What is backscatter ?
Email failure or Automatic Reply emails sent to an email address, in reply to SPAM or bogus email sent using your email address.
If your email address is posted on a web page you are very likely to get 100ís or 1,000ís of failed delivery, out-of-office messages, backscatter.
If the option to turn on backscatter filters exist and you enable them, you will not get genuine mail delivery failures. However if you are getting loads and loads of backscatter emails this is a small price to pay for being inundated with many useless backscatter emails.
These filters are mainly used by business email servers, to reduce network and mail server usage to save money and time.
The easiest way to ignore these and send direct to your deleted folder is to create a rule to find "Authentication Required" in the email body and move the email to the "deleted items" folder.