NDR – Sorry the email could not be delivered

Q:  I receive an NDR that says "Sorry the email could not be delivered. The user name@domain.com does not exist or is not authorized to use this forwarder."

A:  This error typically is caused by a user who is not enabled on a Forwarder. Edit the forwarder and confirm the user is selected. This error can also be caused if there is a name in the CC field of your email. However using BCC does not cause a problem. If you need to copy someone on an email sent to ErC - please use the BCC field.