diff --git a/addons/mail/models/mail_thread.py b/addons/mail/models/mail_thread.py
index 37dffb764ea..820f9a25cd0 100644
--- a/addons/mail/models/mail_thread.py
+++ b/addons/mail/models/mail_thread.py
@@ -2480,7 +2480,7 @@ class MailThread(models.AbstractModel):
             (
                 'user',
                 lambda pdata: pdata['type'] == 'user',
-                {}
+                {'has_button_access': True}
             ), (
                 'portal',
                 lambda pdata: pdata['type'] == 'portal',
diff --git a/addons/portal/models/portal_mixin.py b/addons/portal/models/portal_mixin.py
index bbd9576c094..be4f9e762cb 100644
--- a/addons/portal/models/portal_mixin.py
+++ b/addons/portal/models/portal_mixin.py
@@ -73,7 +73,7 @@ class PortalMixin(models.AbstractModel):
 
             new_group = [
                 ('portal_customer', lambda pdata: pdata['id'] == customer.id, {
-                    'has_button_access': False,
+                    'has_button_access': True,
                     'button_access': {
                         'url': access_link,
                     },
diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index 1d14da9bc35..42bf5d445c2 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -1975,7 +1975,7 @@ class Task(models.Model):
                 {}
             ))
         portal_privacy = self.project_id.privacy_visibility == 'portal'
-        for group_name, group_method, group_data in groups:
+        for group_name, _group_method, group_data in groups:
             if group_name in ('customer', 'user') or group_name == 'portal_customer' and not portal_privacy:
                 group_data['has_button_access'] = False
             elif group_name == 'portal_customer' and portal_privacy:
diff --git a/addons/sale/models/sale_order.py b/addons/sale/models/sale_order.py
index 168a09deb9f..3fda7ef1349 100644
--- a/addons/sale/models/sale_order.py
+++ b/addons/sale/models/sale_order.py
@@ -1069,20 +1069,6 @@ class SaleOrder(models.Model):
         transaction = self.get_portal_last_transaction()
         return (self.state == 'sent' or (self.state == 'draft' and include_draft)) and not self.is_expired and self.require_payment and transaction.state != 'done' and self.amount_total
 
-    def _notify_get_groups(self, msg_vals=None):
-        """ Give access button to users and portal customer as portal is integrated
-        in sale. Customer and portal group have probably no right to see
-        the document so they don't have the access button. """
-        groups = super(SaleOrder, self)._notify_get_groups(msg_vals=msg_vals)
-
-        self.ensure_one()
-        if self.state not in ('draft', 'cancel'):
-            for group_name, group_method, group_data in groups:
-                if group_name not in ('customer', 'portal'):
-                    group_data['has_button_access'] = True
-
-        return groups
-
     def preview_sale_order(self):
         self.ensure_one()
         return {