Use the information in the NDR to help you decide how to fix the problem. Why did I get this bounce message?įor more information, see the Causes for error code 4.4.7 section later in this article. This article describes what you can do if you see error code 550 4.4.7 in a non-delivery report (also known as an NDR, bounce message, delivery status notification, or DSN). It's frustrating when you get an error after sending an email message. Mail flow rules are now available in the new Exchange admin center.
