/addons/mail/views/ir_model_views.xml
@@ -8,6 +8,7 @@
             <field name="transient" position="after">
                 <field name="is_mail_thread" attrs="{'readonly': [('state','!=', 'manual')]}" groups="base.group_no_one"/>
                 <field name="is_mail_activity" attrs="{'readonly': [('state','!=', 'manual')]}" groups="base.group_no_one"/>
+                <field name="is_mail_blacklist" attrs="{'readonly': [('state','!=', 'manual')]}" groups="base.group_no_one"/>
             </field>
             <xpath expr="//field[@name='field_id']//field[@name='copied']" position="after">
                 <field name="tracking" attrs="{'readonly': [('state','!=', 'manual')]}"/>
@@ -22,6 +23,7 @@
             <field name="model" position="after">
                 <filter string="Mail Thread" name="is_mail_thread" domain="[('is_mail_thread', '=', True)]"/>
                 <filter string="Mail Activity" name="is_mail_activity" domain="[('is_mail_activity', '=', True)]"/>
+                <filter string="Mail Blacklist" name="is_mail_blacklist" domain="[('is_mail_blacklist', '=', True)]"/>
             </field>
         </field>
     </record>