diff --git a/addons/mail/models/ir_attachment.py b/addons/mail/models/ir_attachment.py
index acc14b2b6f9..4330059c495 100644
--- a/addons/mail/models/ir_attachment.py
+++ b/addons/mail/models/ir_attachment.py
@@ -23,5 +23,5 @@ class IrAttachment(models.Model):
         related_record = self.env[self.res_model].browse(self.res_id)
         # message_main_attachment_id field can be empty, that's why we compare to False;
         # we are just checking that it exists on the model before writing it
-        if hasattr(related_record, 'message_main_attachment_id'):
+        if related_record and hasattr(related_record, 'message_main_attachment_id'):
             related_record.message_main_attachment_id = self