I have a list of 50,000 emails. Some of them are non-existent.
When we send email to that list, some emails are not being delivered (given that some recipients are non-existing), so we get an email like this:
Mail Delivery System <MAILER-DAEMON@[url removed, login to view]> I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below....
We need to attach these notification emails to a php script to flag these emails in the database so we don't use them in future time.