I am trying to send mail to myself, from what I can see it is 2003 domain with Exchange 2010 co existing with 2003.
I have created myself as a user with a mailbox I can log in via webmail I can send out but when someone tries to send me a mail they get the following error
The recipient's e-mail address was not found in the recipient's e-mail system. Microsoft Exchange will not try to redeliver this message for you. Please check the e-mail address and try resending this message, or provide the following diagnostic text to your system administrator.