diff --git a/addons/mass_mailing/models/mailing.py b/addons/mass_mailing/models/mailing.py
index 06483415ab4..5715129952c 100644
--- a/addons/mass_mailing/models/mailing.py
+++ b/addons/mass_mailing/models/mailing.py
@@ -293,13 +293,15 @@ class MassMailing(models.Model):
     # ORM
     # ------------------------------------------------------
 
-    @api.model
-    def create(self, values):
-        if values.get('subject') and not values.get('name'):
-            values['name'] = "%s %s" % (values['subject'], datetime.strftime(fields.datetime.now(), tools.DEFAULT_SERVER_DATETIME_FORMAT))
-        if values.get('body_html'):
-            values['body_html'] = self._convert_inline_images_to_urls(values['body_html'])
-        return super(MassMailing, self).create(values)
+    @api.model_create_multi
+    def create(self, vals_list):
+        now = fields.Datetime.now()
+        for values in vals_list:
+            if values.get('subject') and not values.get('name'):
+                values['name'] = "%s %s" % (values['subject'], now)
+            if values.get('body_html'):
+                values['body_html'] = self._convert_inline_images_to_urls(values['body_html'])
+        return super().create(vals_list)
 
     def write(self, values):
         if values.get('body_html'):
diff --git a/addons/mass_mailing/models/mailing_contact.py b/addons/mass_mailing/models/mailing_contact.py
index 6ebd1132820..16a13125359 100644
--- a/addons/mass_mailing/models/mailing_contact.py
+++ b/addons/mass_mailing/models/mailing_contact.py
@@ -27,15 +27,17 @@ class MassMailingContactListRel(models.Model):
          'A contact cannot be subscribed multiple times to the same list!')
     ]
 
-    @api.model
-    def create(self, vals):
-        if 'opt_out' in vals:
-            vals['unsubscription_date'] = vals['opt_out'] and fields.Datetime.now()
-        return super(MassMailingContactListRel, self).create(vals)
+    @api.model_create_multi
+    def create(self, vals_list):
+        now = fields.Datetime.now()
+        for vals in vals_list:
+            if 'opt_out' in vals:
+                vals['unsubscription_date'] = now if vals['opt_out'] else False
+        return super().create(vals_list)
 
     def write(self, vals):
         if 'opt_out' in vals:
-            vals['unsubscription_date'] = vals['opt_out'] and fields.Datetime.now()
+            vals['unsubscription_date'] = fields.Datetime.now() if vals['opt_out'] else False
         return super(MassMailingContactListRel, self).write(vals)