I am getting the following error while trying to send an email to some with an @alonso.tv email address.
5.5.0 smtp;551 User not local. Authentication required for relay
I am using Exchange 2003 and I have no issues sending to other external accounts. I also did a mail trace and I get the error exactly when it tries to leave the server.
I am not sure what is going on
Thank you for all of your help in advance