diff --git a/addons/mail/models/mail_thread.py b/addons/mail/models/mail_thread.py
index 83f708ba492..5e333cc56fb 100644
--- a/addons/mail/models/mail_thread.py
+++ b/addons/mail/models/mail_thread.py
@@ -2063,6 +2063,7 @@ class MailThread(models.AbstractModel):
         """ Hook to add custom behavior after having posted the message. Both
         message and computed value are given, to try to lessen query count by
         using already-computed values instead of having to rebrowse things. """
+        return
 
     def _message_mail_after_hook(self, mails):
         """ Hook to add custom behavior after having sent an mass mailing.
diff --git a/addons/mail/models/mail_thread_main_attachment.py b/addons/mail/models/mail_thread_main_attachment.py
index 82ab9b7306f..cb1bb678f3b 100644
--- a/addons/mail/models/mail_thread_main_attachment.py
+++ b/addons/mail/models/mail_thread_main_attachment.py
@@ -16,7 +16,7 @@ class MailMainAttachmentMixin(models.AbstractModel):
     def _message_post_after_hook(self, message, msg_values):
         """ Set main attachment field if necessary """
         super()._message_post_after_hook(message, msg_values)
-        self._message_set_main_attachment_id([
+        self.sudo()._message_set_main_attachment_id([
             attachment_command[1]
             for attachment_command in (msg_values['attachment_ids'] or [])
         ])
@@ -24,7 +24,7 @@ class MailMainAttachmentMixin(models.AbstractModel):
     def _message_set_main_attachment_id(self, attachment_ids):
         if attachment_ids and not self.message_main_attachment_id:
             # Assign one of the attachments as the main according to the following priority: pdf, image, other types.
-            self.sudo().with_context(tracking_disable=True).message_main_attachment_id = max(
+            self.with_context(tracking_disable=True).message_main_attachment_id = max(
                 self.env['ir.attachment'].browse(attachment_ids),
                 key=lambda r: (r.mimetype.endswith('pdf'), r.mimetype.startswith('image'))
             ).id