Question : Exchange Problems

we have a in house exchange server 2003  for staff we also have an external mail service  handled by a third party. we use the external mail server to handle clients. we have our clients as cnotacts in our internal exhange server, which was working find until we decided to change domain names now we can not send email to our external exchange server from our internal exchange server. we can sucessfully sent from outside personal email to our external server but not from inside. ir must be some kind of DNS issue but i try cleating cashe  which doesn't seem to fix the problem. please help

Answer : Exchange Problems

What are the email domains in use? If you have recipients using the same email domain on both Exchange Servers, you need to share the SMTP namespace: http://www.msexchange.org/tutorials/Exchange-2003-SMTP-Namespace-Sharing.html.

-Matt