I used this method in the past http://www.msexchange.org/tutorials/MF009.html
The nice thing is since you are using groups, you can easily add and remove people from the group. From: Evan Brastow [mailto:[EMAIL PROTECTED] Sent: Tuesday, September 09, 2008 1:37 PM To: MS-Exchange Admin Issues Subject: Stopping an email user from sending to anyone outside of the organization? Hi, I'm wondering if someone could point me to a way to allow a user to send email within the company, but not to any external addresses? We only have one domain and one server (Exchange 2003 Enterprise), so it shouldn't be too complicated, I would think. Thank you, Evan ~ Ninja Email Security with Cloudmark Spam Engine Gets Image Spam ~ ~ http://www.sunbeltsoftware.com/Ninja ~