Add Content-ID header in attachment.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@24191 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Tool/NotificationTool.py

@@ -166,6 +166,8 @@ def buildEmailMessage(from_url, to_url, msg=None,
 
     part.add_header('Content-Disposition',
                     'attachment; filename=%s' % attachment_name)
+    part.add_header('Content-ID',
+                    '%s' % attachment_name)
     message.attach(part)
 
   return message